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  • 1985-1989  (787)
  • 1940-1944
  • 1870-1879
  • 1840-1849
  • 1985  (787)
  • Organic Chemistry  (671)
  • Life Sciences
  • breast cancer
Material
Years
  • 1985-1989  (787)
  • 1940-1944
  • 1870-1879
  • 1840-1849
Year
  • 1
    ISSN: 1436-2813
    Keywords: breast cancer ; tritiated thymidine ; estrogen receptors ; progesterone receptors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We carried out studiesto determine whether the Tritiated Thymidine Labeling Index (TLI) would correlate with hormone receptors as well as with clinical and histological data. Sixty-four patients with breast cancer were the subjects studied. TLI showed no relationship to age, menopausal status, T-factor, n-factor, stage, or histological type. However, compared to tubule formation, nuclear pleomorphism, and mitotic activity, TLI showed a positive correlation with each and accordingly there was a positive correlation between TLI and Bloom’s histological grading. The cumulative disease-free rate at three years was higher in case of a TLI below 4.0 (median TLI value). TLI significantly correlated inversely with the binding sites not only of cytoplasmic estrogen receptors (ERC), but also of cytoplasmic progesterone receptors (PRC) and nuclear estrogen receptors (ERN). Cancers negative for all three receptors indicated the highest TLI, while cancers positive for all three receptors showed the lowest TLI. The results suggest that breast cancers positive for hormone receptors were of low malignancy because lower TLI related to a lower proliferative activity. Thus, TLI is an useful parameter for assessing the clinical status of breast cancers.
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  • 2
    ISSN: 1436-2813
    Keywords: estrogen receptor ; breast cancer ; immunoperoxidase technique
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The estrogen receptors (ER) in breast cancer tissues were investigated in 122 patients using an immunoperoxidase method. ER (+) were evident in 77 of 122 patients (63.1 per cent). If classified according to pre-and postmenopausal subjects. ER (+) was seen in 61.4 per cent and ER (−) in 32.9 per cent before menopause, and ER (+) in 65.4 per cent and ER (−) in 30.8 per cent after menopause with no marked difference between the two. If classified according to histological type, ER (+) was seen in 73.2 per cent of those with papillotubular carcinoma and in 62.0 per cent of those with scirrhous carcinoma, whereas ER (−) was seen in 44.9 per cent of those with medullary tubular carcinoma. ER (+) was seen in carcinoma with apocrine metaplasia, lobular carcinoma and Paget's carcinoma. Concerning the relationship between primary tumors and metastatic lymph nodes, ER (+) for both was seen in 20 of 41 patients (48.8 per cent) whereas ER (−) for both was found in 9 of 41 patients (22.0 per cent). Four patients with local recurrences had a positive ER (+) at the beginning of treatment, but the ER became negative after hormonal treatment and chemotherapy.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Surgery today 15 (1985), S. 420-426 
    ISSN: 1436-2813
    Keywords: breast cancer ; mastectomy ; adjuvant chemotherapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Since the 1950's the treatment of breast cancer has changed substantially. This related surgery has become less disfiguring without either impairing survival or increasing recurrences. Adjuvant chemotherapy has also contributed.
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  • 4
    ISSN: 1436-2813
    Keywords: aspiration biopsy cytology ; breast cancer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract From November 1981 to the end of August 1984, 456 patients with breast lesions underwent aspiration biopsy cytology (A.B.C.). This study includes 109 for whom the diagnosis was histologically confirmed at surgical biopsy. Seventy-five lesions were histologically proven to be malignant and 34 were benign. The accuracy of diagnoses with A.B.C. was; true positive 86.7 per cent (65/75) of the time, true negative 82.6 per cent (28/34) of the time, false negative 5.3 per cent (4/75) of the time and false positive 5.7 per cent (2/34) of the time. Unsatisfactory or inadequate aspirated tissue made A.B.C. diagnosis difficult in 5.5 per cent (6/109) of the cases. Three out of 7 with malignant tumors, who were wrongly diagnosed as benign by A.B.C., had tumors with a diameter of 1.0 cm or less. Two benign cases which were falsely diagnosed as malignant also had small tumors about 1.0 cm in diameter. Although A.B.C. is more reliable than other conventional supplementary diagnostic techniques (mammography, ultrasonography, etc.), it is important to carefully follow clinically questionable cases which appear negative, using A.B.C.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Investigational new drugs 3 (1985), S. 133-137 
    ISSN: 1573-0646
    Keywords: breast cancer ; mitoxantrone ; response ; toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Forty-two women with measurable or evaluable advanced breast cancer who had received neither prior chemotherapy for advanced disease nor any anthracycline-containing regimen as adjuvant were entered in a phase II study of mitoxantrone (Novantrone®; dihydroxyanthracenedione). Patients were aged from 36 to 80 years, performance status was from 0 to 2. All patients had normal hematological status and normal renal and liver function tests. Cardiac scintigraphy and sonography techniques were used to monitor cardiac function. Mitoxantrone was administered at a dose of 14 mg/m2 in 100 ml 5% dextrose solution over 30 minutes, repeated every three weeks. The number of courses per patient ranged from 2 to 12. Of 42 eligible patients 39 were fully evaluable for response and all for drug toxicity. Responses to treatment were: complete response four patients, partial response 10 patients, stable disease 18 patients and progressive disease seven patients. The overall response rate was 36% (95% confidence limits 20–52%). Three patients showed decreased left ventricular ejection fraction but no patient developed signs of overt left ventricular failure during the treatment period. Hematological and gastrointestinal toxicities were mild. Hair loss was minimal. The data indicate that mitoxantrone is an effective agent for the treatment of advanced breast cancer with mild side-effects, especially with respect to nausea/vomiting, hair loss and cardiotoxicity.
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  • 6
    ISSN: 1573-0646
    Keywords: mitoxantrone ; combination chemotherapy ; breast cancer ; fluorouracil ; vincristine ; cyclophosphamide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In our wide experience of treating advanced breast carcinoma with chemotherapy, the combination of doxorubicin (DOX), vincristine (VCR), cyclophosphamide (CPM) and fluorouracil (FU) gave a complete plus partial response rate of over 60%, with 100% alopecia and frequent cardiac toxicity depending on total dose. After the EORTC Clinical Screening Group phase II trial we have conducted an “expected difference method” comparative phase II trial using the combination DOX, VCR, CPM, FU and the combination of MTX (10mg/m2), VCR, CPM and FU on a population of 50 breast carcinoma patients similar to those taking part in the first study. The reasons for similarity of action will be presented and discussed.
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  • 7
    ISSN: 1573-0646
    Keywords: vincristine ; mitomycin-C ; mitoxantrone ; toxicity ; breast cancer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Nineteen patients with advanced, previously treated breast cancer received treatment with vincristine 2 mg i.v., mitomycin-C 6 mg/m2 and mitoxantrone (Novantrone®; dihydroxyanthracenedione) 12 mg/m2 i.v. every three weeks. Thirteen patients are evaluable for response and toxicity. Partial remission was seen in six patients, with soft tissue, bone and visceral metastases and static disease in a further four patients. Median duration of response has not yet been reached (8+ months). Toxicity was mild and predictable, with no patient experiencing severe nausea and vomiting, and only four of the patients requiring a wig for alopecia. Malaise and lethargy were common in those patients receiving more than three courses, and an increase in the mean corpuscular volume (MCV) together with a fall in haemoglobin were seen in patients receiving multiple courses of treatment. The study suggests that this combination is active, and may prove useful with other agents in the treatment of breast cancer.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-7217
    Keywords: breast cancer ; intraductal carcinoma ; intraductal papilloma ; atypical structure ; 3-D reconstruction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The basic architectural pattern of intraductal proliferative lesions of the breast was established by reconstructing serial sections of luminal spaces and interluminal areas of glandular structures. The materials were surgical specimens from twenty patients with intraductal carcinoma, papilloma, papillomatosis, or so-called borderline lesion. In papilloma and papillomatosis, the luminal spaces were tubular and interconnected forming a three-dimensional (3-D) network, whereas carcinoma was a porous structure with dispersed lumina. The latter represented 3-D atypical structure in intraductal carcinoma. In borderline lesion the architecture was an intermediate type, with separate lumina partially transformed into tubular shapes. It was also confirmed that the porous structure of carcinoma observed in 3-D reconstructions corresponded to the cribriform pattern seen in 2-D figures, while the network of papilloma produced a complex glandular pattern. A geometric parameter was devised to measure the different 3-D patterns of lumina and their 2-D expressions. It was concluded that the 3-D architectural pattern of intraductal proliferations was sufficiently characteristic to be of diagnostic value in differentiating these diseases.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Breast cancer research and treatment 6 (1985), S. 137-144 
    ISSN: 1573-7217
    Keywords: breast cancer ; Pathology ; pregnancy ; rapidly progressing breast cancer ; young women
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Conflicting opinions exist concerning clinical and pathological presentation, as well as evolution and prognosis, of breast cancer in young women. The roles of associated pregnancy and lactation on these parameters is also unclear. These two conditions are studied in the present work through the comparison of two breast cancer patient age groups: patients under the age of 30 (Group A) and premenopausal patients aged 45–49 (Group B). Rapidly growing and/or inflammatory breast cancer (rapidly progressing breast cancer: RPBC) — a special form of Breast Cancer with a poor prognosis very frequent in the Tunisian breast cancer population — was more often present among Group A patients. This difference is a consequence of the more frequent association of this breast cancer group with pregnancy or lactation; nearly all the cases of breast cancer associated with pregnancy or lactation are RPBC. For breast cancer without the pregnancy/lactation association, the younger group generally shows poorer histological grading and more severe evolution. The number of patients in our study is not really sufficient to allow statistically significant conclusions, but it does seem clear that young age and associated pregnancy/lactation are aggravating factors in Tunisian breast cancer patients.
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  • 10
    ISSN: 1573-7217
    Keywords: breast cancer ; estrogen receptors ; histochemistry ; progesterone receptors ; prognostic factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Estrogen receptors (ER) were evaluated in 634 breast cancer patients by the dextran-coated charcoal method (DCC). In 206, ER and progesterone receptors (PR) were also tested by cytochemistry (Lee method), and in 124 ER were tested by immunofluorescence (Pertschuk method). The median follow-up is 3.7 years. Comparisons have been made between receptor content and:1) anatomical and clinical features, 2) disease-free survival (DFS), and 3) survival. The following conclusions can be drawn: a) there is no correlation between ER determinations by DCC and by immunofluorescence or cytochemical methods; b) there is no evidence of association between ER and PR determined by Lee's method and anatomical and clinical features; c) a highly significant positive association was found between ER rich specimens and age, post-menopausal status, lobular and tubular histologic types; d) there is no association between ER values and TNM stage, WHO grading, pathologic prognostic factors of primary tumor and of lymph nodes; and e) the DFS was not affected by ER status, except for tumors with more than 50 fmol/mg protein.
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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Breast cancer research and treatment 6 (1985), S. 229-235 
    ISSN: 1573-7217
    Keywords: tamoxifen ; medroxyprogesterone acetate ; breast cancer ; soft agar cloning assay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The human tumor soft agar cloning assay has been used to assess the biological effects of cytotoxic drugs and other agents on human cancers. In this study we have examined the effects of two hormonal agents, tamoxifen (Tam) and medroxyprogesterone acetate (MPA), on colony growth of the MCF-7 human breast cancer cell line as well as fresh human breast cancer specimens. Using standard criteria for a colony (〉50 cells or 〉60 microns in diameter) Tam (1.0µM) reduced MCF-7 colony formation by only 30% to 50%, and MPA (1.0µM) had no effect. However, both agents dramatically reduced the formation of larger colonies; less than 10% of colonies larger than 124 microns survived Tam exposure, and less than 25% survived with MPA.In vitro sensitivity (〈 30% colony survival) of fresh human breast cancer specimens was observed infrequently with either Tam (1/39 evaluable assays) or MPA (3/36 evaluable assays). Colony growth of human breast cancer was unaltered when cells were plated in charcoal-stripped serum to reduce the endogenous estrogen concentration.In vitro sensitivity to Tam or MPA was not increased under these conditions. No correlation was found between estrogen receptor (ER) concentration and inhibition of colony survival with Tam or MPA. None of 16 assays from ER-positive specimens treated with Tam and 2 of 18 ER-positive specimens treated with MPA were sensitivein vitro. In contrast, 2 of 12 ER-negative specimens tested with Tam and 3 of 7 ER-negative specimens tested with MPA were sensitivein vitro. Stimulation of colony growth was observed in about 20% of Tam or MPA-treated specimens. Of the assays with ER data available, 10 of 11 with enhanced colony growth were ER-positive. Human breast cancer specimens did not grow well enough to assess the effect of these agents on large-sized colonies. These data suggest that the standard human tumor cloning assay will need modification before it can be used to predict hormonal sensitivity of fresh human breast cancer specimens.
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  • 12
    ISSN: 1573-7217
    Keywords: histochemistry ; estrogen receptor ; monoclonal antibodies ; breast cancer ; immunocytochemistry ; fluorescent estrogen conjugates ; type II estrogen binding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Breast cancer specimens from 184 patients were analyzed for estrogen binding by two different histochemical techniques using conjugates of estradiol, bovine serum albumin, and fluorescein. In one conjugate estradiol was bound at position 6, in the other at position 17. Results were in agreement in 64% (p〈.001), but obvious differences in ligand distribution were noted. Results were also correlated with estrogen receptor (ER) analysis by dextran-coated charcoal assay (DCC) and were in accord in 65% and 67% of specimens respectively (p〈.001). In 114 cases, the tissue samples were also studied with the estrogen receptor immunocytochemical assay (ERICA) of Greene and his colleagues, which employs monoclonal antibodies to ER protein. Results were in accord with DCC in 86% (p〈.001). The pattern of staining with ERICA differed from that of either histochemical method. In 43 cases assay results were correlated with clinical endocrine response. Overall, the best statistical prognostic parameters were obtained with ERICA. Analysis of combined assay results revealed that patients with assays positive by all techniques were the most likely to respond to hormonal treatment (p〈.001), whereas if one or more assays were negative the chances for a good response were significantly less favorable. These data suggest that DCC and ERICA are both a measure of the same estrogen binding site (type I) while the histochemical methods apparently identify two other separate and distinct sites (putative type II sites). A degree of positive interaction may exist between these multiple estrogen binding sites.
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Breast cancer research and treatment 5 (1985), S. 189-194 
    ISSN: 1573-7217
    Keywords: mitomycin-C ; metronidazole ; breast cancer ; pulmonary toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Twenty-seven patients with metastatic adenocarcinoma of the breast refractory to other chemotherapy were treated with mitomycin-C plus metronidazole. The mitomycin-C dose was 15–20 mg/m2 I. V. repeated every 6–9 weeks. Metronidazole 1.5 g/m2 was given p.o. 12 hr and 1 hr before mitomycin-C and again 6 hr and 24 hr after mitomycin-C. Partial remissions were noted in 4 of 24 (17%) evaluable patients. Good performance status patients who were lightly pretreated, unresponsive to prior chemotherapy, and estrogen receptor negative were most likely to respond, and further studies are indicated in this subgroup of patients. Hematological toxicity was similar to that anticipated with mitomycin-C alone. Gastrointestinal toxicity was probably increased. Three probable and 2 possible cases of pulmonary toxicity were seen. It is unclear whether the incidence of mitomycin-C pulmonary toxicity was increased by the metronidazole.
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Breast cancer research and treatment 5 (1985), S. 221-229 
    ISSN: 1573-7217
    Keywords: breast cancer ; cancer ; chromosomes ; oncogenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Chromosomal and molecular biologic studies of human breast cancer are beginning to provide insight into the basic biology of this important disease. The current state of knowledge of both cytogenetic evaluation and assessment of expression and amplification of cellular oncogenes in breast cancer will be outlined in this brief review.
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Breast cancer research and treatment 5 (1985), S. 37-46 
    ISSN: 1573-7217
    Keywords: breast cancer ; non-histone nuclear proteins ; biological markers ; DMBA-induced rat mammary tumors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Nuclear proteins were extracted from purified nuclei of 7,12-dimethylbenz(a)anthracene (DMBA)-induced tumors and normal mammary glands of the rat by enzymatic treatment. Of the 34 bands indicated by onedimensional polyacrylamide gel electrophoresis of nuclear proteins, 6 appeared in high concentration in tumors but were found as traces or undetectable in normal glands; 6 others were clearly shown in the latter but were not detectable or greatly reduced in the former. Two-dimensional electrophoresis identified about 130 and 92 non-histone proteins in normal mammary and tumor cell nuclei respectively. Marked differences in spot density were noted especially in spots (M.W. × 10−3/pI) 100/5.7 and 200/5.5 of tumors and 28/7.1, 32/5.4, 36/5.4, 38/6.9, and 68/6.0 of normal tissue. The relationship between these nuclear proteins and the development of mammary tumors is also discussed.
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Breast cancer research and treatment 5 (1985), S. 17-21 
    ISSN: 1573-7217
    Keywords: breast cancer ; axillary treatment ; surgery ; radiation ; dissection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We have reviewed the available clinical data on the benefit of axillary treatment in patients with early breast cancer. The results of these studies suggest that perhaps 5–10% of patients are cured by effective axillary treatment. We conclude that effective axillary treatment should still be considered an essential aspect of primary treatment.
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  • 17
    Electronic Resource
    Electronic Resource
    Springer
    Breast cancer research and treatment 5 (1985), S. 67-73 
    ISSN: 1573-7217
    Keywords: androgen metabolism ; apocrine differentiation ; breast cancer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Metabolism of (7α-3H) testosterone has been measured in 111 human breast cancers and compared retrospectively with the degree of apocrine differentiation in the tumors. Cancers in which apocrine characteristics were a marked feature metabolized significantly more testosterone precursor than those in which apocrine features did not predominate. Higher metabolism was accounted for by increased conversion to 5α-reduced products such as 5α-dihydrotestosterone and 5α-androstanediols.
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  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Breast cancer research and treatment 5 (1985), S. 75-80 
    ISSN: 1573-7217
    Keywords: androgen treatment ; breast cancer ; hormone receptors ; nandrolone decanoate ; tamoxifen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Since 1980 we have been carrying out a prospective randomized trial comparing tamoxifen with the combination of tamoxifen plus nandrolone decanoate in advanced breast cancer. The tamoxifen dose is 30 mg daily and the nandrolone decanoate dose 100 mg i.m. once a week for four weeks and thereafter every other week. 98 post-menopausal patients have been evaluated for the response. The number of patients is 49 in both groups. The overall response rates (CR +PR) to tamoxifen and tamoxifen plus nandrolone decanoate were not significantly different; in the tamoxifen group the response rate was 49% and in the combination group 45%. The mean time to progression in tamoxifen group is over 13 months and in tamoxifen plus nandrolone decanoate group over 12 months. Our results do not suggest a synergistic effect from combining tamoxifen and nandrolone decanoate treatments. The response rates to tamoxifen at different sites of metastases were as follows: bones 47%, soft tissues 56%, and viscera 48%. The respective figures with the combination therapy were 36%, 64%, and 40%. Both treatments were well tolerated and in no patient was withdrawal of the therapy necessary. Mild virilization and hoarseness were experienced by all patients treated with nandrolone decanoate. Side-effects associated with tamoxifen were rare, although five patients experienced nausea and two had hot flushes.
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  • 19
    ISSN: 1573-7217
    Keywords: breast cancer ; chemotherapy ; adjuvant treatment ; CMF program
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The paper reviews all adjuvant studies carried out since 1973 at the Milan Cancer Institute in women with resectable breast cancer and positive axillary nodes. The updated results essentially confirm previous findings, and indicate that CMF-based chemotherapy is able to exert a prolonged therapeutic activity in a fraction of patients bearing micrometastases. In particular, the first randomized study testing no postoperative chemotherapy vs 12 CMF cycles, showed a 10-year relapse free survival (RFS) of 31.4% vs 43.4% (P〈0.001) and an overall survival (OS) of 47.3% vs 55.2% (P = 0.10), respectively. Findings related to subsets indicated that RFS and OS benefit was significant in premenopausal and not in postmenopausal women, and in both treatment groups the observed findings were always related to the number of histologically positive nodes. On relapse, salvage therapy administered to controls failed to produce superior results compared to those achieved in the CMF group. The 8-year results of the second study testing 12 vs 6 CMF cycles failed to show a significant difference between the two treatment groups. This indicated that the maximum tumor cell kill occurred during initial chemotherapy cycles. In the third study, carried out only in postmenopausal women ⩽65 years, sequential non-cross resistant combinations (CMFP → AV) at full dose achieved superior results compared to CMF in the subset with limited nodal extent. Acute side effects were moderate and no delayed morbidity, including increased incidence of second neoplasms, was observed. We conclude that the tumor cell heterogeneity, and in particular primary drug resistance, represents the major obstacle to adjuvant systemic therapy in high risk breast cancer. Current results suggest that 6 cycles of CMF can be considered a simple, safe, and moderately effective adjuvant therapy. Future trials should contemplate treatments of different intensity related to major prognostic subsets, while in women at very high risk of early relapse more vigorous drug regimens should be concentrated within the first six months from local-regional therapy.
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  • 20
    Electronic Resource
    Electronic Resource
    Springer
    Breast cancer research and treatment 5 (1985), S. 195-200 
    ISSN: 1573-7217
    Keywords: adjuvant chemotherapy ; breast cancer ; weight gain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Weight gain during adjuvant chemotherapy has been reported by several authors. Because increased body weight at diagnosis is associated with an increased risk of disease recurrence, we have assessed the prevalence of weight gain in a series of patients receiving adjuvant treatment, as well as the association of weight gain with type of treatment and risk of recurrence. We first assembled an inception cohort of 237 patients who had all undergone pretreatment evaluation and treatment at one institution, and had already been followed for at least 12 months. Body weight at the start and completion of treatment was recorded, as was type of treatment and status at last followup. Ninety-six percent of patients gained weight during treatment and none lost weight (mean increase 4.3 kg). Weight gain was strongly associated with treatment, and was least in patients receiving single agent chemotherapy, greatest in patients treated with ovarian ablation and prednisone, and intermediate in those receiving combination chemotherapy. There was no association between weight gain and disease recurrence.
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  • 21
    ISSN: 1573-7217
    Keywords: antiestrogens ; antiestrogen binding sites ; breast cancer ; estrogen receptors ; growth inhibition ; mechanism of antiestrogen action ; tamoxifen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Antiestrogens have proven to be effective in controlling the growth of hormone-responsive breast cancers. At the concentrations of antiestrogens achieved in the blood of breast cancer patients taking antiestrogens (up to 2 × 10−6 M), antiestrogens selectively inhibit the proliferation of estrogen receptor-containing breast cancer cells, and this inhibition is reversible by estradiol. Antiestrogens also inhibit estrogen-stimulation of several specific protein synthetic activities in breast cancer cells, including increases in plasminogen activator activity, progesterone receptor levels and production of several secreted glycoproteins and intracellular proteins. Antiestrogens bind with high affinity to the estrogen receptor and to additional microsomal binding sites to which estrogens do not bind. These latter sites, called antiestrogen binding sites (AEBS), are present in equal concentrations in estrogen receptor-positive and -negative breast cancer cells and are present in a wide variety of tissues, with highest concentrations being found in the liver. The antiestrogenic and growth suppressive potencies of a variety of antiestrogens correlate best with their affinity for estrogen receptor and not with affinity for AEBS. Antiestrogens undergo bioactivation and metabolismin vivo and hydroxylated forms of the antiestrogen have markedly enhanced affinities for the estrogen receptor. Detailed studies with high affinity radiolabelled antiestrogens indicate that antiestrogens induce important conformational changes in receptor that are reflected in the enhanced maintenance of a 5 S form of the estrogen receptor complex; reduced interaction with DNA; and altered activation and dissociation kinetics of the antiestrogen-estrogen receptor complex. These conformational changes effected by antiestrogens likely result in different interactions with chromatin, causing altered cell proliferation and protein synthesis. Analyses of the rates of synthesis and turnover of the estrogen receptor through pulse-chase experiments utilizing the covalently attaching antiestrogen, tamoxifen aziridine, and studies employing dense amino acid labeling of estrogen receptor reveal that the antiestrogen-occupied receptor is degraded at a rate (t 1/2 = 4 h) similar to that of the control unoccupied receptor. Hence, antiestrogens do not prevent estrogen receptor synthesis and they do not either accelerate or block estrogen receptor degradation. Our findings raise serious doubts about the role of the AEBS in mediating directly the growth suppressive actions of antiestrogens, and suggest that interaction with the estrogen receptor is most likely the mechanism underlying the growth-inhibitory effects of antiestrogens. At present, the role of the AEBS in the actions of antiestrogens or in possible antiestrogen metabolism remains unclear.
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  • 22
    ISSN: 1573-7217
    Keywords: breast cancer ; histoprognosis ; interobserver ; nuclear grade ; reproducibility ; surgical pathology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Eleven surgical pathologists studied microscopic sections from 45 mastectomy specimens of node positive breast cancer patients who had been entered into ECOG clinical trials. Inter-observer reproducibility for histoprognostic features was examined as a prerequisite before a subsequent evaluation of their possible clinical applicability could be undertaken. Histological type, nuclear grade, tubular formation, and lymphoid reactions were studied in the cancerous tissues. Lymph nodal responses (follicular and pulp prominence, sinus histiocytosis) were also examined in a manner that simulated slide review in routine surgical pathology practice. Numerous two-way comparisons of the pathologists' findings resulted in low levels of agreement (usually ≪90%). The degree of inter-observer reliability is clinically unacceptable using customary slide review analysis. New ways of examining breast cancer tissues need to be explored in the search for prognostic features which can be applied to the clinical management of breast cancer patients.
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  • 23
    ISSN: 1573-7217
    Keywords: breast cancer ; cytosol ; estrogen receptor ; nucleus ; progesterone receptor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Estrogen and progesterone receptor concentrations in cytosol and nucleus were measured in 21 primary breast cancer tumors. Twelve out of the 21 tumor samples were cytosol estrogen receptor positive, 8 of which contained only unoccupied estrogen binding sites in the cytosol, but 2 of the 9 ‘estrogen receptor negative’ samples did contain cytosol binding sites already occupied by endogenous homone. Four other ‘estrogen receptor negative’ tumors only showed nuclear binding sites. Only 3 of the 12 ‘estrogen receptor positive’ tumors also contained progesterone receptors. All of these tumors also had estrogen receptor in the nucleus. However, three of the 17 ‘progesterone receptor negative’ samples had progesterone receptor only in the nucleus. The present data indicate that 3 possible classes of ‘false negative’ tumors can be encountered: 1) estrogen receptors occupied by endogenous hormone, 2) tumors containing only nuclear estrogen receptors, and 3) tumors having only nuclear progesterone receptors. Measurement of nuclear estrogen receptor together with the progesterone receptor provides further information on whether the estrogen receptor system is not only present but also functional, and should be of value in the prediction of hormone dependent breast cancer.
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  • 24
    Electronic Resource
    Electronic Resource
    Springer
    Breast cancer research and treatment 5 (1985), S. 201-205 
    ISSN: 1573-7217
    Keywords: breast cancer ; bilateral disease ; family history
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The prevalence of a family history of breast cancer was established in 54 women with bilateral primary breast cancer and 208 women with unilateral disease. Women with bilateral disease had significantly greater prevalence of family history than women with unilateral breast cancer (P〈0.01). Compared with the unilateral cancers, a significantly greater proportion of bilateral cancers had first degree affected relatives (P〈0.05). Moreover the affected relatives of probands with bilateral disease showed a significantly higher prevalence of bilateral breast cancer compared with the relatives of women with unilateral disease (P = 0.04). The findings suggested that bilateral disease was a characteristic of familial breast cancer.
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  • 25
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    Springer
    Breast cancer research and treatment 5 (1985), S. 277-283 
    ISSN: 1573-7217
    Keywords: breast cancer ; cell culture ; estrogen sensitivity ; lectin binding ; peanut agglutinin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Two estrogen-sensitive (ZR 75.1 and 734 B) and two estrogen-independent (BT 20 and Hs 578 T) human breast cancer cell lines, and one larynx carcinoma cell line (Hep. 2), were investigated immunocytochemically for the occurrence of lectin binding sites. Peroxidase-labeled peanut agglutinin (PNA) was used. PNA binding sites could be observed in estrogen-sensitive cell lines only. In ZR 75.1, the most estrogen-sensitive cell line, PNA binding sites were also observed without neuraminidase pretreatment. In our study, PNA binding is associated with the biological estrogen dependence of the tumor cells.
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  • 26
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    Springer
    Breast cancer research and treatment 5 (1985), S. 285-291 
    ISSN: 1573-7217
    Keywords: breast cancer ; mast cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The total number of mast cells and the number of such cells observed within and at the periphery of invasive breast cancers from 424 patients enrolled in protocol 4 of the National Surgical Adjuvant Breast Project were correlated with 38 other pathologic and 6 clinical features. High total mast cell counts as well as those within and at the periphery of the cancers were found to be significantly (p≤.05) associated with a patient age less than 50 years and the degree of tumor lymphoid cell reaction. The latter has also been found to be related to young age and other pathologic characteristics related to mast cell content. This suggests that the mast cells may simply represent another cell type of this reactive change. No differences in 10 year disease-free survival were detected in patients without mast cells and those exhibiting varying numbers of such cells. This information indicates that identifiable mast cells do not represent a prognostic pathologic discriminant in patients with breast cancer. However, this does not unequivocally exclude a role of mast cell secretory products, since only intact and not degranulated or disrupted forms of these cells can be counted.
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  • 27
    ISSN: 1573-7217
    Keywords: breast cancer ; monoclonal antibody ; tumor-associated antigen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Variability of tumor-associated antigens among and within human tumor cell groups presents a potential problem in the development and optimization of immunodiagnostic and therapeutic procedures for cancer. We determined the degree of expression of a tumor-associated antigen in the primary and metastatic lesions of 23 patients with infiltrating ductal carcinoma; this was accomplished using monoclonal antibody B72.3, an IgG1 generated against membrane-enriched fractions of human metastatic breast carcinomas and reactive with a 220,000–400,000 d glycoprotein complex, termed TAG-72, and the avidin-biotin complex immunoperoxidase method on fixed tissue sections. Sixteen of the 23 breast carcinomas (70%) demonstrated MAb B72.3 reactivity (range 5% to 100% of tumor cells staining). Reactivity of lymph node metastases was present in 14 of 21 patients (67%). MAb reactivity in metastases to distant sites, including bone, adrenals, liver, skin and effusions, was present in 10 of 18 patients (56%). In one patient, neither the primary carcinoma nor the metastasis to the lymph node demonstrated reactivity. There was a statistically significant positive correlation between MAb B72.3 reactivity in both primary and lymph node metastases (Kendall's Correlation Coefficient = 0.60, p = 0.0006) and between lymph node and distant metastases (Kendall's Correlation Coefficient = 0.48, p = 0.02) of the same patient. No correlation existed between antibody reactivity seen in the primary and that found in the distant lesions of that patient. These studies thus demonstrate that monoclonal antibody B72.3 can detect expression of a tumor-associated antigen in both primary and metastatic infiltrating ductal carcinoma lesions, and may prove valuable in the understanding of tumor biology of metastases and as a means for diagnosing occult disease.
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  • 28
    ISSN: 1573-7217
    Keywords: breast cancer ; disease-free interval ; estrogen receptor ; prognostic factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Specific estrogen receptor activity (ER) was found in 115 of 175 (66%) tumors of patients treated for primary breast cancer in the period 1974–1981; 60 patients had ER-negative tumors. All patients were under observation for at least 48 months (median 76 months). The 24 patients who received adjuvant chemotherapy as part of their initial treatment, were excluded from the analysis of the disease-free interval (DFI). Groups of patients with ER-positive or ER-negative tumors did not differ significantly in clinical characteristics. Patients with ER-positive tumors had a significantly longer DFI than those with ER-negative tumors only in the first year after initial treatment. After prolonged observation a significant difference in recurrence rates was no longer found. In premenopausal women, the DFI was not different for those with ER-positive compared to those with ER-negative tumors, not even in the first year of observation. However, in postmenopausal women, those with ER-positive tumors had a significantly longer DFI up to 3 years after initial treatment but not thereafter. There was no difference in DFI between the ER-positive and ER-negative groups when the tumor stage was taken into account. It is concluded that the ER status of the primary tumor affects prognosis only on the short term.
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  • 29
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    Breast cancer research and treatment 6 (1985), S. 241-248 
    ISSN: 1573-7217
    Keywords: cyclic nucleotides ; breast cancer ; tumor development ; DMBA rat mammary tumors ; prognostic factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The levels of cyclic adenosine 3′:5′-monophosphate (cAMP) and cyclic guanosine 3′:5′-monophosphate (cGMP) were studied in dimethylbenz(a)anthracene (DMBA)-induced mammary tumors of Sprague-Dawley rats and in human breast cancer. In the rat carcinomas, these levels were significantly lower than in non-malignant tissues when calculated on the basis of DNA content, but higher (cAMP) or equal (cGMP) when calculated on the basis of weight. In human breast cancer the cyclic nucleotide levels were higher than in non-malignant tissues according to both methods of calculation. No correlation was found in human carcinomas between the cyclic nucleotide levels and mitotic index, nuclear grade, tumor size, or lymph node involvement. The rat tumors were subclassified according to state of differentiation, mitotic index, and state of development. Not all the sub-groups had cAMP levels different from normal values. Differences in cAMP levels between the sub-groups could not be correlated with tumor growth rates and/or mitotic index. Thus, cyclic nucleotides may not be useful in prognosis of breast cancer.
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  • 30
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    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985) 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 31
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The σ-orbital manifold of cubane 1, as suggested by its PE spectrum, is divided into two sets separated by a 3 eV gap extending from ∼ -10.5 eV to ∼ -13.5 eV. Halogen substituents with np AO basis energies falling into this gap (e.g. Cl or Br) will, therefore, hyperconjugate appreciably with both sets. Interaction with the lower-lying set will lead to the usual destabilization (‘normal’ hyperconjugation), whereas interaction with the set above will necessarily lead to a ‘stabilization’ (‘inverted’ hyperconjugation). As a result the lone-pair ionization energies of Cl or Br substituted cubanes (derived from PE spectra) are much larger than naively expected for an alkyl halide containing as much as 8 C-atoms. In particular no significant shift of the eg-1 lone-pair bands in the PE spectra of 1,4-dichloro- and 1,4-dibromocubane can be detected with respect to the first ionization energies of the free atoms Cl and Br, or of HCl and HBr.
    Additional Material: 7 Ill.
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  • 32
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title sponge is shown to contain eight new sesquiterpenoids for which a common, unusual biogenetic origin is postulated. The compounds are shown to be: (-)-(1R*,4R*)-3-(3′-furyl)methyl-2-p-menthen-7-yl acetate ((-)-8b); two diols separated as the monoacetates (-)-(1S*,4R*)-3-(3′-furyl)methyl-l-hydroxy-2-p-menthen-7-yl acetate ((-)-13a) and the (-)-(1R*,4R*)-epimer (-)-13b, the two C(4)-epimeric 4-ethoxy-3-(1′(7′),2′-p-menthadien-3′-yl)methyl-2-buten-4-olides ((+)-14a and (-)-14b), (-)-3-(3′-furyl)methyl-7-nor-2-p-menthen-l-one ((-)-11), (-)-(3Z)-1-(3′-furyl)-4,8-dimethylnona-3, 7-dien-2-yl acetate ((-)-17), and (+)-3-(5′,7′-seco-2′(10′)-pinen-7′-yl)methylfuran ((+)-15).
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  • 33
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chemical synthesis and biological activities of a new α-melanotropin derivative are described. Nα-(5-Bromovaleryl)-Nα-deacetyl-α-melanotropin contains the 5-bromopentanoyl group as a chemical ‘handle’ in place of the acetyl group of the natural hormone. The synthesis involved a new protected intermediate which allowed the selective deprotection of either the Nα or Nα amino group. The title compound reacted with sodium thiosulfate to give Nα-deacetyl-Nα-(5-(sulfothio)valeryl)-α-melanotropin, a key intermediate for the preparation of tobaccomosaic virus/α-melanotropin disulfide conjugates. As a basis for the study of the conjugates, biological activities of the title compound on Cloudman S-91 mouse melanoma cell cultures (tyrosinase stimulation, binding, and cyclic AMP accumulation) were determined. They proved to be quite similar to the corresponding α-melanotropin activities. Differences in bindings may be explained by stronger hydrophobic interaction of the new derivative with the lipid phase of the target cell membranes.
    Additional Material: 9 Ill.
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  • 34
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    Helvetica Chimica Acta 68 (1985), S. 76-82 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The carbonyl group in lactones and, to a lesser extent, in lactams tends to show a C—C=O angle that is larger than the O—C=O or N—C=O angle, the difference increasing in magnitude as the ring size decreases. The observed trend provides information on ratios of force constants characterising the flexibility of the s-cis-ester group and may be interpreted in terms of incipient chemical reaction to -O—(CH2)n—C≡O+. Molecular orbital calculations (MINDO/3, MNDO, EH) for model compounds provide an electronic interpretation of this angle difference in terms of an anomeric interaction between the p-type lone pair on the carbonyl O-atom and the antibonding C-O or C-N orbital.
    Additional Material: 3 Ill.
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  • 35
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    Helvetica Chimica Acta 68 (1985), S. 110-118 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclic octa- and decapeptides have been prepared, and their ion selectivity in solvent polymeric membranes was studied. Cyclo(-LPro-DLeu-)5 behaves as an ionophore which selects Mg2+ over Ca2+ by a factor of 100. Cyclo(LPro-LLeu)5 induces selectivity in membranes for Mg2+ over Li+, Na+ and K+ by a factor of 400, 200 and 10, respectively, while selectivity of Mg2+ over Ca2+ is poor. Some evidence is presented which indicates that certain ionophores exhibit high selectivity for monovalent magnesium complexes.
    Additional Material: 6 Ill.
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  • 36
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Friedel-Crafts monoacylation of trans-η-[(1RS,2RS,4SR,5SR,6RS,7SR,8SR)-C,5,6,C-η:C,7,8,C-η-(5,6,7,8-tetramethylidene-2-bicyclo[2.2.2]octyl acetate)]-bis(tricarbonyliron) ((±)-5) is highly stereoselective and yields trans-η-[(1RS,2RS,4RS,5SR,6RS,7RS,8SR)-C,6-η,oxo-σ:C,7,8,C-η-(6,7,8-trimethylidene-5-((Z)-2-oxopropylidene)-2-bicyclo[2.2.2]octyl acetate)]-bis(tricarbonyliron) ((±)-8) which equilibrates with the trans-η-[(1RS,2RS,4RS,5SR,6RS,7RS,8SR)-C,5,6,C-η:C,7,8,C-η-(6,7,8-trimethylidene-5-((Z)-2-oxopropylidene)-2-bicyclo[2.2.2]octyl acetate)]-bis(tricarbonyliron) ((±)-9) on heating. Optically pure (-)-9 has been prepared from the corresponding optically pure alcohol (+)-4. The structure and absolute configuration of (-)-9 was established by single-crystal X-ray diffraction.
    Additional Material: 4 Tab.
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  • 37
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    Helvetica Chimica Acta 68 (1985), S. 155-161 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alkylation in the 2-Position of (2S, 4R)-4-Hydroxyproline with Retention of ConfigurationO-Acetyl-4-hydroxyproline (1b) is condensed with pivalaldehyde to give a single stereoisomer of the 2-(tert-butyl)-4-oxo-3-oxa-1-azabicyclo[3.3.0]oct-7-yl acetate (3). This is converted to the enolates 4 or 5, reactions of which with alkyl halides, aldehydes, and acetone (→6,9,10,11) are diastereoselective (lk-1,3-induction). Cleavage of the corresponding products furnishes the enantiomerically pure 2-deuterio-, 2-methyl-, 2-allyl-, and 2-benzyl-substituted 4-hydroxyprolines 2a-2d.
    Additional Material: 2 Tab.
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  • 38
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Steric Course of the Reaction of Enamines Derived from Open-Chain Aldehydes and Ketones with Nitro-olefins Yielding 2,3-Disubstituted 4-NitroketonesThe relative configuration of the nitro-ketone 12 obtained by the title reaction has been proved by a Baeyer-Villiger degradation and subsequent reduction to the amino-alcohol (±)-(u)-20, the relative configuration of which is identical with a sample prepared from 2-methyl-3-hydroxybutyrate of known configuration (Scheme 1). The stereochemical course of the title reaction is thus as predicted by our topological rule. It is assumed that the other nitro-ketones 13-18 described here are also formed by (lk)-combination of the trigonal centers of the educts (diastereoselectivity 〉 90%, see Formulae and Fig. 1). It is not possible to reverse this relative topicity by employing (Z)- instead of (E)-components of the starting materials, due to the reversibility of the primary step of these Michael additions (Schemes 2 and 3, and Fig. 2).
    Additional Material: 2 Ill.
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  • 39
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    Helvetica Chimica Acta 68 (1985), S. 207-211 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On singlet excitation (λ = 254 nm), the epoxydiene (E)-3 underwent (E)/(Z)-isomerization, electrocyclic ring closure of the diene side chain leading to the cyclobutenes 4A + B, and rearrangement to the cyclohexanones 5A + B. Compounds 5A + B were presumably formed in a series of processes including a 1,3-acyl shift of the homoconjugated ketone 8, arising from (Z)-3 by a 1,5-H-shift accompanied by cleavage of the C,O-bond of the oxirane.
    Additional Material: 1 Tab.
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  • 40
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using readily accessible 10-sulfonamido-isoborneols as regenerable, chiral auxiliaries, highly face-selective C-C-bond formations at Cα and Cβ of carboxylates could be conveniently achieved. Thus, conjugated additions of RCu to enoates (1→2) furnished, after saponification, β-substituted carboxylic acids 3 in 94-98% e.e. Similarly, propionates 12 yielded after deprotonation, enolate alkylation, and reductive ester cleavage the (R)-alcohols 15 in 78-98% e.e. The acid (+)-3e was converted to the pheromone (-)-11.
    Additional Material: 2 Tab.
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  • 41
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of the pentadentate ligand 2,6-bis(3-carboxy-1,2-dimethyl-2-azapropyl)pyridine yields a mixture of the racemic and meso-isomers which it was difficult to separate by column chromatography. When the cationic Co(III)-complex of this ligand was crystallized with hexafluorophosphate as anion, two distinct crystalline forms were produced. The complex of the racemic ligand, 1, has C2 symmetry and is a dihydrate; a = 8.999(8), b = 12.047(6), c = 20.65(1) Å, orthorhombic, space group Peen,Z = 4, R = 0.074 for 1439 observed reflections. The complex of the meso-ligand, 2, shows two independent molecules (2A and 2B) per asymmetric unit, both monohydrates with a resolved disordered H2O molecule in 2A; a = 10.109(4), b = 12.835(2), c = 16.651(3) Å, α = 89.5(1)°, β = 84.7(3)°, γ = 88.6(3)°, triclinic, space group P1, Z = 4, Rs = 0.054 for 4198 observed reflections. The coordination around the Co-atom is distorted octahedral in both complexes, with the coordinated H2O molecule trans to the pyridine N-atom. In the racemic form of the complex, 1, the pyridine ring is twisted about the Co-N(1) bond with respect to the plane defined by atoms Co, N(1), O(W1), N(2) and N(2P) by 17.2(2)°. In the meso-form of the complex, 2, the CH3 substituent C(8P) on atom C(4P), is now axial with respect to the 5-membered chelate ring. As a result of steric hinderance between atom O(1) and CH3(8P), the pyridine ring has been displaced from the best mean-plane formed by atoms Co, O(W1), N(2) and N(2P). The principal axis of the pyridine ring C(3)…N(1), makes an angle of 14.1(1)° (mean) with this plane. At the same time the pyridine ring is twisted about axis C(3)…N(1) with respect to this plane by 19.7(1)° (mean).
    Additional Material: 2 Ill.
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  • 42
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Halochromic Molecules. Spectrophotometric Investigation of the Acidobasic Behaviour of Substituted 6,6-Diphenyl-6H-chromeno[4, 3-b]indolizines and their Aza-analoguesSubstituted 6,6-diphenyl-6H-chromeno[4,3-b]indolizines form ring-opened, intensely coloured (diphenyl)-indolizinylcarbenium salts with acid. UV/VIS spectra of the coloured salts are discussed on the basis of VEPPPCI calculations. The ∊pH* curves in buffered MeOH/H2O solutions and the pK* values are determined. The title compounds undergo very complex protonation equilibria.
    Additional Material: 5 Ill.
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  • 43
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    Helvetica Chimica Acta 68 (1985), S. 72-75 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Displacements of 1H-NMR chemical shifs for caffeine in D2O solution as a function of concentration conform to the behaviour expected for pure dimer formation according to the equilibrium 2(caffeine)⇄(caffeine)2 with a statistical probability of at least 95%. Confidence limits reported earlier for the dimerisation constant of caffeine represent the real statistical dispersion in the experimental data and do not reflect a systematic error such as tetramer formation.
    Additional Material: 2 Ill.
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  • 44
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    Helvetica Chimica Acta 68 (1985), S. 104-109 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the AlBr3-catalyzed adamantane rearrangement in CS2 of 1,2-exo-trimethylenenorbornane (1) to 2-endo,6-endo-trimethylenenorbornane (3), hydride-ion abstraction occurs at C(6) from the exo-side. The kH/kD value for competition between 1 and 5 (Dexo-C(6)) was 1.58 ± 0.05, whereas no kinetic isotope effect was operative for competition between unlabeled 1 and 4 (Dendo-C(5)) and between 1 and 6 (Dendo-C(6)).
    Additional Material: 1 Tab.
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  • 45
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    Helvetica Chimica Acta 68 (1985), S. 95-103 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Racemic diaminosugars were easily obtained by a regio- and stereoselective three-step synthetis. In the first step, regiospecific hetero-Diels-Alder cycloadditions between 1,2-dihydropyridines 1a and 10 and nitrosobenzene led to the bicyclic compounds 2a and 11, respectively, cis-Glycol formation starting from these latter adducts, followed by hydrogenolysis of the N—O bond and by exhaustive acetylation of the OH-groups, led to the diaminolyxose 5, the diaminomannose 14 and the diaminoallose 15. When starting from benzyl 1,2-dihydropyridine-1-carboxylate (1b) and using the same reaction sequence, the racemic piperidine derivative 8 was obtained.
    Additional Material: 4 Tab.
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  • 46
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Isolation of Bafilomycin-A1-21-O-(α-L-rhamnopyranoside). Structural Determination by Chemical Correlation with Bafilomycin A1 and LeucanicidinFrom cultures of an actinomycete strain, the known antifungal and insecticidal antibiotic leucanicidin (1) and a hitherto unknown antifungal antibiotic, bafilomycin-A1-21-O-(α-L-rhamnopyranoside) (2), were isolated. The latter is spectroscopically closely related to 1 and bafilomycin A1 (3) and gave degradation products identical with compounds obtained by analogous degradation of 1 and 3.
    Additional Material: 5 Tab.
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  • 47
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    Helvetica Chimica Acta 68 (1985), S. 119-125 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An empirical force-field for carbenium ions has been incorporated in Allinger's MM2 programme. Structural parameters of secondary carbenium ions calculated by this method are compared with those obtained with Schleyer's BIGSTRN calculations. The strain changes occurring upon solvolysis of secondary p-toluenesulfonates are evaluated by means of this force-field and correlated with the rate constants for solvolysis. The equation for correlation of acetolysis, relative to cyclohexyl p-toluenesulfonate, of 28 kc substrates is ΔGrel+ = 0.67 ΔEst - 0.20 (r = 0.958).
    Additional Material: 4 Ill.
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  • 48
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation of the Enantiomerically Pure cis- and trans-Configurated 2-(tert-Butyl)-3-methylimidazolidin-4-ones from the Amino Acids (S)-Alanine, (S)-Phenylalanine, (R)-Phenylglycine, (S)-Methionine, and (S)-ValineIn contrast to α-hydroxy and α-mercapto carboxylic acids, simple α-amino acids do not form acetal-type derivatives (2, X = NH) with pivalaldehyde. For the generation of amino-acid-derived chiral, nonracemic enolates (cf. 3), and hence, for the α-alkylation of amino acids without racemization and without an external chiral auxiliary, the imidazolidinones 12-14 were prepared diastereoselectively. To this end, the methyl or ethyl esters of amino-acid hydrochlorides were first converted to N-methylamides of amino acids which in turn were condensed with pivalaldehyde to give (neopentylidenamino)amides (11). These Schiff bases could be cyclized either to trans-or to cis-imidazolidinones (12, 14 and 13, respectively), which were obtained in enantiomerically pure form after recrystallization. The enantiomeric purities were confirmed by HPLC with chiral stationary phases or by 1H-NMR spectroscopy in the presence of chiral shift reagents. The configurations (cis, trans) were assigned by NOE measurements on 300- or 360-MHz 1H-NMR spectrometers.
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  • 49
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    Helvetica Chimica Acta 68 (1985), S. 144-154 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enantiomerically pure cis- and trans-5-alkyl-1-benzoyl-2-(tert-butyl)-3-methylimidazolidin-4-ones (1, 2, 11, 15, 16) and trans-2-(tert-butyl)-3-methyl-5-phenylimidazolidin-4-one (20), readily available from (S)-alanine, (S)-valine, (S)-methionine, and (R)-phenylglycine are deprotonated to chiral enolates (cf. 3, 4, 12, 21). Diastereoselective alkylation of these enolates to 5,5-dialkyl- or 5-alkyl-5-arylimidazolidinones (5, 6, 9, 10, 13a-d, 17, 18, 22) and hydrolysis give α-alkyl-α-amino acids such as (R)- and (S)-α-methyldopa (7 and 8a, resp.), (S)-α-methylvaline (14), and (R)-α-methyl-methionine (19). The configuration of the products is proved by chemical correlation and by NOE 1H-NMR measurements (see 23, 24). In the overall process, a simple, enantiomerically pure α-amino acid can be α-alkylated with retention or with inversion of configuration through pivaladehyde acetal derivatives. Since no chiral auxiliary is required, the process is coined ‘self-reproduction of a center of chirality’. The method is compared with other α-alkylations of amino acids occurring without racemization. The importance of enantiomerically pure, α-branched α-amino acids as synthetic intermediates and for the preparation of biologically active compounds is discussed.
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  • 50
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: tert-Butyl α,β-dioxobutyrate (hydrate; 1d) undergoes, at medium or high pH, the benzilic-acid rearrangement with exclusive 1,2-shift of the COO(t-Bu) group; the same is true for the corresponding isopropyl ester 1c and ethyl ester 1b at high pH, whereas at lower pH, the overall picture of these reactions is complicated by concurrent hydrolysis of the ester, followed by a 1,2-shift of the COO- group. Consequently, the shift of these electron-attracting groups cannot be considered to be systematically disfavoured (compared, e.g., with alkyl-group shifts). Kinetic measurements of the rearrangement show for both esters (as well as for the analogous ethyl ester 1b, and also for ethyl 3-cyclopropyl-α,β-dioxopropionate (4)) a characteristic rate profile: at relatively low pH, k is proportional to [HO-], approaching saturation with increasing [HO-] (interpreted as complete transformation of the substrate into the hydrate monoanion), which is followed at higher pH by another rate increase with k proportional to [HO-] (probably due to the reaction of the hydrate dianion). The similarity of k values for 1b-d shows that in the shift of COOR steric hindrance caused by R is negligible.
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  • 51
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On n,π*- as well as on π,π*-excitation, the 4,5-epoxy-α-ionones (E)-1, (E)-2, and (E)-3 undergo (E)/(Z)-isomerization and subsequent γ-H-abstraction leading to the corresponding 4-hydroxy-β-ionones (E/Z)-9, (E/Z)-13, and (E/Z)-17 as primary photoproducts. On photolysis of (E)-3, as an additional primary photoproduct, the β,γ-unsaturated σ,∊-epoxy ketone 18 was obtained. The other isolated compounds, namely the 2H-pyrans 10A + B and 14A + B as well as the retro γ-ionones 11 and 15A + B, represent known types of products, which are derived from the 4-hydroxy-β-ionones (E/Z)-9 and (E/Z)-13, respectively.
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  • 52
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    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 391-402 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The photolability of the antitumor antibiotic hedamycin (1) was investigated by irradiation in different solvents in the presence or in the absence of oxygen. The products formed were separated chromatographically and their structures determined by NMR spectroscopy. Photolysis of 1 in the presence of oxygen gave only one isolable product, photohedamycin A (3), where ring E of hedamycin had been transformed into an enol ether. The reaction in the absence of oxygen yielded the photohedamycins B, C, and D (5, 6, and 7, respectively). In these compounds, one of the epoxides of hedamycin had been opened reductively, and in photohedamycin D (7) the substituent at C(8) - originally ring E of hedamycin - was now acyclic. In addition to these compounds, the photolyses yielded a large number of unstable minor products, which could not be isolated.
    Additional Material: 2 Ill.
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  • 53
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New procedures are described for the synthesis of α,β-ethylenic and acetylenic aldehydes from 2-butene- and 2-butyne-1,4-diol, respectively (see Scheme 1). These are applied to the preparation of a particular δ-acetylamino-α,β-ethylenic aldehyde ((E)-5) as well as of its acetylenic analogue 15. On heating in the presence of a silyl enol ether, the former undergoes a complete dehydrative cyclization affording the N-acetyl-1,2-dihydropyridine 19. The addition of HCl to aldehyde (E)-5 results in the production of the 4-chloro-1,2,3,4-tetrahydropyridine 22 which is hydrolyzed to the corresponding alcohol 23 on silica gel. Similarly, the addition of HCl or HBr to the δ-acetyl-amino-α,β-acetylenic aldehyde 15 leads to the previously unknown 4-halo-1,2-dihydropyridines 26; these are easily hydrolyzed to the 2,3-dihydro-4(1H)-pyridinone 27. The ring-forming process involves a N-acyl N,O-hemiacetal as intermediate which is eventually dehydrated.
    Additional Material: 2 Tab.
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  • 54
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 450-455 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The polar effects of substituents on reactivity in oxidation of 2-substituted anthracenes with tert-butyl hydroperoxide (TBHP)/Rh(PPh3)3Cl have been investigated and compared with those obtained with TBHP/VO(acac)2 and chromic acid. The anthracene reactivities obtained from competition experiments are correlated with Hammett's σp-constants. The P-values are -2.60 for chromic acid and 0.72 for TBHP/VO(acac)2. A poor correlation with p = -0.17 (r = 0.756) was obtained for TBHP/Rh (PPh3)3Cl. It is concluded that the Rh-catalyzed reaction does not consist in electrophilic oxygen transfer to the anthracene.
    Additional Material: 1 Ill.
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  • 55
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 465-474 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of 3,3-Dimethylperhydro-1,4-diazepin-2,5,7-triones from 3-Dimethylamino-2,2-dimethyl-2H-azirine and Malonic Acid MonoamidesReaction of the aminoazirine 1 and malonic acid monoamides 5 in CH3CN yielded triamides of type 6 (Scheme 2), which were transformed to the corresponding phenylthioates 9 by treatment of a solution of 6 and thiophenol in CH3CN with HCl (Scheme 4). Cyclization of 9 to give the 1,4-diazepin-2,5,7-trione of type 10 was achieved with NaH in toluene at about 90°. It has been shown that 2-oxazolin-5-ones are intermediates in the selective cleavage of the therminal amide function of 6 (Scheme 3).
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  • 56
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nature and Stability of Some Metallic Complexes of Dinucleating Cryptands in Solution. I. A Polyazapolyoxa Cylindrical Macrotricycle and its Monocyclic SubunitpH-metry and UV spectrophotometry were used to study the complexing properties of the cylindrical macrotricycle, 1,7,13,19-tetraaza-4,16-dioxa-10,22,27,32-tetraoxatricyclo[17.5.5.5]tetratriacontane (1) and of its constitutive monocyclic subunit, 1,7-diaza-4,10-dioxacyclododecane (2) with some transition and heavy metal cations (Cu2+, Co2+, Ni2+, Zn2+, Cd2+, Pb2+, Ag+), in aqueous medium 0.1M Et4NClO4, at 25°. The protonation constants of the ligands as well as the nature and the stabilities of the complexes formed in the pH-regions studied were determined. The tricycle 1 only formed dinuclear M2L complexes with Cu2+, Zn2+, and Ag+, accompanied in the latter case by a protonated mononuclear MLH species, and with Cu2+ and Zn2+ at high pH-values by dinuclear hydroxo complexes. Only mononuclear complexes were evidenced with the other cations, ML being accompanied either by protonated or hydroxy mononuclear species. The mononuclear complexes of 1, when they existed, were more stable than the corresponding complexes of 2, except for cobalt which formed complexes of comparable stability with both ligands. In the other cases (Cd2+, Pb2+, Ag+), the stability differences between the complexes of 1 and 2 increased with the size of the cation.
    Additional Material: 3 Ill.
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  • 57
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Planarisation of Tetracoordinate Carbon Atom, Synthesis of the Brigded all-cis-[5.5.5.5]Fenestrane 13-Oxapentacyclo[5.5.2.11,7.04,15.010,15]pentadecan-14-oneThe synthesis of the ketolactone 23 from (Z,Z)-1,5-cyclooctadiene is reported. Transannular carben insertion, achieved via photolysis of the deprotonated (2,4,6-trisisopropylphenylsulfonyl)hydrazone of 23 gives the bridged all-cis-[5.5.5.5]fenestrane 3.
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  • 58
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Water exchange on hexaaquavanadium (III) has been studied as a function of temperature (255 to 413 K) and pressure (up to 250 MPa, at several temperatures) by 17O-NMR spectroscopy at 8.13 and 27.11 MHz. The samples contained V3+ (0.30-1.53 m), H+ (0.19-2.25 m) and 17O-enriched (10-20%) H2O. The trifluoromethanesulfonate was used as counter-ion, and, contrary to the previously used chloride or bromide, CF3SO3- is shown to be non-coordinating. The following exchange parameters were obtained: kex298 = (5.0 ± 0.3) · 102 s-1, ΔH* = (49.4 ± 0.8) kJ mol-1, ΔS* = -(28 ± 2) JK-1 mol-1, ΔV* = -(8.9 ± 0.4) cm3 mol-1 and Δβ* = -(1.1 ± 0.3) · 10-2 cm3 mol-1 MPa-1. They are in accord with an associative interchange mechanism, Ia. These results for H2O exchange are discussed together with the available data for complex formation reactions on hexaaquavanadium(III). A semi-quantitative analysis of the bound H2O linewidth led to an estimation of the proportions of the different contributions to the relaxation mechanism in the coordinated site: the dipole-dipole interaction hardly contributes to the relaxation (less than 7%); the quadrupolar relaxation, and the scalar coupling mechanism are nearly equally efficient at low temperature (∼ 273 K), but the latter becomes more important at higher temperature (75-85% contribution at 360 K).
    Additional Material: 5 Ill.
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  • 59
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    Helvetica Chimica Acta 68 (1985), S. 534-544 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Spontaneous Opening of the Pyrimidine Ring of Pyrrolo[2,3-d]pyrimidines after Intramolecular AcylationPhase-transfer alkylation of 4-methoxy-2-methylthio-7H-pyrrolo[2,3-d]pyrimidine (2) with ethyl 3-bromopropionate leads regioselectively to the ester 3a. After displacement of its methylthio group and saponification of the ester function, the acid 3e is obtained which can be transferred to the functionalized deazahypoxanthine 3f by either treatment with dry HBr/glacial AcOH or by nucleophilic displacement of the 4-methoxide. Reaction of 3f with a H2O-soluble carbodiimide results in an intramolecular acylation at N(1) by the activated ester; the intermediate 4 undergoes spontaneous hydroxylation and subsequent opening of the pyrimidine ring under formation of the pyrrolo[1,2-a]pyrimidine derivative 6. Its structure was proved by X-ray analysis. Subsequent deformylation of 6 in alkaline medium leads to the compound 7 in almost quantitative yield.
    Additional Material: 2 Ill.
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  • 60
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two new saponins, β-D-glucopyranosyl 3-O[O-βD-xylopyranosyl-(1→3)-O-(β-D-glucopyranosyluronic acid)]oleanolate (1) and 3-O-[O-β-D-xylopyranosyl-(1→3)-O-(β-D-glucopyranosyluronic acid)]oleanolic acid (2), have been isolated from the tubers of Talinum tenuissimum. The structures have been established mainly by 13C-NMR and FAB-MS. The monodesmosidic saponin 2 exhibits very strong molluscicidal activity against the schistosomiasis-transmitting snail Biomphalaria glabrata.
    Additional Material: 1 Tab.
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  • 61
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The transverse relaxation rate of H2O in Al(H2O)63+ has been measured as a function of temperature (255 to 417 K) and pressure (up to 220 MPa) using the 17O-NMR line-broadening technique, in the presence of Mn(II) as a relaxation agent. At high temperatures the relaxation rate is governed by chemical exchange with bulk H2O, whereas at low temperatures quadrupolar relaxation is prevailing. Low-temperature fast-injection 17O-NMR was used to extend the accessible kinetic domain. The samples studied contained Al3+ (0.5 m), Mn2+ (0.2-0.5 m), H+ (0.2-3.1 m) and 17O-enriched (20-40%) H2O. Non-coordinating perchlorate was used as counter ion. The following H2O exchange parameters were obtained: kex298 = (1.29 ± 0.04) s-1, ΔH* = (84.7 ± 0.3) kJ mol-1, ΔS* = +(41.6 ± 0.9) J K-1 mol-1, and ΔVex* = +(5.7 ± 0.2) cm3 mol-1, indicating a dissociative interchange, Id, mechanism. These results of H2O exchange on Al(H2O)63+ are discussed together with the available complex-formation rate data and permit also the assignment of Id mechanisms to these latter reactions.
    Additional Material: 4 Ill.
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  • 62
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    Helvetica Chimica Acta 68 (1985), S. 571-580 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1-O-Acetyl-1-O-demethylcolchicine, and acylated 1-O,2-O-didemethylthiocolchicines, in contrast to 2-O-acetyl-, 2-O,3-O-diacetyl- and 3-O-acetyl analogs, showed after standing in CHCl3 solution significant changes in optical rotation, a duplication of 1H-NMR signals, and the formation of new isomers on TLC. Solid-state X-ray diffraction of O-acetylated colchinoids and thio analogs, showed out of planar arrangements of the aromatic substituents, but the analysis could not help to explain the structures of the newly formed isomers in CHCl3 solution.
    Additional Material: 3 Ill.
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  • 63
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    Helvetica Chimica Acta 68 (1985), S. 563-570 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Phase-transfer glycosylation of 4-methoxy-1H-pyrazolo[3,4-d]pyrimidine with the 2-deoxyribofuranosyl chloride 9 formed the N(1)-β-nucleoside 10a as main product (39%). As by-products the α-D-anomer 11a (7%) and the N(2)-isomer 12a (18%) were isolated. Assignment of these isomers was made on the basis of their 1H- and 13C-NMR spectra. Removal of the sugar-protecting groups yielded the 4-methoxy-nucleosides 10b, 11b, and 12b, respectively. Nucleophilic displacement of the 4-MeO-group gave the 2-deoxyribofuranosides 1-4 of allopurinol and 4-amino-1H-pyrazolo[3,4-d]pyrimidine.
    Additional Material: 3 Tab.
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  • 64
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    Helvetica Chimica Acta 68 (1985), S. 606-609 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Liquid crystals with negative Δ∊ can be obtained by incorporating a cyano group in the terminal alkyl substituent or in an ethylene bridge between the cyclic units of the rigid core. The clearing points of such compounds are higher than those of the corresponding derivatives where the cyano group is laterally attached to a phenyl moiety. In compounds where both cyclic units of the rigid core are cyclohexyl, this type of substitution leads to an optimal contribution to ∊⊥ in contrast to the cyanophenyl derivatives.
    Additional Material: 2 Tab.
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  • 65
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    Helvetica Chimica Acta 68 (1985), S. 610-613 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 3,7,10-Tribenzyl-3,7,10-triaza[3.3.3]propellane (4a), 3,7-dibenzyl-10-phenyl-3,7,10-triaza[3.3.3]propellane (4c), 3,7-dibenzyl-10-(p-tolyl)-3,7,10-triaza[3.3.3]propellane (4b), and 3-oxa-7,10-diaza[3.3.3]propellane (6) have been prepared.
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  • 66
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    Helvetica Chimica Acta 68 (1985), S. 618-622 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The glycopentapeptide H-(GlcNAcβ1-)Asn-Glu-Thr-Ile-Val-OH (10) representing the partial sequence A80-A84 of human fibroblast interferon was synthesized using the newly developed allyl-ester protection of carboxy functions. The allyl esters, which are stable to acids and to bases, can be cleaved under very mild, neutral conditions using tris(triphenylphosphine)rhodium(I) chloride or tetrakis(triphenylphosphine)palladium(0) as a catalyst. This synthetic method opens up a preparative route to glycopeptide model structures of glycoproteins of high biological interest.
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  • 67
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    Helvetica Chimica Acta 68 (1985), S. 651-660 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rate constants (log k) for the solvolysis of 4e-substituted 2e- and 2a-adamantyl p-nitrobenzenesulfonates 14 and 15, respectively, in 80% EtOH correlate linearly with the respective inductive substituent constants σIq. Therefore, relative rates are controlled by the I effect of the substituents at C(4). The derived reaction constants, or inductivities, ρI of -0.80 and -0.64 for the series 14 and 15, respectively, are far smaller than those previously determined for 6-substituted 2-norbornyl and 2-bicyclo[2.2.2]octyl sulfonates, in which the partial structure containing the substituent and the leaving group is the same. The ratio of the retained and inverted adamantanols obtained upon hydrolysis of the series 14 falls from 2.85 for R = CH3 to ca. 1 for R = CN, i.e. as the substituent at C(4) becomes more electron-attracting. In the 2a-series 15 this ratio is uniformly higher. These findings confirm that the 2-adamantyl cation is weakly bridged and that through-space induction in carbocations involves graded bridging of the cationic center by neighboring C-atoms.
    Additional Material: 2 Ill.
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  • 68
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The all-light-atom X-ray crystal-structure analysis of cyclosporin A (1), a cyclic undecapeptide containing seven N-methylated amino acids, reveals a conformation very similar to that of the previously analysed iodo derivative which is characterised by a twisted β-pleated sheet involving the residues Me-Val-11, MeBmt-1, Abu-2, Sar-3, MeLeu-4, Val-5, MeLeu-6, and Ala-7. The β-bend at Sar-MeLeu-4 is of type II′, and the loop of the residual amino acids involves a cis-peptide bond between MeLeu-9 and MeLeu-10. The NH proton of D-Ala-8 closes a yi-bend with a H-bond to the MeLeu-6 CO group. The crystal was grown from acetone. A closely similar backbone conformation in apolar solvents such as CDCl3 or C6D6 has been derived from the interpretation of the NMR spectral parameters (homo- and heteronuclear NOE effects, coupling constants, chemical-shift values of the C-, H-, and N-atoms). A minor variation in the backbone conformation between crystal and solution is observed in the region of D-Ala-8, where in solution a 3-center H-bond is established between the NH of D-Ala-8 und the carbonyl O-atoms of both MeLeu-6 (yi-turn) and D-Ala-8 (C5-bend). A recently proposed technique to identify intramolecular H-bond via heteronuclear NOE from NH proton to carbonyl C-atoms is critically analysed. The main difference between crystal and solution conformations lies in the orientation of the side chains of the unusual amino acid MeBmt (χ1 = +60° in solution, -168° in the crystal) and of MeLeu-10 (X1 = -60° in solution, +60° in the crystal). The differences in crystal and solution are caused by the break of the intermolecular H-bond of the OH group of MeBmt on dissolution of the crystal. The bifurcated H-bond of D-Ala-8 twists the backbone in this region. Molecular modeling demonstrates that this is the origin of the change in the side chain conformation of MeLeu-10. The intramolecular flexibility in the crystal indicated by the thermal parameters obtained from the X-ray refinement, and in solution by an analysis of spin-lattice relaxation times in the NMR experiments, indicate a fairly rigid backbone and fixed conformations for all the side chains except for that of Abu-2 and the distal atoms of MeBmt.
    Additional Material: 13 Ill.
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  • 69
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    Helvetica Chimica Acta 68 (1985), S. 581-583 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structure of the title compound obtained from 2(1H)-quinoxalinone oxime by the template effect of Co(II) and Ni(II) ion has been determined by three dimensional X-ray analysis.
    Additional Material: 2 Ill.
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  • 70
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    Helvetica Chimica Acta 68 (1985), S. 584-591 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photochemical Syntheses of 3-Oxazolines which Possibly Exhibit Hypoglycemic ActivityReactions of photochemically generated benzonitrile methylides 2 with carbonyl compounds 3 yielded 3-oxazolines of the types 5 and 6 (Scheme 1). Photooxidation of 5-[p-(dimethylamino)phenyl]-2,2-dimethyl-4-phenyl-3-oxazoline (5a) gave 4′-(2,2-dimethyl-4-phenyl-3-oxazolin-5-yl)-N-methylformanilide (6r) which could be transformed to 2,2-dimethyl-5-[p-(methylamino)phenyl]-4-phenyl-3-oxazoline (6s) by photodecarbonylation. Thirty 3-oxazolines of types 5 and 6 have been synthesized and tested by oral and/or intraperitoneal administration to starved rats and obese-hyperglycemic mice.
    Additional Material: 5 Tab.
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  • 71
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    Helvetica Chimica Acta 68 (1985), S. 600-605 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photochemical and Chemical Syntheses of Biologically Active 3-OxazolinesUsing the photoreaction of 2H-azirines with carbonyl compounds, the 2,2-dimethyl-3-oxazolines 5a, 5b, and 6a have been obtained which bear a mono- or dichlorophenyl substituent at C(4) of the five-membered heterocycle and pyridyl at C(5). These compounds exhibit interesting activities against phytopathogenic fungi. Because 6a had been selected for field testing, its photochemical preparation was supplemented by a chemical synthesis. However, the overall performance of 6a in the field was inferior to some of the recently introduced agricultural fungicides of the ergosterol biosynthesis inhibitor type. Although 16 additional 3-oxazolines with varied substituents have been prepared, the fungicidal activity found with 6a could not be improved.
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  • 72
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    Helvetica Chimica Acta 68 (1985), S. 592-599 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Reactions of 5-[p-(Dimethylamino)phenyl]-2,2-dimethyl-4-phenyl-3-oxazolineThe title compound 8 has been synthesized in a one-pot reaction of 4′-(dimethylamino)benzoin (4) with 2-propanone and NH3. The preparation of the intermediate 4 from 3 is the first example of an acid-catalyzed transformation of the stable benzoin 3 into the corresponding less stable benzoin 4. Structures and yields of various by-products occurring under different reaction conditions during the synthesis of 8 from 4 are given. The O-atom of the 3-oxazoline ring in 8 could be replaced by S from P2S5 yielding the 3-thiazoline 14. Separation of the enantiomers of the racemate 8 could only be performed by transforming them into the trimethylanilinium salts 8b and 8c of (-)- and (+)-10-camphorsulfonic acid, respectively. Solid NaOAc in boiling toluene caused the precipitation of the 10-camphorsulfonic acids from the quaternary ammonium salts as sodium salts and the removing of the third methyl group from the quaternary ammonium salts as AcOMe to give the enantiomers (-)-(5S)-8 and (+)-(5R)-8. Their absolute configurations are deduced from an X-ray analysis of 8b.
    Additional Material: 2 Ill.
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  • 73
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Oxidation of the title compound with m-chloroperbenzoic acid affords a keto-lactone, two bis-lactones and a bis-spirolactone, in varying amounts depending upon the reaction conditions. The structures were established by means of X-ray diffraction, 1H- and 13C-NMR spectroscopy.
    Additional Material: 2 Ill.
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  • 74
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    Helvetica Chimica Acta 68 (1985), S. 623-634 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Substituted CyclononatetraenesIn the course of an exploration of possible synthetic pathways to nonafulvenes, a series of 1-substituted cyclononatetraenes (CNT) 4b-1 have been prepared in yields of about 60%. Their structures follow from spectroscopic data as well as from the quantitative valence isomerisation to 1-endo-substituted cis-3a, 7a-dihydroindenes 8. Both all-cis-CNT- 1 and cis,cis,cis,trans-CNT- 2 have been used as nucleophiles. Whereas 2 is normally more nucleophilic than 1, the yield of cyclononatetraenes 4 prepared with 2 may be reduced due to by-products such as 9 and 10.
    Additional Material: 2 Ill.
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  • 75
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 1H-, 13C-, and 15N-NMR spectra of the immunosuppressive cyclic undecapeptide cyclosporin A (1) have been analyzed at 300 MHz in CDCl3, C6D6, and mixtures of these solvents. A combination of different homo- and heteronuclear two-dimensional NMR techniques enable complete assignment of all H-, C- and 4 N-signals. Recognition of the proton spin systems has been achieved via 1H,1H-COSY and double-quantum-1H-NMR spectroscopy. NOESY spectra yield some sequence assignments, but two techniques using coupling across amide bonds have been applied to get independent assignments of all amino acids in the sequence: (i) An 1H,1H-COSY spectrum optimized for small coupling constants enables the detection of long-range couplings from N-methyl groups to both α-protons attached to that amide bond. (ii) An 1H, 13C-COSY spectrum optimized for C,H-long-range couplings (J = 5 to 10 Hz) to the eleven CO groups again yields coupling to both α-protons attached to that amide bond. Additionally these two experiments yield the assignment of N-methyl protons and carbonyl C-atoms. Normal and relayed 1H,13C-COSY in both solvents have been applied to assign all C-atoms via their directly attached and remote protons. An 1H,13C-COLOC spectrum at 500 MHz in CDCl3, which uses H,C-long-range couplings confirms the assignment of all proton spin systems as well as the C-signals of each individual amino acid. Ambiguities in the assignment of the C(δ)'s of MeLeu have thus been removed. An 1H,15N-COSY spectrum enables the assignment of the 4 NH N-atoms.
    Additional Material: 13 Ill.
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  • 76
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and photolyses of the epoxydiene (E)-5 are described. On triplet excitation (λ 〉 280 nm, acetone), (E)-5 undergoes initial cleavage of the C(5)—O bond leading to the intermediate c. Presumably an H-shift (c → e) followed by the fragmentation of the 1,4-diradical e leads (via the enol 37) to the diketones (E)-6 and (Z)-12. Alternatively cleavage of the C(6)—C(7) bond of c furnishes the diradical intermediate d which reacts by recombination leading to (E)-13A + B, 16, and 17A + B, or by an H-shift to the enol intermediate 38. The latter undergoes an aldol-type reaction to (E/Z)-14A + B and (E/Z)-15A + B, as well as a photochemical [2 + 2]-cycloaddition to 18. On singlet excitation (λ = 254 nm, MeCN), (E)-5 undergoes photocleavage to the carbene intermediates f and g. The vinyl carbene f reacts with the adjacent double bond furnishing the cyclopropene 22 as the main product. From the carbene intermediate g, compounds 23, 24, and 25 arise by carbene insertion into the neighboring C—C or C—H bond. Furthermore, the diastereomer of the starting material, the epoxydiene (E)-20, is formed via the ylide intermediate h.
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  • 77
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    Helvetica Chimica Acta 68 (1985), S. 724-733 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The molecular structure of pyroergotamine has been determined by single-crystal X-ray diffraction analysis to be the pyruvoyldiketopiperazine 1. The diketopiperazine ring exists in a folded or boat conformation, with a dihedral angle of 40° between the two almost planar peptide units. The R-group of the phenylalanine residue occupies a quasi-axial position of the diketopiperazine ring, while that of the proline residue is in a quasi-equatorial position. Puzzling spectroscopic and chemical properties of the compound can be rationalised in terms of crowding within the molecule.
    Additional Material: 3 Ill.
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  • 78
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    Helvetica Chimica Acta 68 (1985), S. 715-723 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electronic properties of dopamine were studied by the ab initio STO-3G MO method. The molecular electrostatic potential (MEP) around the aromatic ring and the catechol group remains practically the same in 3,4-dihydroxytoluene (a model compound) and in neutral dopamine examined in its two extended conformations, namely that found in the crystal (side-chain and aromatic ring almost perpendicular) and the one corresponding to 2-amino-6,7-dihydroxytetralin (6,7-ADTN) (side-chain and aromatic ring almost coplanar). In protonated dopamine and in dopamine hydrochloride, the electrostatic potential of the catechol moiety is overshadowed by the positive charge, but the main features remain discernible. The catechol moiety was examined in its two coplanar conformations containing a ‘flip-flop H-bond’. The electrostatic potential around the catechol moiety is quite complex, with alternating positive and negative maxima. At increasing distances above and away from the catechol moiety, only two peripheral maxima, one negative and one positive, remain perceptible. The ‘flip-flop’ mechanism results in an approximate interchange of these two potential maxima, a fact which tends to level out the structural differences between the α- and β-rotamer of dopamine. Based on these results and on the structure of rigid agonists, some pharmacophoric features of dopamine agonists are proposed.
    Additional Material: 8 Ill.
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  • 79
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    Helvetica Chimica Acta 68 (1985), S. 760-769 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Hydrolysis of 4-Substituted 2-Adamantyl p-NitrobenzenesulfonatesSeveral 4e -substituted 2e- and 2a-adamantyl p-nitrobenzensulfonates have been prepared by new routes. Their hydrolysis products are described.
    Additional Material: 2 Tab.
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  • 80
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In presence of a strong base, the 13-membered cyclic compound 3 yielded, by loss of acetonitrile or its equivalent, the bicyclic product 5 instead of the 17-membered compound 4 as expected (Scheme 2). Investigation of model compounds (Scheme 4) and of model reactions (Schemes 5 and 6) led to the conclusion that the reaction proceeds via an intermediate formaldehyde imine; a Schiff base, e.g. 3b (Scheme 5), which reacts intra- and intermolecularly with a nucleophile to form a Mannich-type product. It seems to be a general principle that N-substituted 3-aminopropanenitrile and 2-aminoacetonitrile derivatives behave in the presence of a strong base as Schiff -base equivalents (Schemes 5 and 6).
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  • 81
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    Helvetica Chimica Acta 68 (1985), S. 777-788 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The biradical 2,2-dimethyl-1,3-perinaphthadiyl (a) was generated from two different precursors, the naphthocyclopropane 1 and the azo compound 2, and from each by three different pathways (pyrolysis, direct photolysis, and triplet sensitization, Scheme 1). The combined evidence from flash photolysis, low-temperature spectroscopy, and product analyses provides a detailed mechanistic picture of the formation and decay of this reactive intermediate which is persistent at 77 K in the triplet ground state (3a) and rather long-lived (400 μs) at room temperature. When formed in its lowest singlet state (1a), the biradical is too short-lived to undergo intersystem crossing to 3a or bimolecular reactions. Thus, 3a is formed exclusively from the excited triplet state of the precursor compounds, 31* or 33*. The monomolecular decay of 3a is retarded by the spin barrier; 3a initiates the polymerization of acrylonitrile and is trapped by 3O2.
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  • 82
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    Helvetica Chimica Acta 68 (1985), S. 818-818 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 83
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    Helvetica Chimica Acta 68 (1985), S. 819-820 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 84
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An overall enantioselective substitution of the R-group of an α-hydroxy- or α-amino acid 1 [R—CH(XH)COOH] by another R-group is possible through heterocycles 2 obtained from 1 with pivaladehyde (1 → 7). The rac- and the (S)-(+)-heterocycles 8 (title compounds of type 5) are prepared from glycine and O-benzyl-(S)-serine, respectively. Their enolates (cf. 9, type 6) are alkylated with iodomethane, iodobutane, 2-iodopropane, benzyl bromide, and acetone to give the trans-disubstituted imidazolidinones 10 with ≥ 95% diastereoselectivity. The configuration of the products is established by chemical correlation with alanine, phenylalanine, and valine.
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  • 85
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactivity of Carbonyl Compounds with Ketenes in the Presence of Titanium or Zirconium AlkoxidesThe reaction of ketene or dimethylketene with aldehydes or ketones in the presence of titanium or zirconium alkoxides gives essentially β-hydroxyesters. By polyinsertion of ketene and aldehydes in the Ti—O bond, di- tri- and tetraesters are formed. An excess of ketene produces acetyl derivatives of esters and 6-alkyl-3,4,5,6-tetrahydro-2,4-pyrandiones.
    Additional Material: 2 Tab.
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  • 86
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    Helvetica Chimica Acta 68 (1985), S. 961-968 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Selective Preparation of l- or u-Aldols from Ethyl Trityl Ketone and Aromatic Aldehydes through Lithium and Aluminium Enolates, RespectivelyThe ethyl trityl ketone (1) is deprotonated to the (Z)-enolate 2 which adds to aromatic aldehydes with relative topicity ul to give the aldols 3(-78°, THF, kinetic control). If, on the other hand, 1 is heated with trimethylaluminium in toluene, the aluminium enolate formed combines with aromatic aldehydes and with cinnamic aldehyde with opposite relative topicity (lk) to the aldols 5 (+20°, toluene, 2 d, precipitation of the aluminium aldolate 4, thermodynamic control). The mechanism is discussed (cf. Fig. 1). The adducts to benzaldehyde (3a, 5a), furfural (3f, 5f), and cinnamaldehyde (3i, 5i) are O-(2-methoxyethoxy)methyl (MEM) protected and cleaved by lithium triethylborohydride to the 1,3-diol derivatives 9-11 with a free primary and a protected secondary OH-group. Analogous conversions of 1 and other ketones may also be diastereoselective, but turned out to be of less preparative value (see 6-8, 12).
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  • 87
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Treatment of the chloro-nitro-ribofuranose 7 with KPO(OMe)2 gave the O-amino phosphate 8 (5 %) and the nitrile 9 (62 %). Compound 9 was also obtained by the reaction of 8 with KPO(OMe)2, and its structure was established by X-ray analysis. Treatment of the chloro-nitro-mannofuranose 10, the bromo-nitro-ribofuranose 14, or the bromo-nitro-mannofuranose 16, respectively, with the K or Na salt of HPO(OMe)2 lead also to O-amino phosphates and nitriles. The (1-C-nitroglycosyl)phosphonate 22 was obtained (21 %) together with the nitrile 21 (51 %) from the chloro-nitro-mannofuranose 10 and KPO(OEt)2. The reaction of the 1-C-nitroglycosyl sulfone 25 (NO2-group endo) with KPO(OEt)2 gave the (1-C-nitroglycosyl)phosphonate 22 (61%) and the nitrile 21 (11 %), whilst the anomeric sulfone 26 (NO2-group exo) gave 22 (15 %) and 21 (58 %). In the presence of [18] crown-6, a mixture of the anomers 25 and 26 gave the (1-C-nitroglycosyl)phosphonate 22 in 67 % yield together with 21 (13 %). These findings are rationalized as the result of a competition between a nucleophilic attack of the dialkyl-phosphite anions on the NO2-group leading ultimately to the nitrile 21 and a single-electron transfer reaction leading to the (1-C-nitroglycosyl)phosphonate 22.
    Additional Material: 1 Tab.
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  • 88
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    Helvetica Chimica Acta 68 (1985), S. 1033-1053 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Crystal structures have been determined of methyl trans-1-hydroxy-6-nitro-3-oxobicyclo[4.4.0]decane-2-carboxylate (19), cis-3-methyl-6-nitro-2-oxabicyclo[4.4.0]decan-1-ol (2), cis-7-hydroxy-1-nitrobicyclo[5.4.0]undecan-9-one (13), and the medium-ring compounds 2-acetyl-4-nitrocyclooctanone (9), methyl 5-nitro-2-oxocyclooctane-carboxylate (4), 2-acetyl-4-nitrocyclononanone (11), 2-acetyl-4-nitrocyclodecanone (15), benzyl 5-nitro-2,11-dioxocycloundecanecarboxylate (24), methyl 5-nitro-2,12-dioxocyclododecanecarboxylate (21), and 8-nitro-11-oxo-13-tridecanolide (7), which are intermediates, side products, or end products of the ‘Zip’ ring-enlargement reaction. The conformations of most of the medium-ring compounds are very similar to equal-sized ring compounds previously determine by other authors.
    Additional Material: 25 Ill.
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  • 89
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 2,5-dimethylidene-3,6-bis[(Z)-(2-nitrophenyl)sulfenylmethylidene]-7-oxabicyclo[2.2.1]heptane (13) can be used to generate polyfunctional and multicyclic molecules with high regio- and stereoselectivity via two successive Diels-Alder additions using two different dienophiles. This principle has been applied to the synthesis of (±)-11-deoxydaunomycinone (7), the aglycone of an important antitumor drug. The 2,3-didehydroanisole adds to 13 and gives the monoadduct 14 with high regioselectivity. No trace of bis-adduct is observed. The 1,4-epoxy-1,2,3,4-tetrahydro-5-methoxy-3-methylidene-2-[(Z)-(2-nitrophenyl)sulfenylmethylidene]anthracene (15) obtained on treating 14 with K2CO3 adds to methyl vinyl ketone to give [(1RS, 2SR, 5RS,12RS)-5,12-epoxy-1,2,3,4,5,12-hexahydro-7-methoxy-1-(2-nitrophenyl)sulfenyl-2-naphthacenyl]methyl ketone (16) with high regio- and stereoselectivity. The acid-catalyzed 7-oxanorbornadiene→phenol rearrangement of 16 is regioselective and gives (5-acetoxy-3,4-dihydro-7-methoxy-2-naphthacenyl) methyl ketone (20) which was transformed into (±)-7,11-dideoxydaunomycinone ((±)-24), a known precursor of 7.
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  • 90
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    Helvetica Chimica Acta 68 (1985), S. 1079-1088 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The methylene-blue sensitized photooxygenation of heptamethyl Coα,Coβ-dicyanocobyrinate (1, cobester) at ca. -45° and in (D3)acetonitrile solution proceeds readily to the stage of selective double cleavage of the corrin macrocycle. It furnishes the bisected heptamethyl Coα,Coβ-dicyano-5,6:14,15-tetraoxo-5,6:14,15-disecocobyrinate (3) in 91% yield after warming the photooxygenation mixture to room temperature. Complex 3 is also obtained by photooxygenation of the secocorrinoid oxygenation products of 1, namely of heptamethyl Coα,Coβ-dicyano-5,6-dioxo-5,6-secocobyrinate (2a) and of its isomer heptamethyl Coα,Coβ-dicyano-14,15-dioxo-14,15-secocobyrinate (2b). When the raw photooxygenation product of 1 is kept at low temperature, 3 is not formed in a significant amount; spectral analysis reveals 4 as intermediate that is transformed into 3 quantitatively upon warm-up and storage at r.t. Compound 4 is assigned the structure of heptamethyl Coα,Coβ-dicyano-5,6-epidioxy-5,6-dihydro-14,15-dioxo-14,15-secocobyrinate, based on NMR-spectral data and since 4 is also formed cleanly in the corresponding low-temperature photooxygenation of 2b. Catalytic reduction of the Co(III) complex 3 (H2, Pt/C) in the presence of EDTA produces a colourless oil, from which the bicyclic fragments 5 (corresponding to rings A and D of 1) and 6 (corresponding to rings B and C of 1) are obtained in 99 and 91% yield, respectively, after chromatographic separation.
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  • 91
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    Helvetica Chimica Acta 68 (1985), S. 1107-1113 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thermolysis of 5,6-epimino-5,6-dihydro-β-ionone (1) and its N-methyl derivative (2) leads to their monocyclic isomers 6 and 10, respectively, presumably due to a direct [1,5]-H shift; on prolonged heating, these isomers are converted easily into pyrrole derivatives. In contrast, the thermoisomer 12 resulting from 5,6-(N-methoxycarbonyl)epimino-5,6-dihydro-β-ionone (3) by the same mechanism, does not undergo further ring transformation, but equilibrates with its more stable tautomer 13.
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  • 92
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    Helvetica Chimica Acta 68 (1985), S. 1133-1139 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Diels-Alder Reactions with Activated 4-Methyl-1,3-pentadienesEthyl 4-methyl-1,3-pentadienyl ether, trimethyl[(4-methyl-1,3-pentadienyl)oxy]silane, and 1-(4-methyl-1,3-pentadienyl)pyrrolidine and the corresponding piperidine analogue have been used in Diels-Alder reactions with acrylonitrile, ethyl acetylenedicarboxylate, maleic anhydride, and 2,6-dimethyl-p-benzoquinone.
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  • 93
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Derivatives of the unknown 2-amino-6H-1,3-oxazin-6-one 2 have been synthesized for the first time in two steps and in excellent yields, starting from N-cyanocarbonimidates 3a-c and cyanoacetates. The structures of 2a-c are assigned by NMR-spectroscopic methods and corroborated by an X-ray structure analysis of 2c.
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  • 94
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using H-atoms produced in the radiolysis of water vapour, we determined the kinetic isotope effect for the reaction \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm H}^{\rm .} + {\rm RH (R'D)}{\rm H}_{\rm 2} {\rm (HD) + R}^{\rm .} {\rm (R'}^{\rm .}) $$\end{document} where RH and R′D are methylcyclohexane and perdeuterated methylcyclohexane, respectively. The result obtained from the isotope competitive method can be expressed with the Arrhenius-type equation kH/kD = (0.51 ± 0.04) exp[(8.58 ± 0.25) kJ mol-1/RT] over the temperature range from 363 to 483 K. The occurrence of H abstraction from primary, secondary, and tertiary C—H bonds in methylcyclohexane is taken into consideration in the interpretation of the Arrhenius-type expression obtained. Theoretical interpretation of the kinetic isotope effect has been achieved on the basis of the transition-state theory and a semiempirical London-Eyring-Polanyi-Sato potential-energy surface. The tunnel effect is found to play a role in the H-abstraction. Several methods for estimating the tunnel correction factors have been discussed.
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  • 95
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: MNDO and STO-3G calculations rationalize the relative instability of the title propellanes vis-à-vis the title products that are formed exclusively.
    Additional Material: 1 Ill.
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  • 96
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    Helvetica Chimica Acta 68 (1985), S. 1193-1195 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 13C-NMR longitudinal relaxation rates are analysed with the Woessner equations: in CDCl3 solution at room temperature, 1-phenyladamantane has rotational diffusion coefficients R‖ = 8.1 × 1010 rad · s-1 and R⊥ = 1.1 × 1010 rad · s-1 corresponding to high motional anisotropy (σ = 7.4).
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  • 97
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and photolysis of the title compound 3 is described. Irradiation (λ 〉 280 nm, MeCN) of the di-epoxyketone 3 leads predominantly to γ-H abstraction. Cyclization furnishes the cyclobutanols 22-24, while cleavage gives compound 25, presumably via the allene-oxide intermediate 36. Further, products 27 and 28 are formed by Norrish fragmentation and by initial cleavage of the C(α)—O bond of the oxirane, respectively. The structures of the products 22-25, 27, and 28 were assigned on the basis of the spectral data of the photolysis products of the 13C-labelled diepoxyketone[6,6-dimethyl-13C2]-3 and by X-ray analysis of the compounds 24 and 35, the latter being the p-nitrobenzoate of 22.
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  • 98
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 1235-1242 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2-[2-(Alkylimino)-2-phenylethylidene]pyrrolidines (vinamidines, 3-6) were obtained either via activation of the corresponding vinologous amide 1 with Meerwein salt and subsequent treatment of the intermediate 2 with an amine, or more directly by acid-catalyzed condensation of the Schiff bases derived from acetophenone with 2-ethoxy-1-pyrroline. Nitrosation of these vinamidines led to α,α′-diimino-oximes. In two cases (10, 11), these oximes underwent acid-catalyzed rearrangement with formation of a 5,6,7,8-tetrahydroimidazo[1,2-a]pyridine ring system (12, 13). X-Ray analysis of one of these products (13) and also of one of the vinamidine salts (6) are presented.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 99
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The sodium salts of (S)-alanine, (S)-phenylalanine, (S)-valine, and (S)-methionine are condensed with pivalaldehyde to imines 5. Cyclization by treatment with benzoyl chloride in cold CH2Cl2 gives mainly (4:1 to 〉 99:1) the (2S,4S)-4-alkyl-3-benzoyl-2-(tert-butyl)-1,3-oxazolidin-5-ones (6; cis-configuration) in high yields (85-95%). The oxazolidinones 6 and 7 are deprotonated with lithium diethylamide (LDEA) in tetrahydrofuran (THF) and alkylated (Mel, benzyl bromide) or hydroxyalkylated (benzaldehyde) to 4,4-disubstituted oxazolidinones 9 and 10, respectively, with high diastereoselectivity (9:1 to 50:1; relative topicity ul). Hydrolysis of three of the oxazolidinones to amino acids of known configuration and optical purity indicates that little if any racemization occurs in the process.
    Type of Medium: Electronic Resource
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  • 100
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 1276-1282 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A mixture of sponges of the East Pyrenean Mediterranean is shown to contain the known sponge products longifolin (1), avarol ((+)-3), and avarone (4) and the terrestrial-plant product sesquirosefuran (2), besides to the new furano-sesquiterpenoids tavacfuran (= 3-methyl-2-[(3′Z)-3′-methyl-4″-methyl-2″-furyl-3′-butenyl]furan; (5) and tavacpallescensin (= 5,10-dihydro-6,9-dimethyl-4H-benzo[5,6]cyclohepta[1,2-b]furan; 6) and the new furano-butenolide sesquiterpenoids tavacbutenolide-1 (= (±-4-ethoxy-2-methyl-4-)[(2′E)-2′-methyl-4′-(3″-methyl-2″-furyl)-2′-butenyl]-2-buten-4-olide; (±)-7) and tavacbutenolide-2 (= (±)-4-ethoxy-3-methyl-4-[2′E)-3′-methyl-4′-(4″-methyl-2″-furyl)-2′-butenyl]-2-buten-4-olide; (±)-8). Structural assignments are based on NMR data and on the synthesis of the (E)-isomer of 5. The sponge Dysidea tupha of the same area is also shown to contain the two sesquiterpenoids ent-furodysinin ((-)-14), which is enantiomeric to a product of a Dysidea sp. of Australian waters, and tuphabutenolide ((+)-15).
    Type of Medium: Electronic Resource
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