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  • 2000-2004
  • 1980-1984  (668)
  • 1920-1924  (232)
  • 1870-1879
  • 1984  (668)
  • 1921  (232)
  • Organic Chemistry  (878)
  • breast cancer
Material
Years
  • 2000-2004
  • 1980-1984  (668)
  • 1920-1924  (232)
  • 1870-1879
Year
  • 1
    ISSN: 1436-2813
    Keywords: histochemical assay ; breast cancer ; estrogen receptor ; fluorescent estradiol conjugate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Surgical specimens from 60 Japanese women with breast cancer were studied histochemically to detect estrogen receptors (ER). Forty-six were analyzed in a double blind study designed to compare the histochemical method using fluorescent estradiol conjugate for detection of ER (FITC method) with findings in case of the currently employed dextran coated charcoal (DCC method) techniques. The ER test was positive in 39 (65 percent) of the 60 cases studied by FITC method. Of the 46 cases analysed in a double blind study, 41 (89.8 percent) showed the same results. Of the 5 with inconsistent test results, 2 showed positive DCC and negative FITC, and 3, negative DCC and positive FITC. According to the histologic type, the FITC method demonstrated a low positive ER response rate in scirrhous cases (57 per cent), whereas the positive rate was 67 percent among papillotubular-type cases and 65 percent among medullary tubullar-type cases. In relation to menstrual status, the positive rates were 68 percent and 64 percent among premenopausal and postmenopausal women, respectively. However, in relation to tumor size, no difference was noted in the positive response rate by either method. Therefore, both the DCC and FITC methods are clinically useful to determine the indications for hormone therapy.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1436-2813
    Keywords: breast cancer ; recurrent breast cancer ; surgical hormone therapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Left suprarenal-inferior mesenteric venous shunt (Inokuchi) was prescribed for 80 patients with recurrent breast cancer and the efficacy of hormone coditioned cancer chemotherapy was assessed. The patients were separated into 3 groups according to the historical regimen of combined chemotherapy: Group I; surgical hormone therapy alone, Group II; surgery plus short term chemotherapy, and Group III; surgery plus long term chemotherapy. The 5 year survival rate of the responsive patients to the surgical hormone therapy was as high as 84.6 per cent in Group III, as compared to that of Groups I and II, 41.7 per cent and 16.7, respectively. Survival was not prolonged in non-responsive patients, regardless of the group. These findings indicate that surgical hormone therapy combined with postoperative long term cancer chemotherapy is a valid and effective method for treating recurrence of breast cancer.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1436-2813
    Keywords: microscopic carcinoma ; breast cancer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Microscopic cancer is extremely rare even among “occult breast cancers”. We treated a 70 year old woman with complaints of serosanguineous nipple discharge which yielded cytologically Class V cancer cells. Microdochectomy was performed and intraductal carcinoma was verified histologically in serially cut sections. Following a simple mastectomy, she has been well with no evidence of recurrence or metastasis, at this time.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 26 (1984), S. 143-146 
    ISSN: 1432-1041
    Keywords: alkaloids ; breast cancer ; rauwolfia ; antihypertensive drugs ; case control study
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In a case-control study of 1881 women with breast cancer and 1523 controls with benign conditions, 65 cases (3.5%) and 64 controls (4.2%) reported having used a drug that contained rauwolfia, giving a rate ratio estimate of 0.8 (95% confidence interval, 0.5–1.1). Use that ended more than a year previously was negatively associated with breast cancer (rate ratio, 0.5; 95% confidence interval, 0.2–0.9). The risk of breast cancer did not vary significantly according to duration of use. Nor did it vary within strata of varying base-line risk, such as age at first pregnancy. The data suggest that rauwolfia alkaloids do not increase the risk of breast cancer.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-0646
    Keywords: methyl-GAG ; MGBG ; breast cancer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The Southwest Oncology Group has evaluated methyl-GAG on a weekly schedule among patients with metastatic breast cancer. Among 72 fully and partial evaluable patients, one complete and four partial responses were seen. Toxicity was similar to other trials with this compound except for thrombocytopenia which was more frequent and severe and probably related to tumor infiltrating marrow. In addition, one patient experienced recall dermatitis following methyl-GAG. This toxicity has not been previously reported with this compound. Methyl-GAG has minimal activity at this dose and schedule among heavily pretreated patients with breast cancer.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Breast cancer research and treatment 4 (1984), S. 159-168 
    ISSN: 1573-7217
    Keywords: breast cancer ; mastectomy ; post-operative ; radiation therapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In current practice, the management of early stage breast cancer involves a multidisciplinary cooperation among surgeons, radiation therapists, and medical oncologists. The goals of local treatment in this setting are to secure tumor control and to identify patients who are to be treated with adjuvant systemic therapy. For patients treated by mastectomy, the value of post-operative radiotherapy in primary treatment remains controversial. In this review, we examine the evolution of treatment philosophies for operable breast cancer and the results from recent clinical studies in an attempt to assess the current role of post-operative radiotherapy.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Breast cancer research and treatment 4 (1984), S. 221-225 
    ISSN: 1573-7217
    Keywords: breast cancer ; chemotherapy ; response prediction ; thymidine kinase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Cytosols from breast cancers were measured for estrogen receptor (ER) and thymidine kinase (TK) activity. There was no correlation between ER and TK in 137 primary breast cancers studied. The results of TK from 57 metastatic breast cancers were correlated with the response or failure to subsequent hormonal therapy or chemotherapy. TK did not predict the responses to hormonal therapy in 12 patients. Of the 45 patients treated with chemotherapies, 13 of 15 tumors with TK over 80 pmol/mg/min responded (86%), while only 4 of the 30 tumors (13%) with TK below 80 pmol/mg/min responded (p〈0.001). TK appears to be useful in predicting the responses to chemotherapy.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Breast cancer research and treatment 4 (1984), S. 227-232 
    ISSN: 1573-7217
    Keywords: anthropometry ; breast cancer ; cachexia ; fat ; wasting ; muscle wasting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An anthropometric study was undertaken to determine muscle and fat areas in 50 cancer patients and 258 control patients suffering from minor conditions, to assess the degree of cachexia in patients with breast cancer, and in patients with other types of cancer. Patients suffering from cancers other than those of the breast showed muscle and fat wasting when compared with matched standard values and when the muscle and fat area measurements were expressed as a percentage of the appropriate mean standard value. Breast cancer patients showed increased muscle and fat area values, irrespective of whether they were in remission, or had progressive disease. This is interesting in view of the strong association between dietary fat intake and breast cancer incidence, and correlates well with present ideas on nutrition and the incidence of breast cancer.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Breast cancer research and treatment 4 (1984), S. 3-10 
    ISSN: 1573-7217
    Keywords: breast cancer ; natural history ; nodal status ; nuclear grade ; prognostic factors ; sinus histiocytosis ; transition pathways
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This review analyzes the results of 692 breast cancer patients from the Norwegian Radium Hospital. All cases were diagnosed during the period 1951–1959 and the average follow-up time was just under eight years. All patients received a radical mastectomy and had their diagnoses pathologically confirmed by a separate reviewer. The purpose of this paper is to apply a novel method of analysis in order to infer the longitudinal course of the disease as if it had not been interrupted by treatment. The method allows one to estimate the average times between changes in the biological factors which characterize the natural history of the disease. Applying this method to the Norwegian data has resulted in identifying three pathways of the natural history of the disease. The tumor growth rates differ for these pathways and are in the approximate ratio 1:5:27. Furthermore, we can estimate the potential benefit from earlier diagnosis. Two of the three pathways would seem to benefit from earlier detection.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1573-7217
    Keywords: androsterone ; breast cancer ; a-cortolone ; gas chromatography ; urinary steroids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The amounts of urinary androsterone and etiocholanolone are highly correlated with recurrence rates in patients with early breast cancer after treatment by mastectomy. A more efficient means of predicting the clinical course of the disease is obtained by using a ratio of these compounds to the amounts of individual 17-hydroxycorticosteroids in the urine. For instance, the ratio of androsterone to a-cortolone is particularly effective in identifying women with a high rate of recurrence, and this is largely independent of pathological stage and tumor grade.
    Type of Medium: Electronic Resource
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  • 11
    ISSN: 1573-7217
    Keywords: monoclonal antibody ; breast cancer ; estrogen-induced protein ; immunohistochemistry ; secretory protein ; ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We have previously reported the production of monoclonal antibodies which detect, by immunohistochemistry, an estrogen-induced protein of molecular weight 24,000 daltons (24K). This protein, of unknown function, has been detected in: a) estrogen receptor-positive breast cancer cell lines but not in receptornegative lines; b) several human normal estrogen target organs; and c) certain human carcinomas, including breast tumors. To examine the subcellular localization of this 24K estrogen-induced protein, we have done immunohistochemical studies at light and electron microscopic levels using a human breast tumor cell line (MCF-7) grownin vitro and also in nude micein vivo. MCF-7 cells grown in the ascites fluid of nude mice and processed for paraffin sections showed a defined polarity, and the 24K protein was localized in the apical cytoplasm of the cells. After cytocentrifugation, MCF-7 cells grownin vitro displayed 24K protein mainly confined to large cytoplasmic granules. The presence of 24K protein in cytoplasmic granules was also seen by immunoelectronmicroscopy in MCF-7 cells grown bothin vitro andin vivo. The granules had different sizes, shapes, and 24K immunostaining intensity. The morphological evidence suggests that the 24K estrogeninduced protein is secreted from the cells.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Breast cancer research and treatment 4 (1984), S. 189-193 
    ISSN: 1573-7217
    Keywords: estrogen receptor ; breast cancer ; EGF receptor ; growth factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The capacity for specific binding of125I-epidermal growth factor (EGF) was studied in crude membrane fractions from 95 human breast carcinomas. About 42% of the samples showed saturable, high affinity, specific binding of EGF. In 21% of the tumors we were able to demostrate high (above 10 fmoles/mg protein) binding capacity. Moreover, high EGF receptor values were associated with a low content of estradiol receptor. These studies are related to the definition of new biochemical markers in human breast cancer.
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  • 13
    ISSN: 1573-7217
    Keywords: bone scans ; breast cancer ; follow-up ; treatment failure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A considerable fraction of first metastases in breast cancer patients are found in the skeletal system. Consequently, to improve the probability of detecting bone lesions, protocols of the National Surgical Adjuvant Breast and Bowel Project (NSABP) have required radionuclide scans every six months for the first three postoperative years and yearly thereafter. The present study was conducted to evaluate the worth of 7984 bone scans performed prior to documentation of first treatment failure on 2 697 stage II (positive node) patients entered into NSABP clinical trial B-09. At the time of evaluation, there were 779 patients with a treatment failure, 163 (20.9%) of whom had their recurrence limited to bone. At most, 52 (0.6%) of the total number of screening scans were efficacious in detecting lesions in asymptomatic patients. As a result of this minimal benefit from routine scans, it was recommended that they be conducted less frequently. In presently ongoing NSABP studies, asymptomatic patients having tumors with positive axillary nodes receive scans at yearly intervals for the first three years. Future NSABP trials will require follow-up bone scans only as indicated by symptoms.
    Type of Medium: Electronic Resource
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  • 14
    ISSN: 1573-7217
    Keywords: breast cancer ; chemotherapy ; endocrine therapy ; mammography ; physical examintion ; response evaluation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The evaluation of the response of primary breast cancer to systemic therapy is difficult. Evaluable primary lesions may be assessed both by physical and by mammographic examination. In this study, response to therapy was evaluated after 4 cycles of CMF or CMF plus tamoxifen in 49 patients with locally advanced breast cancer entering a prospective randomized trial. In 35 patients response was evaluated by both physical examination and mammography. In some cases there was disagreement between physical examination and mammograhy in quantifying the magnitude of response. In 8 of 35 (22.9%), the overall response was overestimated by physical examination versus mammography, while in 3 of 35 (8.6%) the reverse was true. Taking into consideration different criteria in attributing the overall response, i.e. selecting physical examination only, mammography only, or the most favorable or the least favorable response between the two methods of assessment, the objective remission rates were 65.7%, 54.3%, 71.4% and 45.7%, respectively. The data suggest that both physical examination and mammography should be used in evaluating the response of primary breast cancer to a systemic treatment. Should these two methods yield contrasting results, the data obtained with each method should be reported. The best observed response may be employed in determining the overall response.
    Type of Medium: Electronic Resource
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  • 15
    ISSN: 1573-7217
    Keywords: breast cancer ; estrogen receptors ; menopausal status ; obesity ; risk factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The relation between estrogen receptors (ER) in breast cancer and risk factors was studied in 456 Japanese patients. ER was shown to be positive in 55.3% (252/456) of patients. There was no difference in ER positivity between pre- and postmenopausal patients. In premenopausal patients, only the age at menarche and obesity showed some influence on the ER positivity of breast cancer. Among postmenopausal patients, on the contrary, ER(+) cancers were predominant in the patient groups that have been known to be higher in the risk of incidence of breast cancer. The factors included were the age at marriage, number of pregnancies, number of live children, and body weight. Of these, the body weight of patients was the strongest influence on the ER positivity in the postmenopausal patients. After excluding the effects of body weight, some of the reproductive factors such as number of pregnancies and number of live children were shown to be related to the ER status. These results may suggest the combination of lower incidence of breast cancer and lower percentage of ER(+) cancers in Japanese postmenopausal women as compared with the Western countries.
    Type of Medium: Electronic Resource
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Breast cancer research and treatment 4 (1984), S. 45-48 
    ISSN: 1573-7217
    Keywords: breast cancer ; hormone therapy ; oophorectomy ; premenopause ; tamoxifen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Clinical results of tamoxifen (‘Nolvadex’-ICI) monotherapy in 44 premenopausal women with advanced breast cancer have been reviewed. Objective tumor regression was achieved in 12 (27%) patients and a further 10 (22%) were classified as ‘stabilized’. Median duration of response was 12.7 months at the time of analysis. Greatest benefits occurred in soft tissue dominant and receptor-positive tumors, but there was no correlation between tumor response and other clinical manifestations of estrogen deprivation (e.g. menstrual disturbance, hot flushes). The benefits of conventional doses of tamoxifen do not therefore appear to be influenced by menopausal status and compare favorably to achievements reported after surgical oophorectomy.
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  • 17
    Electronic Resource
    Electronic Resource
    Springer
    Breast cancer research and treatment 4 (1984), S. 69-77 
    ISSN: 1573-7217
    Keywords: breast cancer ; chemotherapy ; clinical trials ; combined chemoendocrine therapy ; immunotherapy ; non-myelosuppressive agents ; prognostic factors ; response rates ; targeting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Over the past twenty years, breast cancer has come to be much more commonly regarded and treated as a systemic disease. Conventional chemotherapy and endocrine therapy used according to schedules that are tolerable to patients are generally effective and often induce worthwhile responses; nevertheless, the responses in general have a median duration of less than a year, and these therapies are rarely if ever curative. Continued efforts to use available agents with mere modifications of schedule and intensity seem unlikely to substantially improve upon the modest success already achieved. Rather, we desperately need radically new schedules, new agents (especially non-myelosuppressive agents), and new approaches (e.g. monoclonal antibody targeting of drugs, toxins, or radionuclides, perhaps combined with tumor sensitizing agents such as heat). It is our hope that consideration of some of these issues will encourage others to be bolder in devising the next generation of clinical trials.
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  • 18
    ISSN: 1573-7217
    Keywords: breast cancer ; immunology ; stage of disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Concepts regarding cell-mediated immunity and breast cancer are reviewed. Patients having in situ breast cancers have been found by in vivo and in vitro measurements to have cell-mediated immunity to autologous and homologous in situ breast cancer tissue which may last for some time after diagnosis. These observations suggest that antigenically similar cancers arising subsequently in the contralateral breast should be less likely to progress beyound the in situ stage and, if they do become invasive, should exhibit prognostically favorable signs of cell-mediated immunity, e.g. sinus histiocytosis in the lymph nodes and/or lymphoid infiltrate and perivenous lymphoid infiltrate associated with the primary tumor. Cell-mediated immunity has also been shown to be negatively associated with stage of disease at diagnosis for invasive cancers, i.e. the proportion of patients exhibiting cell-mediated immunity decreases as the stage at diagnosis increases. These observations suggest that the stages of independent breast cancers occurring in the same woman should be positively correlated. Data from the SEER Program of the National Cancer Institute were examined in this regard and a strong positive association between the stage of first and second independent primary breast cancers was found with the effect on the stage of a second breast cancer following a first invasive breast cancer appearing to decrease with time subsequent to diagnosis. These observations are consistent with the immunogenicity of breast cancer.
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  • 19
    ISSN: 1573-7217
    Keywords: breast cancer ; clinical correlates ; natural killer activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We have determined the natural killer (NK) activity of peripheral blood lymphocytes obtained from 121 women undergoing surgery for primary breast cancer. NK activity was measured using51Cr-labeled K562 target cells and effector: target ratios of 100:1, 50:1 and 10:1. The patients' lymphocytes gave a wide range of values with a mean (± S.E.) cytotoxicity of 22.6% ± 1.3, and a median of 20.9% at the 50:1 effector:target ratio. These results did not differ significantly from the mean and median NK levels obtained with the peripheral blood lymphocytes of normal blood donors (mean = 23.1% ± 1.9, median = 18.8%). Mean NK activity determined at the first postsurgical examination (⩽6 months postoperative) was significantly lower than the mean NK activity at surgery. The most significant decreases were seen in patients undergoing chemotherapy prior to the first follow-up examination. Subsequent tests (〉6mo,⩽12 mo) show a recovery of NK activity to preoperative levels. A negative correlation was seen between NK level and maximum tumor diameter. NK levels also varied with tumor histiotype. No association was seen between NK levels and either the number of involved lymph nodes, pathologic tumor grade, the presence of estrogen or progesterone receptor, or the age, menopausal status or smoking history of the patients. A positive correlation was seen, however, between NK levels and number of pregnancies and live births.
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  • 20
    ISSN: 1573-7217
    Keywords: breast cancer ; Buserelin ; LHRH agonist ; premenopausal women ; tamoxifen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Seventeen premenopausal women with metastatic breast cancer were treated with the potent Luteinizing Hormone Releasing Hormone (LHRH) agonist Buserelin as a first-line agent. Twelve patients (group A) were treated with Buserelin alone and five patients (group B) with the combination of Buserelin and tamoxifen from the start of treatment. In nine patients of group A tamoxifen was added to Buserelin later on because of tumor progression or recurrent peaks of plasma estradiol (E2). Chronic intranasal therapy with Buserelin alone, preceeded by parenteral administration, caused an objective remission in four patients (2 × C.R., 2 × P.R.) and stable disease in four further patients without causing side effects. The longest duration of response until now is more than 29 months. After addition of tamoxifen a partial response occurred in two more patients of group A. Anovulation with suppressed progesterone secretion was reached in all patients treated with Buserelin alone, but transient peaks of E2 occurred in the majority (60%) of the patients. Addition of tamoxifen to Buserelin treatment caused disappearance of E2 peaks in 2 patients, but also reappearance of progesterone secretion with recurring E2 peaks in 3 other patients; in one case hyperstimulation of the ovaries was observed without progression of tumor growth. In group B only one woman showed a complete castration effect, while in four patients progesterone secretion was not (completely) suppressed. In two of these five patients an objective response occurred. In conclusion, Buserelin appears effective in the treatment of premenopausal women with metastatic breast carcinoma, but with the regimen used close control of endocrine parameters is necessary because of the variation in hormonal response with a risk of (hyper)stimulation of the ovaries, especially during combination therapy with tamoxifen.
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  • 21
    ISSN: 1573-7217
    Keywords: breast cancer ; membranes ; prolactin ; receptors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In order to perform measurement of PRL binding and to improve the knowledge of pathophysiological variations in human mammary cancers, we have investigated in detail the binding characteristics of PRL in membranes prepared from these tumors. The optimization of the assay requires the selection of membranous components of light density (〈1.17); the tracer could be either125I-PRL after affinity purification on PRL receptors or125I-hGH without a purification step. It is favorable to utilize a high amount of protein and 200 000 cpm (2 ng) of tracer. Demonstration of the presence of receptors for PRL with a high affinity (Kd = 3 × 10−10 M) in breast cancer is presented. The hormonal specificity of these receptors is studied: only lactogenic hormones (hGH, oPRL, hPRL, and hPL) are able to compete for binding of125I-hPRL whereas bGH or insulin are without effect. Considering the known effect of PRL on cell multiplication, it is tempting to suggest that this hormone could have a crucial role in the development of breast tumor in humans and that therapies which would suppress secretion of PRL and GH could be beneficial.
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  • 22
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 47-53 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The He(Iα) photoelectron (PE) spectra of tris(perfluorocyclobuta)benzene 4(F)3,3,4,4,7,7,8,8,11,11,12,12-Dodecafluorotetracyclo[8.2.0.02,5.06,9]dodeca-1,5,9-triene, tris(perfluorocyclopenta)benzene 5(F)1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9-Octadecafluoro-2,3,4,5,6,7,8,9-octahydro-1H-trindene., tetrakis(perfluorocyclobuta)cyclooctatetraene 6(F)3,3,4,4,7,7,8,8,11,1l,l2,l2,l5,15,16,16-Hexadecafluoropentacyclo[12.2.0.02,5.06,9.010,13]hexadeca-1,5,9,13-tetraene., and of tetrakis(perfluorocyclopenta)cyclooctatetraene 7(F)1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12-Tetracosafluoro-1,2,3,4,5,6,7,8,9,10,11,12-dodeca-hydrotetracyclopenta[a,c,e,g]cyclooctene. are reported. A tentative assignment of the PE spectra is derived by empirical correlation with those of relevant reference compounds. The results suggest that 6(F) retains the D4h-conformation in the gas phase, i.e. A conformation with a planar cyclooctatetraene ring, as observed in the crystal. All four compounds exhibit a sharp increase of their first ionization energies, relative to the corresponding parent hydrocarbons, due to the perfluoro effect.
    Additional Material: 1 Ill.
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  • 23
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ligand 2,11-bis(diphenylphosphinomethyl)benzo[c]phenanthrene (1) has been used to prepare complexes of the type [PtL(1)] (L = C2H4, CH2=CH—CO2Me, PhC≡CPh, MeC≡CMe, MeO2CC≡CCO2Me, (i-Pr)O2CC≡CCO2(i-Pr), Ph3P and CO). It is shown that these complexes are less labile than the corresponding species [PtL(Ph3P)2]. The preparation of complexes trans-[PtX(R)(1)] by oxidative addition of RX (RX = PhCH2Br and Mel) to [Pt(C2H4)(1)] is described. The isolation of [PtO2(CH3)2CO(1)] is also reported.
    Additional Material: 3 Tab.
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  • 24
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The radical anions of the compounds N1N, N3N and N5N, in which two naphthalen π-systems are separated by 1, 3 and 5 spirobonded cyclobutane rings, respectively, and tha tof the reference compound N1, containing one naphthalene π-system and one cyclobutane ring, have been studied by ESR and ENDOR spectroscopy under a variety of experimental conditions. The intramolecular electrons spin transfer between the two π-moieties in N3N.⊖ and N5N.⊖ is slow on the hyperfine time-scale, irrespective of the applied conditions. It is also slow in N1N.⊖, except for media of high solvating power. In such media, with a slight reduction of N1N to its radical anion, a paramagnetic species is observed, the hyperfine data for which are consistent with N1N to its radical anion, a paramagnetic species is observed, the hyperfine data of which are consistent with N1N.⊖, undergoing a fast intramolecular electron spin tansfer. The ESR and ENDOR spectra of this species are superimposed on those characteristic of a slow transfer. It is suggested that the fast and slow transfer involve the syn- and anti-conformations, respectively, since the distance, r, between the two naphthalene π-systems of N1N.⊖ is considerably shorter in the former than in the latter (r = 740 vs. 880 Pm for the distance between the centres of the π-systems). Glassy solutions of exhaustively reduced N1N display signals of the dianion triplet state, whereas no such signals are found for N3N and N5N. The zero-field splitting parameter, D, is 4.7 mT, corresponding to r ≈ 480 pm.
    Additional Material: 5 Ill.
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  • 25
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Loss of CH3., CH4, C2H4, C3H5., C3H6 and C3H7 from the molecular ions of a number of 13C-labeled analogs of 4,4-dimethyl-1-pentene was studied both in normal (source) 70-eV electron impact (EI) spectra dn in metastable spectra. For loss of CH3. in the source, 96% of the methyl comes frm positions of 5, 5′ and 5″, while the remainder comes from position 1. In the metastable spectra, loss of C-1 (16%) and C-3 (9%) is increasing in importance. The loss of ethylene is a particular case: either C-1 or C-3 are lost with any other C-atom from positions 2,5,5′, and 5″ (8 × 10%) in the metastable spectra, the probability for simultaneous loss of C-1 and C-3 being 6%. If C-1 seems to these two positions become completely equivalent in the metastable time range. The T-values (kinetic energy release) for the different positions show small, but statisticaly different values and a small isotope effect. Loss of C3H5 (allylic cleavage) is 100% C-1, C-2 and C-3, i.e., no evidence for skeletal rearrangement is seen. This is also true for loss of C3C6 (McLafferty rearrangement) within the source, but in metastable decay the other positions gain in importance. The neutral fragment C3H7. appears to be the the result of consecutive loss of CH3. and C3H4, rather than a one-step loss of propyl radical or the inverse reactions sequence. No metastable reaction can be seen for this reaction. Decomposition of labeled C6H11+ and C5H10+ secondary ions occurs in an essentially random fashion.
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  • 26
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    Helvetica Chimica Acta 67 (1984), S. 450-454 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Up to now the synthesis of para-substituted phenyl-terpyridine ligands was difficult with respect to the purification of the reaction products. We have found that these compounds can easily be isolated as hydrobromides from acetic acid. Starting from the hydrobromides the purification turned out to be easy. Synthesis of para-substituted Cl-, Br-, H3C-, H2BrC-, HO- 2,6-Bis(2-pyridyl)-4-phenylphyridine is reported.
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  • 27
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    Helvetica Chimica Acta 67 (1984), S. 441-449 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Complexation of Silver(I) by Cyclic TetraminesThe nature of Ag(I)-complexes with 1,4,8,11-tetraazacyclotetradecane (1), 1,5,9,13-tetraazacyclohexadecane (2) 1,5,10,14-tetraazacyclooctadencane (3) and 1,6,11,16-tetraazacycloeicosane (4) is studied. The effect of ring size on disproportionation of the Ag() cation in the presence of ligand is reported. The stability of Ag(I)-complexes with 3 and 4 in aqueous solution is determined by means of potentiometric titration.
    Additional Material: 5 Ill.
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  • 28
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    Helvetica Chimica Acta 67 (1984), S. 625-627 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 29
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    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984) 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 30
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    Helvetica Chimica Acta 67 (1984), S. 625-639 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Radical Ions of Bridged [14] Annulenes. Investigations on the Influence of Frontier Orbitals on Reactivity and BondingThe radical anions and the radical cations derived from trans-15, 16-dimethyl-1, 4:8,11-ethandiyliden[14]annulene (6), trans-15-methyl-1,4:8,11-ethandiyliden[14]annulene (7) and cis-15, 16-propano-1,4:8,11-ethandiyliden[14]annulene (8) are described. The hyperfine data of the radical anions 6, 7 and 8 resemble those of the structurally related radical anions of trans-10b, 10c-dimethyldihydropyrene (4) and trans-10b, 10c-dihydropyrene (5). This finding leads to the conclusion, that the change in the relative arragement of the saturated bridge within the fourteen-membered π-perimeter by passing from 4 (5) to 6 (7, 8) does not in fluence the energetic sequence of the lowest unoccupied molecular orbitals. The behavior of 6 and 7 towards oxidation parallels the photochemical reactivity of 4. The hyperfine coupling constants of the radical cations derived from 6 and 7 indicate that the removal of an electron is accompanied by an isomerization of the molecular framework. The investigation of the electron transfer process gby cyclic voltammetry supports these findings. The radical cations prefer the cyclophane-like structures 6a and 7a, in which the central σ-bond (C(15)-C(16) bond) is broken.
    Additional Material: 7 Ill.
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  • 31
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    Helvetica Chimica Acta 67 (1984), S. 664-668 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The photochemical behaviour of the title compound 1a is compared to that of the non-fluorinated parent ketone 2-methylcyclohexanone (1b). Substitution of the CH3- group on C(2) by a trifluoromethyl group strongly enhances 2H- and RH- reduction product formation in cyclohexane or 2-propanol and oxetane formation in the presence of 2-methylpropene as olefinic component. Under all these conditions 1b exclusively undergoes a-cleavage, a process observed for 1a only in non-reducing solvents as benzene or tert-butyl alcohol.
    Additional Material: 2 Tab.
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  • 32
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Treatment of β-keto-acetals, derived from non-enolisable β-diketones, with sulfonic acids in boiling benzene resuots in a smooth retro-Claisen-type fragmentation. The acetal-C-atom is thereby transformed into a carboxylic ester via a dialkoxycarbenium ion, which is dealkylated by the sulfonate counter-ion. Application of this reaction to the diastereomeric monoacetals 3 and 4, derived from cis-9-methyl-decalin-1,8-dione (1), followed by transesterification with CH3OH, yields optically pure 4-(2′-methyl-3′-oxocyclohexyl)butyrate 9 ((+)-9 from 3, (-)-9 from 4) and the monosulfonate of Meso-2,3-butanediol (-)-13 (Scheme 2). Unexpectedly, this cleavage proceeds as well with monoacetal 26, obtained by acetalization of trans-9-methyl-decalin-1,8-dione (27) with 2,2-dimethyl-1,3-propanediol (Scheme 7). Some attempts, aiming at an isomerization of the cis- and trans-decalin derivatives 3 and 24, or 25 and 26, via the postulated carboxonium intermediate, were not successful.
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  • 33
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    Helvetica Chimica Acta 67 (1984), S. 856-865 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alkylation of bicyclo[3.3.0]octane-2,8-dione (1), which is prepared by a modification of the procedure described in the literature, gives the methyl- and propynyl-derivatives 6 and 7 (Scheme 1). In addition to the method described previously (Scheme 2), 9-methyl-cis-decalin-1,8-dione 9 is obtainable stereoselectively either by cyclization of keto-acid 16, or by aldol cyclization of keto-aldehyde 26 and oxydation of the resulting alcohols 24 and 25 (Scheme 4). The β-keto-alcohols 24 and 25 undergo a base-catalyzed isomerization; the trans-decalin isomers 27 and 28 are not detected in this equilibrium mixture (Schemes 4 and 5)l. Monoreduction of cis-dione 9 gives the endo-alcohol 25, while 27 is the favored product of the reductin of trans-dione 10 (Scheme 4). Optically pure (+)-25 can be prepared from (9S,10R)-monoacetal 29 (Scheme 5).
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  • 34
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new tripeptide (dimer), bis[(L-cysteine-S-acetyl)-L-hemicystinyl(S2 → S2)-D-valine] (6) was synthesized by coupling N-(tert-butoxycarbonyl)-S-carboxymethyl-L-cysteine benzyl ester (1) with S-trityl-L-cysteinyl-D-valine benzyl ester and subsequent removal of the protecting groups. After reduction of the disulfide, the free tripeptide Cys (CH2CO-Cys-D-Val) (Ib) was used as a substrate of isopenicillin-N synthetase in a cell-free conversion to 6-[2-((D-2-amino-2-carboxyethyl)thio)acetamido]penicillanic acid (IIa).
    Additional Material: 3 Ill.
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  • 35
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    Helvetica Chimica Acta 67 (1984), S. 902-905 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of the title compounds is described.
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  • 36
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    Helvetica Chimica Acta 67 (1984), S. 927-927 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 37
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Resolution of racemic cis-3-(2-aminophenylthio)-2-hydroxy-3-(4-methoxyphenyl) propionic acid (2) via the cinchonidine salt 3, and brucine salt 4, isolation of the calcium salts (+)- and (-)-5, as well as their cyclization to enantiomeric 1,5-benzothiazepines (+)- and (-)-1, are described. X-Ray single-crystal analysis reveals (2S, 3S) absolute configuration of (+)-1 on the basis of tentative comparison of CD data with those for the 1,4-benzodiazepine derivative (+)-8 of known absolute configuration.
    Additional Material: 4 Ill.
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  • 38
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    Helvetica Chimica Acta 67 (1984) 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 39
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    Helvetica Chimica Acta 67 (1984), S. 927-933 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis ad Structure of Zinc Complexes of 2-Amino-1-azetinesThe 2-dimethylamino-3,3-dimethyl-1-azetines 7a and 7b have been synthesized in analogy to the procedure reported by Ghosez et al. [1] (Scheme). The crystal structure of 1-benzhydryl-azetidindimethyliminium chloride 5a, a precursor of azetine 7a, has been established by X-ray diffraction analysis. Treatment of azetines 7a and 7b with ZnBr2 in CH2Cl2/MeCN yielded tetrahedral bis (azetine)dibromozinc complexes 8a and 8b, respectively (Scheme 2). The molecular structure of 8a has been determined by X-ray diffraction analysis too.
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  • 40
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    Helvetica Chimica Acta 67 (1984), S. 947-952 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The enantioselective synthesis of (+)- and (-)-cis-2-methyl-4-propyl-1,3-oxathine 8 and 9 form (E)-2-hezen-1-ol (1) as common starting material is described. The two enantiomeric forms exhibit different organoleptic properties.
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  • 41
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    Helvetica Chimica Acta 67 (1984), S. 959-963 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyanothyl-subsituted cylohexyl cyclohexanoates, bi(cyclohexanes) and phenyl cyclohexanes were synthisized. Their mesmorphic behaviour is compared to that of the corresponding cyano derivatives. (Cyanoethyl)cyclohexyl cyclohenxanoates show mesmorphic properties in contrast to the corresponding cyano derivative. Separation of the cyano substituent from the rigid core of an anisotropic aliphatic compound by methylene groups enhances the thermodynamic stability of the mesophase. In aromatic compound, the cyanoethyl group leads to lower clearing points. These phenomena are attributed to teh influence of steric effects on the packing density and to the dependence of the clearing point on molecular association.
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  • 42
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    Helvetica Chimica Acta 67 (1984), S. 1000-1002 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nα-L-Iysine with a 2-carboxy-4, 6-dinitrophenyl (Dncp) haptenic group on the ε-amino function is a potent anaphylactogen in the guinea pig. We prepared Nε -Dncp- Nα-benzoly-L-Iysinamide and Nε-Dncp-Nα-benzoyl-L-lysyl-1-aminopropane where the carboxyl group of Iysine is blocked. Both compounds were non-elections of anaphylaxis.
    Additional Material: 1 Tab.
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  • 43
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    Helvetica Chimica Acta 67 (1984), S. 21-28 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: C45- and C50-Carotenoids. Synthesis of Optically Active Acyclic C15-End GroupsThe optically active C15-end groups (S)-12, (S)-13 and (R)-14 were prepared from the C12-synthon (S)-11 in good chemical and optical yield. These C15-end groups are suitable compounds for the synthesis of optically active C45- and C50-carotenoids.
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  • 44
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the crystal structure of the title compound at 98 K the dimethylamino group has pyramidal geometry. The nitrogenlone pair is not directed towards the triple bond; instead, one N—CH3 bond lies almost in the plane of the disubstituted ring, directed away from the triple bond, while the other N—CH3 bond and the lone pair are directed to opposite sides of the plane, nearer to the acetylene. There is a remarkably short intramolecular contact (2.39 Å) between a methyl H- and an acetylenic C-atom. The Taft σI parameter of the arylethynyl substituent appears to be similar to that of a carboxylic ester, judging from the bond-angle deformation at the ipso-C-atom.
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  • 45
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Heart Glycosides of the Arrow Poison of Lophopetalum toxicum LOHERFrom the cytotoxic and positive inotropic acting bark extract of the Philippinan Lophopetalum toxicum eight heart glycosides have been isolated and their structures have been elucidated mainly by field-desorption-MS- and 1- and 13C-NMR spectroscopy. Besides the known k-Strophanthidin (1), Antiarigenin (6) and β-Antiarin (Antiarigenin-3-β-O-α-L-rhamnoside, 10) the following mono- and diglycosides could be identified: strophanthidin-3-β-O-α-6-desoxy-D-allopyranoside (strophalloside, 2), strophanthidin-3-β-O-β-6-desoxy-D-glucopyranoside (= Strophanthidin chinovoside, 3), strophanthidin-3-β-O[-4Oβ-D-allopyranosyl-β-6-desoxy-D-allopyranoside] (4), strophanthidin-3-β-O-[3-O-β-D-glucopyranosyl-β-6-desoxy-D-talopyranoside] (5), antiarigenin-3-β-O-[3-O-β-D-gulopyranosyl-β-6-desoxy-D-talopyranoside] (7), antiarigenin-3-β-O-[4O-β-D-allopyranosyl-β-6-desoxy-D-allopyranoside] (8), and antiarigenin-3-β-O-β-6-desoxy-D-allopyranoside (antiallosid) (9). The structure of strophanthidinchinovoside (3) could be confirmed by synthesis.
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  • 46
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A recent controversy on the interpretation of the ESR spectrum of ionized oxirane is clarified on the basis of the electronic absorption spectra of ionized tetramethyloxirane and 9,10-octalineoxide. The results favour a ring-opened structure for oxirane molecular cation, resulting from C—C bond cleavage and being iso-π-electronic to allyl radical.
    Additional Material: 3 Ill.
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  • 47
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Acylation of Acetylenes with β,γ-Unsaturated Acid Chlorides, A New Synthesis of 5-Substituted 2-CyclopentenonesThe acylation of acetylenes with α,α-disubstituted, β,γ-unsaturated acid chlorides under Friedel-Crafts-type conditions leads to 5-substituted 2-cyclopentenones. Phenols are formed with β,γ-unsaturated acid chlorides bearing at least one α-H-atom. These transformations are explained by the intramolecular cyclization of the initially formed vinyl cation, which, in the cases of α,α-disubstituted acid chlorides, is followed by ring contraction. The reaction leading to 2-cyclopentenones is applied to the synthesis of some spiro[4.4]nona- and spiro[4.5]deca-2,6-dienones.
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  • 48
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    Helvetica Chimica Acta 67 (1984), S. 113-119 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1-Arylazonaphthalenes with all the potential cyclopalladation sites (one peri- and three ortho-positions) substituted by methyl or ethyl groups react with stoicheiometric or catalytic amounts of sodium tetrachloropalladate(II) to the corresponding 2-arylbenzo[g]indazoles. Possible mechanisms for the catalytic cyclization reaction are proposed.
    Additional Material: 1 Tab.
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  • 49
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1n, π*-Excitation of the γ,δ-epoxy-enone (E)-3 leads exclusively to the conformers (Z)-3A + B. On 1π, π*-excitation of (E)-3, in addition to (Z)-3A + B, products 6-9 arising from a carbene intermediate e are formed. However, products of an isomerization via C(γ), O-bond cleavage of the oxirane were not formed on either mode of excitation. On thermolysis, at 80° the conformer (Z)-3A is transformed into (Z)-3B, which on photolysis returns to (Z)-3A and (E)-3. At 160°, however, (Z)-3B rearranges to the isomers 6, 10 and 11.
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  • 50
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    Helvetica Chimica Acta 67 (1984), S. 866-869 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Selective oxidation of benzylic methylene groups through UV irradiation in acetone/water/FeCl3 mixtures is reported. This method applied to a series of model compounds, provides an easy access to the corresponding 1-oxo derivative. Thus, tetralin gives a 100% yield of 1-tetralone, indane leads to 60% of 1-indanone, and diphenylmethane is oxidized to benzophenone with 80% yield. However, under the same conditions, alkyl-substituted aromatic hydrocarbons such as toluene, ethyl- and propylbenzene lead to low yields of aldehydes or ketones. Isochromane furnishes a mixture of two substances which can be interconverted, namely the expected l-isochromanone (9%) and the corresponding hydroxy acid (23%). We failed to apply the method to nitrogen heterocycles containing benzylic groups such as 1,2,3,4- and 5,6,7,8-tetrahydroquinoline as they do not react due to the formation of complexes which precipitate from the solutions.
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  • 51
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pure pencillin N α-sulfoxide (1) and penicillin N β-sulfoxide (2) were obtained by HPLC and tested as substrates for deacetoxycephalosporin C synthetase (DXCS). Neither one of the sulfoxides was utilized under conditions of conversion of penicillin N (8) to deacetoxycephalosporin C (9). The cephalosporin C α and β-sulfoxides (3 and 4, resp.) were also prepared. Relative stabilities of the sulfoxides 3 and 4 are discussed by interpretation of the 13C-NMR spectra.
    Additional Material: 9 Ill.
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  • 52
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Business C,D,E,F,G,H,J,K,L und M, Ten New Tetranortriterpenes from Entandrophragma Bussei HarmsTen new tetranortriterpenes, busseins C, D, E, F, G., H, J, K, L and M have been isolated from the petroleum ether extract of the timber of Entandrophragma bussei Harms. utilizing separation by high-pressure liquid chromatography (HPLC). The structural assignments are based mainly on spectral evidence. For the 1H-NMR spectroscopy extensive use of nuclear Overhauser effects (NOE) was made.
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  • 53
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    Helvetica Chimica Acta 67 (1984), S. 928-930 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 54
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alcohols and phenols are efficiently nitrated with thionyl chloride nitrate or thionyl nitrate, even in the presence of an aromatic moiety. While thionyl chloride nitrate is suitable for nitration of primary OH-groups in carbohydrates, thionyl nitrate is reactive enough to react with secondary OH-groups as well. These reagents permit the highly selective nitration of the 5′-,2′5′- and 3′, 5′-OH-groups of ribonucleosides to produce either mono-or diprotected nitro derivatives in high yields. Carbon acids and the enol form of some ketones are efficiently nitrated with trifluoromethanesulfonyl nitrate/potassium tert-butoxide. Lutidine N-oxide (2,6-(CH3)2C5H3N O) was found to have a marked effect on nitration reactions. Similarly, thionyl chloride nitrite and thionyl nitrite exhibit an excellent capacity for nitrosation of the aforementioned substrates.
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  • 55
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    Helvetica Chimica Acta 67 (1984), S. 934-938 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The radical cations and the radical of 1,2-bis(phenalen-1-ylidene)ethane (1), 1,2-bis(phenalen-1-ylidene)ethene (2) and pentaleno[1,2,3-cd: 4,5,6-c′ d′]diphenalene (3) have been characterized by ESR and ENDOR spectroscopy. The ease of formation of these radical ions and their π-spin distributions are interpreted in terms of a simple model correlates the frontier orbitals of 1, 2 and 3 with the nonbonding MO's of two phenalenyl π-systems.
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  • 56
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    Helvetica Chimica Acta 67 (1984), S. 939-946 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of 1-(2-propynyl)pyridinium salts 3 described. Compounds 3 react with a second pyridine molecule, in the presence of the corresponding hydrochloride, to form products of type 4, Certain bases cause the 1-(2-propynyl)pyridinium salts 3 to rearrange into 1-propadienylpyridinium salts. 5. Diethylamine converts compounds 3 into 1-acetonylpyridinium salts 8. Moreover, treatment of 3 or 5 with sodium methoxide gives enol ether sof type 9, which can be hydrolyzed to teh ketones 8. Addition of bromine to some of teh unsaturated compounds is also reported.
    Additional Material: 5 Tab.
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  • 57
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    Helvetica Chimica Acta 67 (1984), S. 953-958 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: IR-spectroscopic investigations of light-induced rearrangement reactions of nitrosooxymethane (CH3ONO3), nitrosooxyethane (CH3CH2ONO) and N,N-dimethylnitrosamine ((CH3)2NNO) in low-temperature rare-gas matrices have established that these molecules are transformed in two photolysis steps to the previously unknown C-nitroso compounds nitrosomethanol (CH2(OH)(NO)), 1-nitrosoethanol (CH3CH(OH)(NO)), and methyl(nitrosomethyl)amine CH2(NO)(NH)(CH3). Evidence for a similar rearrangement reaction has been advanced for N-Nitrosopyrrolidine which is converted to C-nitrosopyrrolidine . The matrix-isolation technique in combination with wavelength-selective irradiation allowed to trap and characterize an intermediate of rearrangement which revealed to be nitroxyl (HNO) complex (CH2…HNO, CH3CHO…HNO, CH3N = CH2…HNO, and ). Since these findings have a close resemblance with rearrangement reactions of more complex nitrosooxy compounds, nitrosamines, or nitrosohydrazines used in organic synthesis, it is suggested that also in these reactions nitroxyl is present as an intermediate species.
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  • 58
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    Helvetica Chimica Acta 67 (1984), S. 964-967 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,2-Epoxycarotenoids: Isolation of 1,2-Epoxy-1,2-dihydrolycopene from TomatoesThe optically active, 1,2-epoxy-1,2-dihydrolycopene was isolated from tomatoes. Its constitution was established by comparison with the racemic synthetic compound.
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  • 59
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,2-Epoxycarotenoids: Synthesis, 1H-NMR and CD Studies of (S)-1,2-Epoxy-1,2-dihydrolycopene and (S)-1′,2′-Epoxy-1′, 2′ -dihydro-γ-caroteneThe synthesis of (S)-1,2-epoxy-1,2-dihydrolycopene ((S)-1) and (S)-1′, 2′ -epoxy- 1′, 2′ -dihydro-γ-carotene ((S)-2) are described. The CD spectra of the (all-E)-isomers and of the isomers (7Z, S)-1 and (7′Z, S)-2 are discussed. The comparison of the CD spectra of the synthetic (S)-1 and the compound isolated from the tomatoes proves the (S)-configuration of the natural product.
    Additional Material: 9 Ill.
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  • 60
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    Helvetica Chimica Acta 67 (1984), S. 1003-1011 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Plectranthons A, B, C, and D. Diterpenoid Phenanthrene-1,4-diones from Leaf-glands a Plectranthus sp. (Labiatae)The following structures of four new 1,4-phenanthraquionones, isolated in minute amounts from the coloured leaf-glands of a Plectranthus sp. obtained from the borders of Lake Kiwu2, Rwanda, are proposed: plectranthon A (1; 3-hydroxy-5, 7,8-trimethyl-2-(2-propenyl)phenanthrene-1, 4-dione), plectranthon B (2; 2-(2ξ-acetoxypropyl)-3-hydroxy-5,7,8-trimethylphenanthrene-1,4-dione), plextranthon C (3; 3-hydroxy- 7,8-diemethyl-2-(2-propenyl)phenanthrene-1,4-dione), and plectranthon D (4; 3-hydroxy-7,8,10-trimethyl-2-(2-propenyl)phenanthrene-1,4-dione). 2-(2ξ-Hydroxypropyl)-3,6-dihydroxy-5,7,8-trimethylphenanthrene-1,4-dione (11), a compound very similar to 1-4, was prepared by a Wagner-Meerwein, rearrangement of coleon E (5). Biogenetically, the plectranthons are derived from abietanoic precursors. The compounds 1, 2 and 4 are the first natural C20-phenanthrenes of diterpenoid origin.
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  • 61
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Oxidative hydroboration of exo- (1) and end-Fe(CO)3 (2) complexes of 5,6-dimethylidenebicyclo[2.2.2]oct-2-ene are highly stereoselective and give endo -alcohol 3 and exo -alcohol 4 as major products, respectively, Collins oxidations of 3 and 4 furnish the corresponding exo -Fe(CO)3 -complexed 5,6-dimethylidene-2-bicyclo-[2.2.2]octanone 7 and 8. NaBH4 reduction of exo-complexes 7 gives a mixture of 3 and isomeric exo-alcohol 18, whereas reduction of endo-complexes 8 gives the endo-alcohol, endo-complexes 19, as the sole product. The base-catalyzed H/D exchange of 7 and 8 afford the dideuterated exo-complex 35 and the monodeuterated endo-complex 32, respectively. Oxidative hydroborations of the exo-(9) and endo-Fe(CO)3 (10) complexes of 5,6-dimethylidenebicyclo[2.2.1]hept-2-ene give the corresponding exo-alcohols 39 and 40. Oxidation of 39 and 40 gives the exo- and endo-complexes 41 and 42, respectively, of 5,6-dimethylidene-2-bicyclo[2.2.]heptanone. Only Hexo —C(3) can be exchanged in 42, wheres both H-atoms at C(3) in 41 are exchangeable. The endo-Fe(CO)3 group in 8 and 42 blocks the base-catalyzed H/D exchange of Hendo —C(3), thus providing a test for the configuration of Fe(CO)3 group in these systems. These studies have led to a revision of the iron configurations proposed by Hansen et al, [2] for 1, 2, 9 and 10.
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  • 62
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    Helvetica Chimica Acta 67 (1984), S. 361-364 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 63
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Solvolysis rate constants in MeOH and t-BuOh are compared for β-methyl and β-phenyl derivatives of two cycloakyl systems. It appears that the β-phenyl derivatives solvolyse at te same rate as the β-methyl ones. The lack of deceleration is attributed to phenyl assistance. It is established by configurational analysis of the reaction products, that those products which necessarily originate from a cationic species are the most abundant ones. It is suggested that these reactions could proceed through ion-pair intermediates, which are nucleophilically solvated by phelyl or by the solvent. A parallel between phenyl assistance and ‘SN2 (intermediate)’ mechanism, suggested by Bentely & Schleyer, is drawn.
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  • 64
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    Helvetica Chimica Acta 67 (1984), S. 361-372 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The temperature dependence of the water self-diffusion coefficients (D), as well as those of low- and high-field (stationary and time-dependent) specific conductivities (K), have been determined in the percolation regime of ternary mixtures of water, AOT, and oil. For the first time a pronounced similarity in the behavior of D and κ was detected giving instructive hints about the large variations in the specific conductivities of these systems. Results from kinetic and stationary experiments are consistent with a network-structure model of micro phases in the percolation regime in which the micro phases retain their discrete character.
    Additional Material: 8 Ill.
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  • 65
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Facile synthesis of derivatives of 2,4-diphenyl-3-azabicyclo[3.3.1]nonane and 7,9-diphenyl-8-azabicyclo[4.3.1]decaneThe facile synthesis of hydantoins, cyanhydrins and aminonitriles derived from 2,4-diphenyl-3-azabicyclo[3.3.1]nonanone and 7,9-diphenyl-8-azabicyclo[4.3.1]decanone is described. Configurations at C(9) or C(10) of the new compounds wth pharmaceutical and synthetical utility is deduced from their spectral properties.
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  • 66
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    Helvetica Chimica Acta 67 (1984), S. 1328-1347 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of the D-arabino- and D-ribo-ortholactones 13a-f and 15b-f and their treatment with Zn leading to the unsaturated esters 14a-d and 16a-d are described. Possible fragmentation mechanisms are discussed. The results were only compatible wit a concerted, nonsynchronous process, where both the axial lone pair of the ring oxygen atom and the lone pair formed during rupture of the C(5), O-bond participate in the elimination of the axial and of the equatorial C(1)-alkoxy groups, respectively.
    Additional Material: 4 Tab.
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  • 67
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    Helvetica Chimica Acta 67 (1984), S. 1368-1373 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This communication reports ESR-spectroscopic investigations of the radical anion of 1,8-dimethyl[14]annulene (1) which possesses a flexible molecular framework allowing configurational and conformational mobility. The ESR and ENDOR spectra indicate that at higher temperatures (T 〉 160 K), \documentclass{article}\pagestyle{empty}\begin{document}$ 1^{- \atop \dot{}} $\end{document} exists as a mixture of several distinct isomers. One of them, the sole product at T 〈 160 K, is found to be energetically preferred. The configuration and the conformation of this species can be determined by interpretation of the hyperfine data in terms of a singly occupied MO of the 14-membered π-perimeter.
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  • 68
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    Helvetica Chimica Acta 67 (1984), S. 1386-1396 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2-(tert-Butyl)-3,7-dehydrotropone (7-(tert-butyl)bicyclo[3.2.0]hepta-1(7),2,4-trien-6-one; 1) was found to dimerize reversibly to 2A by [2 + 4]-cycloaddition/cycloreversion reaction. The equilibrium lies on the side of the highly strained dimer 2A in the solid state, and on the side of the monomer 1 in solution. The [2 + 4]-reaction is fully perisite-, regio- and stereoselective. Above room temperature, 1 irreversibly formed a decarbonylated dimer 6, probably via the intermediate 9A or 9B, which resulted either from a dimerisation of 1 by [4 + 6]-cycloaddition or from a sigmatropic rearrangement of the originally formed dimer 2A or 2B. Similary, the 6-bromo derivative 14 afforded the corresponding decarbonylated dimer 15. Should the formation of 6 and 15 be due to a primary cycloaddition then that reaction is fully peri-, site- and regioselective. Mild LiAlH4-reduction of 6 and subsequent acetylation yielded the acetate 11, the structure of which was established by an X-ray analysis. More vigorous LiAlH4-treatment also reduced the terminal fulvenoid double bond of 6 and acetylation of the crude product led to the acetated 12 and 13.
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  • 69
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    Helvetica Chimica Acta 67 (1984), S. 1427-1428 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 70
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    Helvetica Chimica Acta 67 (1984), S. 1427-1438 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electromotive Behaviour of Liquid-membrane Electrode Assemblies Based on Enantiomer-selective Chiral IonophoresA comprehensive theoretical treatment is given for the potentiometric behavior of enantiomer-selective membrane electrodes based on chiral ionophores and plasticizers. The membrane model allows for free and complexed enantiomeric or racemic ions (e.g. ephedronium and l-phenylethylammonium ions) as well as for achiral interfering ions. Experiments are derived for the determination of the stoichiometry and the relative stability of enantiomeric ion/enantiomeric ligand complexes, and for the analytical measurement of the enantiomeric excess of ions in solution.
    Additional Material: 5 Ill.
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  • 71
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Water exchange of square-planar Pd(H2O)24+ has been studied as a function of temperature (240 to 345 K) and pressure (0.1 to 260 MPa, at 324 K) by measuring the 17/O-FT-NMR line-widths of the resonance from coordinated water at 27.11 and 48.78 MHz. The following exchange parameters were obtained: k298ex = (560 ± 40) s-1, ΔH* = (49.5 ± 1.9) kJ mol-1, ΔS* = - (26 ± 6) J K-1 mol-1 and ΔV* = - (2.2 ± 0.2) cm3 mol-1. The values refere to an aqueous perchlorate medium with an ionic strength between 2.0 and 2.6 m and a perchloric-acid concentration between 0.8 and 1.7 m, and are interpreted in terms of an associative (a) activation for the exchange. The exchange rate for Pd(H2O)24+ is 1.4 × 106 times faster than for Pt(H2O)24+ at 298 K. A comparison with reactions between other nucleophiles and Pd(H2O)24+ is also made.
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  • 72
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Studies of Organometallic Compounds, XX. Selectivity of 1,4-Addition of Benzyltitanium Compounds with BenzylildenacetoneTetrabenzyltitanium and dialkoxydibenzyltitanium compounds give essentially 1,4- addition with trans-4-phenyl-3-buten-2-one.
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  • 73
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Aminative Reductive Coupling of Aromatic Aldehydes to N,N,N′,N′-Tetraalkyl-1,2-diarylethylenediamines, Induced by Tris(dialkylamino)methylvanadium (IV)In a novel type of reaction, certain aromatic aldehydes (benzaldehyde, p-methoxybenzaldehyde, 1-naphthaldehyde, furan-2-carbaldehyde) and secondary amines are coupled to give N,N,N′,N′-tetraalkyl-1,2-diarylethylenediamines 1-6. The reagents are tris(dialkylamino)methylvanadium(IV) compounds (cf. Eqn. 2). These are generated in situ either from isolable chlorotris(dialkylamino) vanadium(IV) (Eqn. 3), or preferably, from an Et2O/pentane solution of VCl4 which is treated sequentially with 3 equiv. of lithium dialkylamide, 1 equiv. of MeLi, and 0.8 equiv. of an aromatic aldehyde, to give the products 1-6 in a one-pot preparation (Scheme 2). The yields range from 14 to 54%. The diastereoisomeric mixtures (meso- and (±)-forms) obtained are separated by chromatography (Al2O3, petroleum ether/Et2O/Et3N), and the pure stereoisomers fully characterized. A mechanism of the reductive coupling induced by CH3V (NR2)3 is proposed (Scheme 1).
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  • 74
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    Helvetica Chimica Acta 67 (1984), S. 1506-1514 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several oxidative, reductive and C,C-cleavage reactions were performed starting from the three bicyclo[4.2.1]nona-3,7-diene-2-one derivatives 1, 5 and 18. The oxidations were selective and led to the diols 2,8 and 9, and the epoxides 6,9, and 20. The reductions were selective only in the case of 20 21; otherwise they led to mixtures of the alcohols 10 and 11, and of the dienes 14 and 15. The periodate ring cleavages afforded the functionalized cycloheptane derivatives 3, 12, 13 and 16. Configurational assignments were made on the basis of detailed 1H-NMR and X-ray analysis of 20.
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  • 75
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    Helvetica Chimica Acta 67 (1984), S. 1531-1534 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Red-Coloured Abietanoids from Leaf-Glands of Plectranthus strigosus BENTH.Chromatographic examination of the red-coloured diterpenoids from the South-African title plant yielded the following compounds: parviflorone A(1), parviflorone B (2), parviflorone C(3), parviflorone E (4) parviflorone D (5), parviflorone F (6), parviflorone G (7), and parviflorone H (8). Compounds 7 and 8 represent new variants of these quinone methides.
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  • 76
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polar Diterpenoids from Leaf-Glands of Plectranthus argentatus S. T. BLAKEFrom the red leaf-glands of the Australian Plectranthus argentatus the following novel diterpenoids were isolated: coleon-U-quinone (1), 8α,9α-epoxycoleon-U-quinone (3), 6β-formyloxy-7α-hydroxyroyleanone (7), and 5,6-dihydrocoleon U (10), besides the already known compounds 6β, 7α-dihydroxyroyleanone (4), 7α-acetoxy-6β-hydroxyroyleanone (5), and 7α-formyloxy-6β-hydroxyroyleanone (6). Epoxydation of 1 by perborate led in 32% yield to the epoxyquinone 3.
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  • 77
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    Helvetica Chimica Acta 67 (1984), S. 1568-1571 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Partially protected 4- or 5-hydroxy-sugar oximes were transformed into 5- or 6-membered 1-C-nitroglycosyl chlorides, respectively, by reaction with NaOCl under phase-transfer conditions. With the exception of the oxidation of the gluco-derivative 1 giving the anomers 6 and 7, the reactions were completely diastereoselective.
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  • 78
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    Helvetica Chimica Acta 67 (1984), S. 1572-1579 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and the liquid-crystal temperatures of sixty 4-cyano-2-fluorophenyl and 4-cyano-3-fluorophylen 4-substituted benzoates are described. The nematic-isotropic liquid transition temperatures of the most of these novel esters are only marginally lower than those of the corresponding esters containing an H-atom in place of the F-substituent. In several instances, the clearing points of the F-substiuted-phenyl esters are higher than those of the non-substituted-phenyl esters. The nematic ranges of several of the new esters are markedly broader than those of the analogous non-F-substituted-phenyl esters.
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  • 79
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    Helvetica Chimica Acta 67 (1984), S. 1588-1592 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1H-NMR and vapor-pressure osmometry results are presented, which indicate the occurrence of a rapid equilibrium involving the head-to-head dimerization of β44-helices in chloroform solutions of HCO-L-Ile-(D-AIle-L-Ile)4-OMe. This equilibrium typifies the one that, in Urry's view, would be responsible for the formation and breaking down of the ion-conducting channels formed by gramicidin A in lipid bilayers.
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  • 80
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and liquid-crystal transition temperatures of forty ester derivatives of 2-fluoro-4-hydroxybenzonitrile and 3-fluoro-4-hydroxybenzonitrile are reported. The esters contain the trans-1,4-disubstituted cyclohexane or the 1,4-disubstituted bicyclo[2.2.2]octane rings (some contain an additional phenyl ring). Many of the novel F-substituted esters exhibit substantially higher nematic-isotropic transition temperatures than the corresponding unsubstituted esters. The order of clearing points of these laterally substiuted esters differing only in the presence of a benzene ring and the above-mentioned rings id established.
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  • 81
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    Helvetica Chimica Acta 67 (1984), S. 1598-1602 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of New Morphine Partial Structure 15,16-SecomorphinanThe synthesis of a new morphine partial structure, 15,16-secomorphinan, is described. One of the series, (±)-15, 16-secocyclorphan (5), has the analgesic potency of morphine and exhibits good binding to the opiate receptor.
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  • 82
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Diastereoselective Synthesis of Novel Mannich (Bases1) through Titanium ReagentsTrichlorotitanium dialkylamino-alkoxides (2; titanates of N, O-hemiacetals) are generated either from the corresponding lithium alkoxides and titanium tetrachloride (Scheme 1) or by addition of trichloro-dialkuylamino-titanium to aldehydes. The electrophilic (dialkylamino) alkylating reagents 2 are used to convert lithium enolates to β-dialkylamino-ketones and -esters 5 (Mannich bases), see Scheme 2 and Table. One diastereoisomer of the products 5g-5p thus obtained with cyclohexenolate is formed preferentially (66-84%). The configuration of the products of this first diastereoselective version of the Mannich reaction could not yet be determined. A typical procedure for carrying out the reaction is given.
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  • 83
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    Helvetica Chimica Acta 67 (1984), S. 1612-1615 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new, practical method for the optical resolution of bicyclic ketones if illusttrated by the preparation of (+)-(1R,4R)-7-oxabicyclo[2.2.1]bept-5-en-2-one ((+)-1) and (+)-(1R, 2S,4R)-2-cyano-7-oxabicyclo[2.2.1]hept-5-en-2-yul acetate ((+)-4). It involves the diastereoselective formation of a brucine complex with the corresponding cyanhydrine mixture.
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  • 84
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of three-coordinate bis(dialkylphosphinomethyl)benzo[c]phenanthrene Ag(I) complexes, alkyl= t-Bu, (1b), and cyclohexyl, (1c), anion = BF4, CIO4, CIO4, NO3, Cl, Br, I, have been prepared and thier 31P-NMR characteristics recorded. The solid state structures of [Ag(1b)Br], [Ag(1b)Cl] and [Ag(1b)CIO4] have been determined by X-ray diffraction. The Ag atom in these complexes shows distorted trigonal geometry. Selected bond lengths and angles are as follows: Ag-P = 2.463(4) Å and 2.433(5) Å, P-Ag-P=141.6(2)° in the bromo complex, Ag-P = 2.457(2) Å and 2.427(2) Å, P-Ag-P = 142.6(1)° ion the chloro complex, and Ag-P = 2.394(2) and 2.393 (2) Å, P-AG-P = 161.5(1)° in the perchlorato complex.
    Additional Material: 2 Ill.
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  • 85
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    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1625-1629 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two new syntheses of verrucarinic acid (2S, 3R-dihydroxy-3-methylpentanoic acid) and its derivatives, suitably protected for the further conversion to macrocyclic trichothecenes, are described. The first one makes use of a diastereoselective alkylation of a (-)-(S)-malic acid ester and the regioselective reductin of one carboxyl function toa methyl group. The second approach involves a stereoselective addition of an allylsilane to a chiral glyoxylate.
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  • 86
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Control of the Catalytic Synthesis of Pyridine from Alkynes and Nitriles by the (η6-Borinato)-Nigands at Cobaltη6-Borinato groups as ligands at cobalt have unique effects on the chemo- and negioselectivity of the catalytic co-cyclization of alkynes and nitriles. The turnover number of the conversion of acrylonitrile and acetylene to give 2-vinylpyridine is considerably enhanced. Cyano compounds wih polar substitutents such as amino or thio groups can also be reacted. The homogeneous reaction of HCN with acetylene giving pyridine has been achieved for the first time.
    Additional Material: 1 Ill.
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  • 87
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The endocyclic double bond C(2), C(3) in 5,6-dimethylidene-7-oxabicyclo[2.2.1]-hept-2-ene (1) can he coordinated selectively on its exo-face before complexation of the exocyclic s-cis-butadiene moiety. Irradiation of Ru3(CO)12 or Os3(CO)12 in the presence of 1 gave tetracarbonyl [(1R,2R, 3S,4S)-2,3-η-(5,6-dimethylidene-7-oxabicyclo[2.2.1]-hept-2-ene)]ruthenium (6) or -osmium (8). Similarly, irradiation of Cr(CO)6 or W(CO)6 in the presence of 1 gave pentacarbonyl[(1R, 2R, 3S,4S)-2,3-η-(5,6-dimethylidene-7-oxabicyclo[2.2.1]hept-2-ene)]chromium (10) or -tungsten (11). Irradiation of complexes 6 and 11 in the presence of 1 led to further CO substitution giving bed-tricarbonyl-ae-bis[(1R,2R,3S,4S)-2,3-η-(5,6-dimethylidene-7-oxabicyclo[2.2.1]hept-2-ene)]ruthenium (7) and trans-tetracarbonyl[(1R,2R,3S,4S)-2,3-η-(5,6-dimethylidene-7-oxabicyclo-[2.2.1]hept-2-ene)]tungsten (12), respectively. The diosmacyclobutane derivative cis-m̈-[(1R,3R,3S,4S)-(5,6-dimethylidene-7-oxabicyclo[2.2.1]hepta-2,3-diyl)]bis(tetracarbonyl-osmium) (Os-Os) (9) wa also obtained. The Diels-Alder reactivity of the exocyclic s-cis-butadiene moiety in complexs 7 and 8 was found to be significantly higher than that of the free triene 1.
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  • 88
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The products generated by heating 5,6-dimethylidene-7-oxabicyclo[2.2.1]hept-2-ene (1) with Fe2(CO)9, Ru3(CO)12, Os3(CO)12, Cr(CO)3(MeCN)3, (or W(CO)5(MeCN) or by treatment with Fe-atoms have been characterized by spectroscopic methods. Apart from the expected η2- and η4-complexes of the triene 1, condensation products are formed which arise from the formal [4 + 2]-cyclodimerization of 1 involving the endocyclic double bond of one molecule and the diene moiety of a second. The [4 + 2]-cyclodimerization is catalyzed by Os3(CO)12 in MeOH and gives 1,4-epoxy-7-methoxy-2,3-dimethylidene-1,2,3,4,4a,9,9a,10-octahydroanthracene (15)). Fe-Atoms induce a stereoselective [2 + 2]-cyclodimerization pf 1 which involves its endocyclic double bond and produces the dimer 8.
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  • 89
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    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1647-1649 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of 2,3-Unsubstituted N-Acylindoles by [3,3]-Rearrangement of the N-Phenyl-O-vinylhydroxylamine DerivativesSummary, Treatment of N-phenylhydroxamic acids with vinylacetate in the presence of Li2PdCl4 affords 2,3-unsubstituted N-acylindoles via hetero-Cope-rearrangement of the intermediate N-O-vinylhydroxylamine derivatives.
    Additional Material: 1 Tab.
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  • 90
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    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1669-1669 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 91
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    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984) 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 92
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Irradiation of (RS,SR)-3-Phenyl-6-hepten-2-ol (3n) gave the photoproducts 6n-10n. Some reactions of 6n and 8n are reported. The regio- and diastereoselectivity observed in the photoreaction of substituted 5-phenylpentenes is discussed with respect to conformational preferences of the compounds to be irradiated.
    Additional Material: 1 Tab.
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  • 93
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new convenient synthesis of dihydrolysergic acid is described, which allows the preparation of substituted derivatives, especially those with different substitutents in the aromatic ring. Starting from appropriately substituted 5-nitro-2-tetralones, the synthesis leads via a tricyclic isonitrile to the indole-ring closure as the last step, thus circumventing the troublesome protection/deprotection of the latter.
    Additional Material: 1 Tab.
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  • 94
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The portions of the N3H3 singlet potential energy surface corresponding to triaziridines (1), azimines (2) and triazenes (3) have been calculated by ab initio SCF using 3-21G, 6-31G, and 6-31G** basis sets. Minima and transition states were located by force gradient geometry optimization. The most important computation results are: (1) Triaziridines (1): The configuration at the 3 N-atoms is pyramidal. There are 2 stereoisomers, 1a and 1b. The c,t-isomer 1a has less energy than the c,c-isomer 1b. The 2 stereoisomerizations by N-inversion hve rather high activation energies. The N,N bonds in 1 are longer and weaker (STO-3G estimation) than in hydrazine. The N-homocycle 1 exhibits less ring strain than the C-homocycle cyclopropane or three-membered heterocycles. (2) Azimine (2): All 6 Atoms are in the same plane. There are 3 stereoisomers, 2a, 2b, and 2c. The order of ground state energies is (Z,Z) 〈 (E,Z) ≫ (E,E). The 2 N,N bond lengths correspond to multiplicity 1½. The electronic structure of 2 corresponds to a 1,3-dipole with almost equal delocalization of the 4 π-electrons over all 3 N-atoms. The negative net charge at the central N-atom is much less than that at the terminal N-atoms. Azimines should behave as π-donors in complexation with transition metals (3) Triazene (3): All 6 atoms are in the same plane. There are 2 stereoisomers, 3a and 3b. The order of ground-state energies is (E) 〈 (Z). The stereoisomerization proceeds as pure N-inversion. N-Inversion has a high energy barrier inversion at N(1) is faster than at N(2). One of the N,N bond lengths is typical for a double, the other for a single bond. The electronic structure of triazene 3 entails rather localized π- and p-electron pairs at N(1),N(2) and at N(3). Triazenes should behave as p-donors in complexation with transition metals. (4) -N3H3-Isomers: The order of ground-state energies is 3 〈 2 〈 1. The energy differences between these constitutional isomers are much larger than between the stereoisomers of each. The [1,2]-H shifts for conversions of 2 to 3 and the [1,3]-H shift for tautomerization of 3 have relatively high activation energies; both shifts can be excluded as modes of thermal, unimolecular transformations.
    Additional Material: 2 Ill.
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  • 95
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    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1952-1956 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of 4-hydroperoxy-2,4,6-trimethylcyclohexa-2,5-dienone with acetaldehyde using trimethylsilyl trifluoromethanesulfonate as catalyst gives 1,1′-bis[(1,3,5-trimethyl-4-oxo-2,5-cyclohexadienyl) peroxy]diethyl ether (7) in 70% yield. The structure of this unusual acetal was determined by X-ray analysis.
    Additional Material: 1 Ill.
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  • 96
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structures of the antimalarials dihydroqinghaosu (2), artemether (3), and artesunic acid (7a) derived from qinghaosu were elaborated by 1H-NMR spectroscopy, and supported with X-ray data obtained for 2 and 3. Several new derivatives, useful for the chemical characterization of dihydroqinghaosu (2) and artesunic acid (7a), were prepared.
    Additional Material: 2 Ill.
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  • 97
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    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1562-1567 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The chain elongation of the deoxy-nitroribose 6 by a Michael addition to the vinyl-phosphonate 7 followed by a solvolysis gave the heptulosephosphonate 11 (87%). From 11, the key intermediates 15 and 16 (77%) were obtained by a highly diastereoselective reduction, followed by detritylation, periodate cleavage, and silylation. Methoxycarbonylation of 15 and 16 gave 17 and 18 which were converted into methyl shikimate (21; 79%) by intramolecular olefination and partial deprotection. Similarly, phosphonoylation of 16 gave 22 (99%) which was transformed into the diethyl phosphashikimate 2 (53% from 6).
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  • 98
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    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 2029-2030 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 99
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    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 2028-2028 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 100
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984) 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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