Bibliothek

Notizen: Reduction Degree in Photoredox-SystemsThe reduction degree is in many photoredox systems an invariant under irradiation. Therefore it represents an important degree of freedom in these systems. It is possible to define the reduction degree in such a systematic way, that it may also be applied for discussing complicated systems. It would be helpful to have selective electrode material for the examination of photoredox systems. We have succeeded in finding a selective electrode material for the iron in the iron/thionin system as well as in the iron/iodine system.

Notizen: (E)-6, 10-Dimethyl-9-methylidene-undec-5-en-2-one (1) has been isolated from Costus root oil. A total synthesis of this compound is reported.

Notizen: In order to investigate molecules and their interactions at interfaces we have developed a new spectroscopic technique based on integrated optics. A significant increase in sensitivity has been predicted and observed. We report here the details of the method and some preliminary spectra of organic dye molecules on thin films.

Notizen: Synthesis of 4-[3β, 14-Dihydroxy-5β, 14β-androstan-17β-yl]-3-pyrrolin-2-one (hothesimogenin)We describe the synthesis of 4-[3β, 14-Dihydroxy-5β, 14β-androstan-17β-yl]-3-pyrrolin-2-one (24-aza-24-desoxa-digitoxigenin) (7), starting from 3-O-acetyl-digitoxigenin (1).

Notizen: Thirty-three 1-β-D-pentofuranosylcytosine nucleosides were examined as substrates of crude cytidine deaminase from mouse kidney. In addition to previous observations of structural features in substrates required for enzymatic deamination [e.g., a free 3′-hydroxyl in the ‘down’ ribo (arabino)configuration] we find that: modification of the aglycon by substitution of a fluorine atom at C(5) results in a several-fold increase in the deamination velocity relative to cytidine whereas insertion of a methyl group at C(5) decreases the deamination velocity. This decrease is even more pronounced when a methyl group is substituted at C(6).Though xylosylcytosine and 3′-deoxy-3′-fluoro-xylo-C are not substrates for this deaminase, those xylofuranosylcytosines bearing good leaving groups (e.g., bromo, mesyloxy, or tosyloxy) at C(3′) are deaminated with substantial deamination velocities. This is probably due to a prior chemical reaction leading to arabino nucleosides bearing a free ‘down’ 3′-hydroxyl.A different situation is obtained with arabino nucleosides. Though ara-C and 2′-deoxy-2′-fluoro-ara-C are substrates for this deaminase, substitution of bulky groups (e.g., chloro, bromo, or mesyloxy) at C(2′) substantially decreases the susceptibility to deamination. An hypothesis is offered to explain these differences between xylo-and arabino-cytosines.The presence of a free hydroxyl group at position 5′ is not essential for enzymatic deamination.

Notizen: The 2-cyclohexene-imines 2b-2d and the hexahydroquinolines 5a, b are synthesized. n,π*-Excitation of these α,β-unsaturated imines leads to (E/Z) isomerization for compounds 2 while compounds 5 are unreactive. No cyclobutanes are formed from 2 or 5 under these conditions in the presence of olefins, and only 2d adds to 2,3-dimethyl-2-butene via the C=N bond to give an azetidine. On π,π* excitation 2 and 5 rearrange to the corresponding β,γ-unsaturated imines 8 and 9 with low efficiency. It is concluded that the failure of such imines to undergo [2+2]-photocycloadditions with olefins is not mainly due to radiationless decay via (E/Z) isomerization.

Notizen: Transamidation Reaction of Open Chaine Amino-amidesAmino-amides of type 11 with a primary amino and a N, N-disubstituted amide group isomerize under base catalysis completely to amino-amides 16 with a secondary amino and a N-monosubstituted amide group (see Scheme 3). Amino-amides having a secondary instead of the primary amino group are under base catalysis in equilibrium with the corresponding isomeres (Scheme 4). The opening of the proposed tetrahedral intermediate 13 (Scheme 3) takes place under stereo-electronic control (Schemes 5 and 6).

Notizen: Diazo coupling of 3,4-dimethoxyfuran with aryl diazonium ions3,4-Dimethoxyfuran (1) easily reacts with aryl diazonium chloride in aqueous pyridine in an expected 1, 4-addition reaction. From the isolable primary addition product pyridine is displaced by alcohols, phenols or thiols to yield 4-alkoxy- or 4-phenoxy- or 4-thiophenoxy-derivatives of 2,3-dimethoxy-2-buten-4-olide (3). Attempts to convert them into azo compounds by a base catalysed 1, 6-elimination reaction failed. Oxidation of 3a and 3c with DDQ results in the formation of the mono p-nitrophenylhydrazone of 3, 4-dimethoxymaleic acid anhydride. On the other hand, the thiophenoxy compound 3g is smoothly converted by MnO2 into the authentic furan-2-azobenzene derivative 5.

Notizen: Eine Vielzahl photophysikalischer Prozesse kann theoretisch durch ein Dreiniveaux-Modell beschrieben werden. Die hier kritisch diskutierten exakten Lösungen der klassischen wie auch der quantenmechanischen Behandlung können im allgemeinen weit voneinander abweichen. Es ist gezeigt, weshalb einerseits die klassische Kinetik bei den bekannten Systemen bisher erfolgreich war und welche Eigenschaften andererseits nötig wären, um die Diskrepanzen merklich in Erscheinung treten zu lassen. Insbesondere lässt eine kurze Analyse der Zeitabhängigkeit neue interessante Effekte in der Pico-und Subpicosekundengegend erwarten.

Notizen: Transamidation Reactions with Cyclic Amino-amidesLactames which are substituted at the nitrogen atom by a 3-aminopropyl residue are transformed under base catalysis to cyclic amino-amides enlarged by 4 ring atoms. The formed ring must be at minimum 12-membered. Scheme 2 illustrates this result: the 8-membered 7 is transamidated in 96% yield to the 12-membered ring 8 (in the presence of potassium 3-aminopropylamid in 1, 3-propanediamine), the 9-membered 10 to the 13-membered ring 11 (97%) and the 11-membered 14 to the 15-membered ring 15. Furthermore, the 13-membered ring 27 (Scheme 5) is transformed to the 17-membered 28. In the case of the 15-membered lactame 15 it is demonstrated that 14 is not formed back under the conditions of the transamidation.Large ring lactames which are substituted at the nitrogen atom by a 3-(alkylamino) propyl group lead under base catalysis to an equilibrium mixture, e.g. the 17-membered 26 is in equilibrium with the 21-membered 29. This result is similar to the behavior of the corresponding open-chain amino-amides [2].Because of transannular interactions, the 11-membered ring 2 is not stable: transamidation of the 7-membered 1 (Scheme 1) doesn't give the expected 2, but its water elimination product 3 in small yield. The N-tosyl derivative of 2, namely 20, is synthesized by an independent route (Scheme 3). Detosylation of 20 yields the 7-membered 1 instead of 2. Concerning the mechanism of this interesting reaction see Scheme 4.

Notizen: Les spectres IR. de cinq spiropyrannes benzothiazoliniques (ét solide et dissous) et les spectres Raman de trois d'entre eux (état solide) ont été enregistrés de 4000 à 400 cm-1 et ont permis une interprétation des vibrations moléculaires de ces composés. Une analyse plus sommaire, faite dans le but de caractériser la structure spiropyrannique a été étendue au moyen de la spectroscopie IR. à une série de vingt et un composés. L'étude IR. a également porté sur deux mérocyanines. Nous avons analysé et essayé d'interpréter les principales perturbations spectrales observées lors du passage d'un composé spiropyrannique (forme fermée) à la forme ouverte.

Notizen: The Crystal Structure of a Bridged 1,2,3-Oxadiazolidin-5-one Derivative3-(2-Allylphenyl)-4-phenylsydnone (1) undergoes in solution an intramolecular, 1,3-dipolar cycloaddition reaction to give 2-oxo-1-phenyl-1,5-methano-1,2,4,5,6,11-hexahydro [1,2,3] oxadiazolo [3,2-a] cinnoline (2). The unique 1,2,3-oxadiazolidin-5-one structure of this molecule has been proved by X-ray analysis. The crystal structure has been solved by direct methods and refined by full-matrix least squares calculations to R = 0,046. The crystal system is orthorhombic, space group Pbca, with unit cell dimensions a = 10,546, b = 15,482, c = 16,531 Å.

Notizen: [2+4]-Cycloaddition Products of 3,4-Dimethoxyfuran with Acetylenedicarboxylates and Their Transformations under the Influence of Rhodium(I) Catalysts3,4-Dimethoxyfuran (1) readily reacts with acetylenedicarboxylates (2) at room temperature in a [2+4]-cycloaddition to give a mono-(3) and several di-addition products. 90% of the latter consists of the endo-exo compound 4. Under the influence of catalytic amounts of [Rh(CO)2Cl]2 the mixture of mono- and di-adducts in methanolic solution is smoothly transformed into endo-5,5,6-trimethoxy-7-oxabicyclo [2.2.1]hept-2-ene-2,3-dicarboxylateAlle Verbindungen sind racemisch. Die Formeln stellen jeweils nur ein Enantiomeres dar. (5) , 3-hydroxy-4,5-dimethoxyphthalate ( 6) and (I R*, 2 S*, 4 R*, 5 R*, 7 R*, 11 R*, 12 R*) -5,8,8,9,12-pentamethoxy-3,6-dioxatetracyclo [5.3.1.1 2,5 . 0 4,11]dodec-9-ene-1,11-dicarboxylate ( 7).

Notizen: 2-Aminopyridines react with diethyl 2,5-dioxo-cyclohexane-1,4-dicarboxylate (diethyl succinylsuccinate) to give 7a,14a-diaza-6,7,7a,13,14,14a-hexahydroquino-[2,3-b] acridine-7,14-diones (5,7a,1,14a-tetraaza-6,7,7a,13,14,14a-hexahydropentacene-7,14-diones), which are aromatized to the title compounds. Oxidation of these with a mixture of sulfuric and nitric acids results in the formation of their respective 6,13-quinones, also obtained directly from 2-aminopyridines and diethyl 2,5-dichloro-1,4-benzoquinone-3,6-dicarboxylate. The chromophore of the title compounds is compared with that of quinacridones.

Notizen: A survey of the activity and selectivity of several catalysts for the amination of long-chain aliphatic alcohols with dimethylamine is given. The best results were obtained with Cu-catalysts whose long-term behaviour was investigated. The main reasons for catalyst decay are the irreversible adsorption of dimerization products and the thermal diffusive fusion of Cu-crystallites.

Notizen: The irradiation of the title compound 6 with UV. light and under photosensitized oxidation conditions yields products which are characteristic of the photo-oxidation of the enamide moiety of 6. In contrast to the situation encountered in the case of the irradiation of its carbocyclic and 4-oxa analogues 1 and 2, respectively, no compound resulting from a di-π-methane rearrangement of the Δ1,5(6)-unsaturated system of 6 has been so far detected.

Notizen: The irradiation of 17β-acetoxy-4-oxa-1,5-androstadien-3-one (12) yielded the two stereoisomeric spiro-lactones 13 and 14, which result from a di-π-methane photorearrangement. A third product, the oxa-anthrasteroid 15, was also isolated (Scheme 3).

Notizen: Preparation of substituted 2,3,4,5-Tetrahydro-1,2,4-triazine-6-carbonitriles and some of its Derivatives.The synthesis of 4-substituted 2-aryl-2,3,4,5-tetrahydro-5-imino-3-oxo-1,2,4-triazine-6-carbonitriles (3), 2-aryl-2,3,4,5-tetrahydro-3, 5-dioxo-1,2,4-triazine-6-carbonitriles (4) and some 3-thioxo-derivatives thereof by a novel approach is described. In addition some possibilities for the derivatisation of these compounds are given.

Notizen: The syntheses of adrenocorticotropin-(5-24)-eicosapeptide, -(6-24)-nonadecapeptide, -(7-24)-octadecapeptide, and -(8-24)-heptadecapeptide are described. Their biological activities on isolated adrenal cortex cells and adipocytes, on superfused adrenal tissue, as well as on the adenylate cyclase system of isolated cell membranes are summarized.

Notizen: Ab initio SCF and CI calculations on the cationic and neutral complexes of formaldehyde and lithium are reported. For the cationic complex CH2O/Li+, the stabilization energy of 41.7 kcal/mol obtained from the SCF calculation increases to 51.6 kcal/mol if a configuration interaction is introduced. For the neutral complex CH2O-/Li+, the C2v-conformer of the 2A1-state with the equilibrium bond distances of d(C—O) = 1.23 Å and d (O—Li) = 1.90 Å is calculated to be more stable than the 2B1-state with d (C—O) = 1.34 Å, and d (O—Li) = 1.65 Å. Charge transfer and polarization effects upon complex formation are discussed.

Notizen: The Synthesis of some 4-Nitroisoxazoles from Pseudonitrosites of ChalconesThe action of dinitrogen trioxide with α,β-unsaturated ketones of the chalcone type leads to pseudonitrosites (Table 1) which are cyclized to 4-nitro-3,5-diarylisoxazoles (Table 2).

Notizen: Ruspolia hypercrateriformis M.R.: Isolation and Structure Elucidation of New Pyrrolidine AlkaloidsThree new pyrrolidine alkaloids have been isolated from Ruspolia hypercrateriformis, which belongs to the plant family of Acanthaceae. The structure of the alkaloids ruspolinone (1), norruspolinone (2) and norruspoline (3) (Scheme 1) has been elucidated by means of spectroscopic data of the pure compounds and their derivatives, by chemical transformation fo 2 to 1 by methylation, by trans-formation of 3 and 2 to identical hydrogenation products, and by comparison of degradation products with synthetically prepared model compounds.

Notizen: A seven-step stereoselective synthesis of (±)-sweroside aglucone O-methyl ether (16a) was achieved in 27% overall yield from 1, 4-cyclohexadiene (4) and methyl diformylacetate (5). Secologanin aglucone O-methyl ether (18a) was then formed from 16a in 90% overall yield by a straightforward process. The key step in the synthesis was a [2+2]-enone-photoannelation of 4 and 5 to form the key intermediate 6 which possessed the desired cis-fused ring configuration, and all the caron atoms needed to complete the synthesis of 16a and 18a.

Notizen: Es wird gezeigt, dass bei der Racemisierung der aus natürlichem Colchicin leicht zugänglichen Schiff-Base 1, mit Kaliumhydroxyd in Methanol, neben Benzaldehyd, Benzylamin und (-)-N-Desacetylcolchicinsäure (4), auch die beiden tricyclischen Verbindungen 2 order 5 erhalten werden. Die Überführung des Ketimins 2 in das Diketon 5 gelingt leicht durch saure Hydrolyse. Letzteres kann mit Benzylamin unter den gewählten Racemisierungsbedingungen direkt in (-)-N-Desacetyl-colchicinsäure (4) übergeführt werden. Ein Vergleich der NMR.-Spektren von 5 und seiner beiden Methyläther 6 und 7, mit Substanzen der Colchicin-Reihe, gestattet die Identifizierung von 6 als 7-Oxo-desacetamidoisocolchicin und von 7 als 7-Oxo-desacetamidocolchicin, erlaubt jedoch keine eindeutige Zuordnung der beiden Sauerstoffunktionen im Ring C des Diketons 5. Eine solche konnte jedoch durch eine Röntgenanalyse weiter präzisiert werden. Diese ergibt nämlich, dass das Diketon 5 ein durch Wasserstoffbrücken stabilisiertes Dimeres der Tautomeren 5a (Ring C wie Isocolchicein) und 5b (Ring C wie Colchicein) darstellt.

Notizen: Synthesis of Two Naturally Occurring 10-Membered Ring Lactones: (±)-Phoracantholide J and ITwo 10-membered ring lactones 7 and 11 from the metasternal secretion of the eucalypt longicorn Phoracantha synonyma have been synthesized by the following method. Reaction of the dilithium derivative of 4-pentynoic acid (3) with 4-tetrahydropyranyloxy-1-pentylbromide (2), followed by removal of the protecting group and by esterification with diazomethane, gave methyl 9-hydroxy-4-decynoate (4; s. Scheme 1). Partial hydrogenation of the triple bond in 4 with Lindlar palladium catalyst, followed by saponification lead to cis-9-hydroxy-4-decenoic acid (6). The 9-hydroxydecanoic acid (9) was synthesized by addition of methyl magnesium iodide to methyl 8-formyloctanoate (8) followed by saponification (s. Scheme 2). The hydroxy acids 6 and 9 were converted into the S-(2-pyridyl) thioesters and cyclized in dilute benzene solution under the influence of silver ions to yield (±)-phoracantholide J (7) and I (11) in 74 and 71% yield, respectively.

Notizen: Conformational analysis of 5,6,7,8-tetrahydropteroic acid and 5,6,7,8-tetrahydro-L-folic acidIn the 360-MHz-1H-NMR.-spectrum of (6R, S)-9,9-dideuterio-5, 6, 7, 8-tetrahydropteroic acid (racemic) (XIII) (AMX-System, Fig. 4) and (6R, S)-9,9-dideuterio-5, 6, 7, 8-tetrahydro-L-folic acid (diastereomeric) (XVI) the Ha-C(6) and Ha-C(7) show a vicinal coupling constant of 6,7 Hz and the Ha-C(6) and He-C(7) one of 3,2 Hz. The first coupling constant provides evidence for an approximate trans-diaxal arrangement of Ha-C(6) and Ha-C(7), and the second for a gauche conformation of Ha-C(6) and He-C(7). The tetrahydropyrazine ring in the racemic 5, 6, 7, 8-tetrahydropteroic acid (III) and in the diastereomeric 5, 6, 7, 8-tetrahydro-L-folic acid (XVII) exists therefore in a half-chair conformation with a pseudoequatorial position of the side chain at C(6) (Fig.5).

Notizen: On the Fischer-Indole Reaction. II. Thermal and Acid Catalysed Indolization of 1′-Alkenyl-2′-methyl-2′-phenylacetohydrazidesSeven different 1′-alkenyl-2′-methyl-2′-phenylacetohydrazides, 6a-g, have been prepared by treatment of the methylphenylhydrazones 7 of appropriate ketones and aldehydes with acetyl chloride in pyridine. At 170° 6a-g are transformed into the N-methylindoles 3a-g and acetamide in moderate yield. N-Methylaniline is the other major reaction product indicating that homolytic cleavage of the weak N, N-bond in 6 is a major primary reaction step. It is likely but not proven that the N-methylindoles 3 are formed in a reaction sequence initiated by an uncatalysed concerted [3, 3]-sigmatropic rearrangement.Upon treatment of 6 with 0.5N dichloroacetic acid in anhydrous acetonitrile at room temperature a quantitative conversion to 3 is observed, interpreted as proceeding by a charge induced [3, 3]-sigmatropic rearrangement of protonated 6 in the rate determining step. The ketone derivatives 6a-e (R1 = alkyl) react 40-1000 times faster with acid than the aldehyde derivatives 6f and 6g (R1 = H). This is rationalized as a consequence of the increased basicity of 6a-e relative to 6f and 6g caused by a steric effect.

Notizen: Flexible model results for the —NH2 inversion in vinylamine are compared with microwave data published by Lovas et al. [3]. The information available on the spacing of inversion levels is found to be sufficient to rule out a planar equilibrium structure. Shifts of rotational constants upon excitation of the inversion are calculated for two predicted paths of motion derived from PRDDO geometry optimization results obtained by MiiIler & Brown [2]. Partial geometry optimization yields a path inconsistent with experiment but the path obtained from complete optimization produces shifts in excellent agreement with the observed shifts. A potential energy function compatible with experimental data on spacing of inversion levels is calculated from the observed inertia defects. The inversion angle at equilibrium is slightly smaller than the angle predicted from PRDDO calculations, and the barrier to inversion, ΔV = 1.08 ± 0.07 kcal/mol, is approximately half the PRDDO value.

Notizen: Iron Pentacarbonyl Induced Reactions of Norbornadiene and Substituted OlefinsThe photochemical reaction of norbornadiene and α, β-unsaturated nitriles, esters and amides in the presence of Fe(CO)5 was studied. Nitriles furnished the dinorbornenyl ketones 2a-c (Scheme 1). Esters led to an addition of a norbornene moiety to the double bond giving the substituted α, β-unsaturated esters 10a and 10b (Scheme 5). Methacrylamide and methyl β-aminocrotonate gave the cyclopentanone derivatives 14 and 17, respectively (Schemes 7 and 8). The reaction was in all cases highly stereoselective with general exo-substitution on the norbornadiene. The attack on the unsymmetric olefins occurred regiospecifically at that point of the double bond which was furthest away from the functional group. A plausible mechanism for these reactions is suggested in Schemes 10 and 11.

Notizen: Complexes of lanthanoid trinitrates Ln(NO3)3 with 15-crown-5 ether 1 (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd) and with 18-crown-6 ether 2 (Ln = La, Ce, Pr, Nd) having a 1:1 stoichiometry as well as 4:3 complexes with 2 (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd) have been synthesized and characterized. All the isolated complexes are solvent free. At 170-220° the 1:1 complexes of 2 are quantitatively transformed into 4:3 complexes. X-Ray powder diagrams of the neodymium complexes with 2 indicate that both the 1:1 and 4:3 complexes are genuine compounds. All the 1:1 complexes show a characteristic IR. absorption band at 875-880 cm-1 absent from both the spectra of the free ligands and of the 4:3 complexes.The spectroscopic properties (IR. and electronic spectra, fluorescence lifetimes) of the complexes and the low magnetic moments of the Ln(III) ions in the complexes with Ln = Ce-Eu are indicative of a strong interaction between the lanthanoid ions and the crown ethers 1 and 2.

Notizen: The preparation of the new organic metallic compound (TSeT)2-I is reported. The crystal structure of the free donor, TSeT, is discussed and compared with the crystal structure of (TSeT)2-I. The latter has the orthorhombic space group P21212 and hence is not isomorphous with the analogous compounds (TSeT)2-Cl and (TSeT)2-Br, described by Shchegolev et al. [4].In contrast to those complexes (TSeT)2-I consists of only one set of crystallographically equivalent chains and therefore its transition to the low-temperature conducting state (Fig. 6) is also of different type.The d. c. resistivity at 300 K ranges from 10-3 to 1.5 ·. 10-4 Ω cm. The temperature dependence of the d.c. resistivity of the title compound is given: in the temperature range from 300 to 80 K the normalized d.c. resistivity is described by ρ(T)/ρ(300) ∝ T1.7. Between 80 and 70 K a slight deviation from the above law has been detected which is taken as an indication of a phase transition; its nature is, however, not yet definable. The low-temperature conducting state reached at about 70 K shows an almost constant resistivity in the interval 60 K to 45 K. Its normalized d.c. resistivity in the range 4.5 K-50 K is described by ρ(T)/ρ(300) ∝ (T-Tm)3, with Tm = 50 K. The value of the normalized resistivity extrapolated to O K is 0.75.

Notizen: Identification of short side chain sterols in the sponge Damiriana hawaiianaThe steroidal composition of the sponge Damiriana hawaiiana is examined. Twenty-seven components are identified. In addition to the C26-C29, Δ5-mono and diunsaturated sterols, the sponge contains sterols without side-chain: androsta-5, 16-dien-3β-ol(1), androst-5-en-3β-ol(2); sterols with a non-functionalized side-chain consisting of two, three, four, five and six carbon atoms: pregna-5, 20-dien-3β-ol(5), pregn-5-en-3β-ol(6), 23, 24-bisnor-chola-5, 20-dien-3β-ol(7), 23, 24-bisnor-chol-5-en-3β-ol(8), 24-nor-chol-5-en-3β-ol(10), chol-5-en-3β-ol(11), 26, 27-bisnor-cholest-5-en-3β-ol(12), and sterols possessing a short oxygenated side-chain such as 3β-hydroxy-androst-5-en-17-one(3), androst-5-en-3β, 17β-diol(4) and 3β-hydroxy-26, 27-bisnor-22-trans-cholesta-5, 22-dien-24-one(14). The probable biological or dietary origin rather than artifact production of these hitherto undescribed components from marine sources is supported by their relatively high concentration and their relative proportions, both very different from those expected for autoxidation.

Notizen: On the Photochemistry of Sydnones and 1,2,3,4-Oxadiazolin-2-onesThe photochemical behaviour of several 3,4-disubstituted sydnones (cf. Scheme 5) dioxane solution was investigated. The pure sydnones give, as was already reported [2-6], 2,4,5-trisubstituted 1,2,3-triazoles 2 (cf. Scheme 1) in 25-30% yield. In the presence of dipolarophiles (cf. Scheme 1) pyrazole derivatives 3 or 4 are formed which can be taken as a proof for the formation of nitril-imines 5 as primary products in sydnone photochemistry. Since irradiation of 2-[15N]-3, 4-diphenyl-sydnone (2-[15N]-15) in dioxane leads to the formation of 1,3-[15N]-2,4,5-triphenyl-1,2,3-triazole (1,3-[15N]22; cf. Scheme 10), nitril-imine formation must be induced by the creation of a bond between N(2) und C(4) in the excited sydnones (cf. Scheme 22). The irradiation of sydnones in dioxane solution in the presence of carboxylic acids yields N′-acylhydrazides in 50-70% (cf. Scheme 14), the formation of which can be explained by addition of the acids to the nitril-imines and rearrangement of the primarily formed anhydride monohydrazones (Scheme 15). By analogy, the formation of 1-benzoyl-2-(t-butyl)-4-phenyl-1,2-diazetidin-3-one (14; Scheme 4) during the photolysis of 3-(t-butyl)-4-phenylsydnone (12) in benzene solution (cf. [5b]) may also be explained: Sydnone 12 undergoes two different photoreactions leading by loss of carbon dioxide to the corresponding nitril-imine 5 (R=t-C4H9, R′= C6H5) and by loss of isobutylene to a 1,2,3-oxadiazolin-5-one of type 48 or 49 which isomerizes to yield diazophenylacetic acid (51; cf. Scheme 17). Reaction of both products (5 and 51) results in the formation of the N′-acylhydrazide 52 (Scheme 18) which may cyclize after loss of nitrogen to yield the diazetidinone 14 in a carbene type reaction. The triazoles 2 are formed photochemically from the corresponding 1,2-bisazo-ethylenes 64 (Scheme 26) which arise from a direct ‘head-to-head’ dimerization of the nitril-imines 5. This type of reaction seems to be common to all nitrilium betaines (Schema 30). The photolysis of the 2,4-disubstituted 1,3,4-oxadiazolines 76 does not lead to nitril-imines 5 (cf. [11]). On the contrary, loss of carbon monoxide induces the formation of azoketones 77 (cf Scheme 31), which may be photo-reduced to yield hydrazides or may undergo cleavage of the N, acyl bond to form derivatives of1,2-diketones (cf. Scheme 32).

Notizen: In heterolytic dediazoniations arenediazonium salts form aryl cations. The reaction rates are relatively slow; they depend only to a small extent on the solvent. It is shown that the solvents in which the heterolytic dediazoniation mechanism is predominant have a low nucleophilicity, whereas in solvents of high nucleophilicity homolysis of arenediazonium salts, i.e. the formation of aryl radicals and related intermediates, is favoured. Under comparable conditions, homolytic rates are faster than the corresponding rates of heterolysis. Homolysis is strongly enhanced by addition of nucleophiles which form relatively stable radicals by electron transfer. The ability of additives to catalyze homolysis of arenediazonium salts can be explained using the concept of a nucleofugicIn the original proposal [32] we used the word nucleofugal. In keeping with a forthcoming proposal on nomenclature in physical organic chemistry by Commission III.2 (Physical Organic Chemistry) of IUPAC we now use the word nucleofugic. homolytic leaving group.

Notizen: A synthesis of tricyclo [4.2.2.22,5]dodecane (19), a novel tricyclic C12H20 compound, is described. The key intermediate ketone 13 was prepared either from the C10-photodimer 1 of cyclopentadienone or the C11-cycloaddition products 11 and 12. 13 was also transformed to tricyclo [4.2.2.12,5]undecane (8).

Notizen: The Chukrasines A, B, C, D and E, Five New Tetranortriterpenes From Chukrasia tabularis A. JUSSFive new tetranortriterpenes, chukrasins A, B, C, D and E, have been isolated from the wood of Chukrasia tabularis A. JUSS. On the basis of spectral and chemical evidence structures 1a-1e were assigned to the new compounds.

Notizen: The reactions of SnCl2 with the complexes cis-PtCl2P2, P=trialkyl and triaryl phosphines and phosphites, in CDCl3 and CD2Cl2 have been studied using 31P and 195Pt NMR. methods. For equimolar amounts of Sn and Pt, products of the type PtCl(SnCl3)P2 are formed with the complex geometry depending on the nature of P. For P=PEt3 and P(OPh)3, further addition of SnCl2 produces trans-Pt(SnCl3)2 complexes. The syntheses of trans-PtCl(SnCl3) (PEt3)2 and trans-Pt(SnCl3)2 (OPh3)2 are described.

Notizen: On the Activation of Partially Silylated Carbohydrates Using Triphenylphosphane/DiethylazodicarboxylateReaction of methyl α-D-glucopyranoside (1) with two equivalents of t-butyldimethylchlorosilane yields methyl 2,6-bis[O-(t-butyldimethylsilyl)]-α-D-glucopyranoside (1a) and methyl 3,6-bis[O(t-butyldimethylsilyl)]-α-D-glucopyranoside (1b) in a ratio of 4:1. The anomeric β-pyranoside 2 affords methyl 2,6-bis[O(t-butyldimethylsilyl)]-β-D-glucopyranoside (2a) and methyl 3,6-bis[O(t-butyldimethylsilyl)]-β-D-glucopyranoside (2b) in nearly equal amounts. 2b is isomerized to methyl 4,6-bis[O(t-butyldimethylsilyl)]-β;-D-glucopyranoside (2c) (83%) and 2a (10%) with triphenylphosphane/diethylazodicarboxylate. Structures were assigned by NMR.-analysis and CD.-analysis of the corresponding benzoates 1c, 1d and 2d and of the acetates 2e and 2f.1a is transformed into methyl 4-azido-2, 6-bis[O(t-butyldimethylsilyl)]-4-deoxy-α-D-galactopyranoside (3) with triphenylphosphane/diethylazodicarboxylate/HN3. 2a and 2c yield the 3-azido-allosides 5 and 7 respectively under similar conditions. The activation by triphenylphosphane/diethylazodicarboxylate is high enough to introduce also p-nitrobenzoate groups with inversion of configuration at the reaction center. By this way 1a and 2a give methyl 2, 6-bis[O(t-butyldimethylsilyl)]-4-O-p-nitrobenzoyl-α-D-galactopyranoside (4) and methyl 2, 6-bis[O-(t-butyldimethylsilyl)]-3-O-ptrobenzoyl-β-D-allopyranoside (6) respectively. For elucidation of structures the acetate derivatives 3a-7a were prepared.

Notizen: Some sugar phosphates, phosphonates and phosphine oxides, Preliminary communicationSome new phosphates of 1, 2-O-isopropylidene-α-D-ribofuranose have been prepared. Reactions of 3-C-cyanomethylidene-3-deoxy-1, 2-O-isopropylidene-5-O-trityl-α-D-erythro-pentofuranose (9) have been studied. On treatment with phosphorus nucleophiles, 9 led to phosphorus bearing branched-chain sugar derivatives. Branched-chain cyanosugars as 15 and 16 prepared by cis-vic-dihydroxylation of 9 constitute interesting potential precursors of new types of cyclic sugar phosphates.

Notizen: By means of contact angle measurements, it has been shown that compact alkyl-dimethyl-siloxy layers can be obtained on the surface of acid leached glass using the method previously developed for fume silica. Subsequently, a series of densest possible alkyl-dimethylsiloxy layers were prepared having non-branched alkyl substituents, CzH2z+1, (with z=1, 2, 3, 6, 10, 14, 18 and 22) and wetting angles were measured as a function of the temperature. On surfaces coated with longer alkyl substituents the formation of mixed crystals, consisting of the sparse chemically bonded alkyl layer and a n-alkane acting as a wetting agent, has been observed at low temperatures. At higher temperatures such surfaces appeared to be «molten», and at the same time swollen by the wetting agent. Equations have been derived to deduce the free surface energies and to account for the wetting properties of rough and swollen surfaces. Application of the results to the data presented in this paper revealed that glass surfaces covered with short alkyl chains (methyl, ethyl and propyl) are rough and those covered with long chains (tetradecyl, octadecyl and docosyl) are swollen. Surfaces formed by hexyl- and decyl-dimethylsiloxy substituents exhibit intermediate properties.

Notizen: The enantiomerically pure (+)-3-methoxy-1, 3, 5 (10)-estratrien-11, 17-dione 11 (with trans-anti-trans configuration) was synthesized in a highly stereocontrolled fashion from (±)-t-butyl 4-methoxy-1-benzocyclobutene carboxylate (8) and the (+)-carboxylic acid 6, obtained from 4 in two steps, followed by one crystallization of the (+)-ephedrine salt. The key step 10→11 (Scheme 2) involves a thermal intramolecular cycloaddition reaction.

Notizen: Stereochemical Course of the Formation and Cleavage of the Co—C Bond in a Vitamin B12 ModalThe electrosynthesis and properties of a chiral cobalt alkyl complex 4 are described. The reductive cleavage of the Co-C bond occurs with retention of configuration at the C-atom.

Notizen: Cob (I)alamin as Catalyst 2. Communication [1]. Reduction of Saturated Nitriles in Anhydrous SolutionUsing cob (I)alamin as homogenous catalyst in glacial acetic acid saturated nitriles are reduced following the path of a reductive amination. The results prove the presence of an intermediate imine during the reduction of saturated nitriles with cob (I)alamine.

Notizen: Reaction of Diphenylcyclopropenone with β-Carbonyl-enolates. I. Use of Acetylacetone, Methyl Acetoacetate, 2-Ethoxycarbonyl-cyclododecanone and Dimethyl MalonateThe reaction of the sodium salts of acetylacetone (6), methyl acetoacetate (7), 2-ethoxycarbonyl-cyclododecanone (8), dimethyl malonate (19) and its methyl derivative 20 with diphenylcyclopropenone (5) in dimethylformamide at room temperature led to the unsaturated γ-lactones 14, 15, 17, 22 and 36. In the case of dimethyl malonate (19), the halfester 21, the acyl-malonic ester 24 and the indenone-malonic ester 23 were also isolated.Several intermediates and the final products were characterised by reactions and spectroscopically. A general mechanism is discussed for the addition of cyclo-propenones (1) to the enolate salts of β-dicarbonyl compounds 4 involving the bicyclic lactone-enolates 18 and 32 as intermediates. The products formed via 18 and 32 are considered to be the result of an attack of one of the oxygen atoms of the β-carbonyl-enolate anion (4), the product 24, on the other hand, of the attack of the α-carbon atom of 4; in both cases the attack is on the carbonyl C-atom of 5.

Notizen: Mechanistic studies on the collision-induced fragmentations of quaternary ammonium ionsThe collision-induced fragmentation behaviour of field desorbed quarternary ammonium ions has been investigated. A main reaction of these ions is the cleavage of the N—C bond accompanied by hydrogen rearrangement, i.e. alkane loss from the tetraalkyl substituted ammonium ions of the iodides 1, 2 and 3, respectively, Deuterium labelling indicates that the hydrogen transfer to the leaving group occurs to the extent of about 80% from the α-position and about 20% from the other positions of an alkyl group. Pronounced heterolytic cleavage of the N—C bond is observed in the benzyl substituted ammonium ion of 4. The β-phenylethyl substituted ammonium ion of 5 shows a homobenzylic heterolysis, possibly yielding the phenonium ion j.

Notizen: 1, 5, 6, 7-Tetrahydro-2H-[1, 4]diazepin-5, 7-diones from Malonimides and 3-Dimethylamino-2, 2-dimethyl-2H-azirineReaction of the aminoazirine 1 with malonimides of type 7 in 2-propanol at room temperature leads to the 1,4-diazepine derivatives of type 9 (Scheme 3). The structure of 6, 6-diethyl-3-dimethylamino-2,2-dimethyl-1,5,6, 7-tetrahydro-2H- [1,4] diazepin-5, 7-dione (9a) has been proved by single crystal X-ray analysis (Chapter 4). Reduction of the 7-membered heterocycle 9a with sodium borohydride yields the perhydro-[1,4]diazepin-5, 7-dione 10, while 9a in ethanol at 60° undergoes a ring contraction to the 4 H-imidazole derivative 11a (Scheme 4): Mechanisms of these two reactions are discussed in comparison with previously reported reactions (Chapter 5).

Notizen: Synthesis and Photochemistry of Sydnonazomethines-(4)Sydnon-4-aldehydes 1-3 react with prim. amines or N-sulfinylanilines to sydnon-azomethines. The i.r.-spectra are discussed. Sydnonazomethines undergo a photoinduced E/Z-isomerisation, at room temperature; a rapid thermic back-reaction (Z/E-isomerisation) takes place, however. The photostationary states at -75°C are analyzed. The rate constants of the thermic back-reaction at 18°C are measured by means of flash-photolysis. The quantum yields for the E/Z-isomerisation (at -75°C) and the photolytic decomposition have the value of 〉0,1 and 〈10-3 respectivly.

Notizen: On the Preparation of Isocyanatoderivatives of Aliphatic DiethersA method for the preparation of some isocyanates of aliphatic diethers of the general formula: CH3(NCO)—O—[CH2]n—O—CH(NCO)CH32a-e, where n = 1-5 has been reported. The syntheses conditions, properties, as well as the conversion of the obtained diisocyanates into the new urea derivatives were described.

Notizen: A Simple Calculation Method for the Estimation of the Inductive Effect of Different SubstituentsA new method without great mathematical operations for the estimation of the inductive effect of any substituents is described. The starting values are the electronegativities and the bond lengths of the atoms of the corresponding substituent.The ID values, received by this method show a good correlation with the known electronic parameters (F, σ′, σ*, σI and σqI) and with the velocity constants and equilibrium constants of chemical reactions, respectively.

Notizen: d-N.M.R.-Investigation of the Restricted Rotation at the -Bonding Increment. X. N-Substituted Thiocarbamic acid-O-Phenyl- and S-EthylestersThe free enthalpies of activation of the restricted rotation at the partial -double bond in thiocarbamic acid esters have been determined for (R1 = methallyl; R2 = me, et, iso-pr, cycl. hex; X = S and Y = O—C6H5 respectively X = O and Y = S—C2H5). The results have been compared with values, earlier observed for other mono- and dithiocarbamic acid esters, substituted at nitrogen analogously.

Notizen: Reactions of Alkenes in the Presence of Tungsten- and Molybdenum-containing Ziegler-Natta-CatalystsIn connection with investigations of reactions of alkenes under the conditions of metathesis we studied the reactions of a mixture of 2-pentene/toluene in presence of the catalytic systems WCl6/EtAlCl2 and MoCl5/EtAlCl2 in homogeneous liquid phase.Alkylation of toluene, metathesis of 2-pentene and also indirect isomerisation of double bonds have been determined in dependence of the molar proportions of 2-pentene/MeClx, toluene/2-pentene, and MeClx/EtAlCl2, the addition order (“formation”) of reactants, the “building time” of catalytic system and the reaction time.Compositions of the reaction mixtures have been determined by GLC.

Notizen: Synthesis of Nitro- and Amino-Substituted Thiobenzamides by Thiolation Reactions with Elemental Sulfur at Mild ConditionsThe Synthesis of thiobenzamides 2-7 by basecatalyzed thiolation of nitro-benzyl-halides (type 1), especially at low temperatures, and the selective synthesis of p- and m-nitro-thio-benzamides (2, 3) or p-and m-amino-thiobenzamides (5, 6), respectively, are described. o-Nitro-benzylhalides (→ 4, 7) are less reactive than p- and m-nitro-benzylhalides.The reaction of nitrobenzylhalides (type 1) with elemental sulfur and amines occuring at low temperatures to give 2-4 leads via structures of the type 11, 15 and 16.

Notizen: 13C-N. M. R. Chemical Shifts of Aromatic Sulfonamides

Notizen: MO-LCAO Calculations on Polymethines. IX. On the Chromaticity of Coupled Oxonol and Cyanine DyesStreptopolymethines display low-energy electronic transitions with a high transition probability and possess, moreover, a high capability to accept or to release electrons. These properties account for the absorption colour of polymethine dyes consisting of two molecular fragments. Scope and limitations of a composite-molecule approach can be recognized by subjecting the electronic wavefunctions to the so-called configuration analysis. Colour-structure relationships are derived from inspection of key orbital interactions between the molecular fragments.

Notizen: α-Substituted Phosphonates. XXXI. The Reaction of N,N,N′,N′-Tetramethyl Chloroformamidinium Chloride with P(III) CompoundsN,N,N′,N′-Tetramethyl chloroformamidiniumchloride (4) does not react with triethyl phosphite (TEP) or isopropyl diphenylphosphinate to give the expected bisphosphoryl derivatives 7 and 11, respectively, but primarily the monophosphorylated amidinium salts 6 and 10 respectively. The phosphine oxide 10 is stable, while 6 undergoes an elimination of ethyl chloride to the betain 8. Even under more drastic conditions the reaction of 4 or 8 with TEP does not lead to the expected bis(dimethylamino)bisphosphonate 7, but to the monoaminated bisphosphonate 1, involving a reduction step. Similar reduction has been observed under mild conditions in Michaelis-Arbusov reaction of dichloromethylenimonium chloride, yielding the expected trisphosphonate 2 and the bisphosphonate 1 as a by-product.

Notizen: 6-Substituted 2,4-diphenyl-1,3,4-oxadiazin-5-onesBy reaction of dichloro acetylchloride and β-N-phenyl benzhydrazide 6-chloro-1,3,4-oxadiazin-5-one 2 is accessible which reacts with potassium phthalimide and potassium succinimide, respectively, to from 6-phthalimido- and 6-succinimido 2,4-diphenyl-1,3,4-oxidiazinon (3 and 4), respectively. The phthalimido substituent can be substituted by benzylamine or hydrazine.

Notizen: Untersuchungen an Lactamen. II. Synthese neuer β-Lactame

Notizen: Reactions of β-Chlorovinylaldehydes. IV. Syntheses of 2-Formylmethylene-2H-1-benzopyranes and Benzopyrylocyaninedyes from β-Chlorovinylaldehydesα-Alkyl-β-chlorocrotonaldehydes react with salicylaldehyde in methanolic solution of potassium hydroxide forming 2-formyl-methylene-2H-1-benzopyranes 1. The corresponding benzopyryliumsalts 2 which are easily available from 1 and strong acids, exist in the enolic form. They react at room temperature in alcoholic solution with elimination of ethyl formiate, yielding dark blue compounds which were identified as 2,2′-benzopyrylotrimethincyanindyes 3. The structure of 3 has been elucidated by means of 1H-n.m.r.-spectra.

Notizen: Kinetics of Hydrogen-Deuterium-Exchange in the Methin Chain of Simple PolymethinesSimple polymethines are deuterated in the methin chains at positions of high π-electronic density. The rate constants of this reaction were determined by 1H-n.m.r. spectroscopy taking into account hydrolytic side-reactions. The rate constants of the H/D exchange correlate well with the HMO localization energies at the methin atoms concerned.

Notizen: Thiophosphorylierung von Alkoholen im Vier-Komponenten-System: Ph3P/CCl4/(C2H5O)2P(S)OH bzw. (C2H5O)2P(S)SH/(C2H5)3NBei der Reaktion in dem Vier-Komponentensystem (Thio- und Dithiophosphorsäure-O, O-diethylester 2 bzw. 6 -Triphenylphosphin-Tetrachlorkohlenstoff-Triethylamin) und Alkoholen entstehen die Thiolester 3/4 bzw. 7/4 als Hauptprodukte. Ein möglicher Mechanismus der nicht eindeutig verlaufenden Thiophosphorylierungsreaktion wird formuliert. Es werden Thiophosphoryloxyphosphonium-Komplexe als Zwischenprodukte, ihr dynamisches Gleichgewicht und der Zerfall postuliert. Analoge Komplexe, die sich in verwandten Reaktionen als Zwischenprodukte bilden, wurden ebenfalls untersucht.

Notizen: Insertion of CS into AminosilanesDithiocarbamats 2, 3 and 4 with Si—S bondings can be prepared by the insertion of CS2 into aminosilanes 1. It is shown that more than one Si—N bond in a molecule are able to react with CS2. The reactivities of the aminosilanes depend on the basicity of nitrogen. The insertion reaction can be observed by 1H n. m. r. spectroscopy.

Notizen: A Comparison between Different Coupling Methods in the Synthesis of the N-terminal Nonapeptide of the Sheep Insulin-A-Chain by Fragment Condensation on a Solid SupportThe N-terminal protected nonapeptide of the sheep insulin-A-chain, benzyloxycarbonyl-glycyl-isoleucyl-valyl-γ-tert.-butyl -glutamyl-glutaminyl-S-benzylcysteinyl-S-benzylcysteinyl- alanyl-glycine-methylester, was prepared by 4 + 2 + 2 + 1 - P fragment condensations on a solid support by means of various coupling methods, and detached from the matrix by transesterification with methanol. The best results of the fragment couplings have been obtained by means of the dicyclohexylcarbodiimide/pentafluorphenol-complexNomenklatur und Abkürzungen nach den Regeln der IUPAC-IUB-Commission on Biochemical Nomenclature, J. Biol. Chem. 241, 2491 (1966) u. 247, 977 (1972); weitere Abkürzungen: HOSu = N-Hydroxysuccinimid, HOBt = N-Hydroxybenzotriazol, HOOBt = 3-Hydroxy-4-oxo-3,4-dihydro-1,2,3-benzotriazin, EEDQ = 1-Ethoxycarbonyl-2-ethoxy-1,2-dihydrochinolin, Woodwards Reagens = 2-Ethyl-7-hydroxy-1,2-benzisoxazolium-tetrafluoroborat, NEPIS = 2-Ethyl-5-phenyl-1,2-oxazolium-3′-sulfonat, DCCI = Dicyclohexylcarbodiimid, PfpOH = Pentafluorphenol, Ph3P = Triphenylphosphin, (PyS)2 = 2,2′-Dipyridyldisulfid, Z = Benzyloxycarbonyl-, Nps = o-Nitrophenylsulfenyl-, Boc = tert.-Butyloxycarbonyl-, Bzl = Benzyl-, -OMe = Methylester, -OBut = tert.-Butylester, THF = Tetrahydrofuran, DMF = Dimethylformamid, Et3N = Triethylamin, NMM = N-Methylmorpholin, TFA = Trifluoressigsäure. and by the oxidation-reduction condensation method wich 2,2′-dipyridyldisulfide and triphenylphosphine. Using dicyclohexylcarbodiimide/hydroxybenzotriazole or EEDQ the optical purity results were insufficient and the yields of the fragment condensations much smaller in comparison with the other mentioned methods.

Notizen: A Method for the Quantitative Control of Solid Phase Reactions in the Peptide SynthesisA quantitative control-method of partial steps of a solid phase peptide synthesis is described, based on a hydrazinolytic cleavage of protected peptides from the solid support. A separation of the peptide hydrazides by gelchromatography on sephadex G 15 in dimethylformamide and a quantitative evaluation of the hydrazide-content in the elution fractions is reported, which permits the control of the Nα-deprotection step in the same way as the evaluation of the coupling yields of the desired sequence. The new method is discussed for the example of two solid phase syntheses of the pentapeptide N-tert.-butyl-oxycarbonyl-L-valyl-S-benzyl-L-cysteinyl-L-alanyl-L- leucyl-O-benzyl-L-tyrosine hydrazide.

Notizen: 1H and 13C n.m.r. Spectroscopical Measurements and HMO-π-Calculations to the π-Electronic Structure of p,p′-Disubstituted trans-Stilbenes and Substituted trans-β-Styryl-methyl-SulfonesThe 1H and 13C n.m.r. spectra have been measured for a series of donator-acceptor-disubstituted trans-stilbenes 1 and monosubstituted β-styryl-methyl-sulfones 2. The 13C n.m.r.-signals have been identified by comparison with empirical calculated chemical shifts and quantum chemical determined HMO-π-electrons densities. The influence of substitutents to the experimental chemical shifts are discussed in detail. For 1 and 2 exist linear correlations between chemical shifts and HAMMETT values, and π-electron densities, respectively.

Notizen: A Convenient Synthesis of Methionin-EnkephalinAn efficient synthesis of methionin-enkephalin has been developed by prolongation of the C-terminal amino acid methylester using Boc-Phe-OHNomenklatur und Abkürzungen nach den Regeln der IUPAC-IUB-Commission on Bichemical Nomenclature: Hoppe-Seyler's Z. physiol. Chem. 348, 256 (1967), J. Biol. Chem. 247, 977 (1972); weitere Abkürzungen: DCC = Dicyclohexylcarbodiimid, HOBt = 1-Hydroxybenzotriazol, DMF = Dimethylformamid. , Boc-Gly-Gly-OH and Boc-Tyr-OH.

Notizen: Reaction of Cyclobutendiones. LIII. New Heterocyclic Systems by Reaction of 4-[-(z)-Benzylidenene]-2,3-diphenyl-cyclobut-2-enone with DiazomethaneThe addition of diazomethane to stable 4-alkylidene-cyclobut-2-enones gives at the same time the 1:1 adducts 2, and under elimination of 1 mole nitrogene the 1:2 adducts 3 respectively the 1:3 adducts 4.

Notizen: 1,2,3-Triazabutadienes. VIII. Investigations of the Mechanism of the Sensitized Photoisomerization of 1-Aryl-3-[3-methyl-benzthiazolinyliden-(2)]-triazenes.It is possible to sensitize the photochemical cis-trans-isomerization of triazabutadienes by sensitizers with tripletenergies ranging from 40 to 80 kcal/mol. It was proved by flash photolysis that triazabutadienes quench the triplet states of sensitizers. The dependence of the photostationary state on the triplet energy of the sensitizer as well as the dependence of the quantum yields of the sensitized photoisomerization on the concentration of triazabutadiene were investigated, and the desactivation ratios of the sensitized photoisomerization were determinated. The found correspondence of desactivation ratios of the direct and sensitized photoisomerization make a triplet mechanism in both cases probable.

Notizen: On the Chemistry of Acylthioureas. III. Synthesis of 1,3,5-Thiadiazine-2-thiones by the Reaction of Acylisothiocyanates with AminesIn course of synthesis of benzoyl-thioureas from benzoyl-isothiocyanate and sec. amines some new 6-amino-4-phenyl-1,3,5-thiadiazine-2-thione 5 are prepared and characterized chemically and spectroscopically.

Notizen: Cyanic Acid Esters. 25 The Reaction of Mercapto-N-heterocycles with Aryl CyanatesUnsaturated N-heterocycles containing a cyclic thio urea structure and aryl cyanates (molar ratio 1:2), react to form azolo(1,2-d) (1,2,4)thiadiazoles. This reaction has a wide scope concerning starting materials and gives good yields. Under the same conditions 2-thione-benzthiazolin is transformed to the corresponding disulfide. 4,5-Bis-mercaptomethylene-o-xylene and aryl cyanates give 2,3-dithia-6, 7-dimethyl-tetraline.

Notizen: Potentielle Psychopharmaka. IV. Synthese von Fluorindolen und verwandten Verbindungen

Notizen: Deactivation Behaviour of Arenes and Heteroarenes. XI. The Evidence of Radiationless Deactivating Excimers by Resonance-Energy TransferInvestigations of resonance-energy transfer in the systems of anthracene-/ and akridizinium ion/rhodamine B (BF4) show, that in the case of high concentrations of energy donors the amount of the relative fluorescence quantum yield is greater than one. This result demonstrates the existence of a further energy donor, the excimer. In the case of the N-methyl-acridinium ion/ rhodamine B (BF4)-system this fact cannot be observed, therefore a formation of excimers at high concentrations should be excluded. The existence (anthracene, akridizinium ion) and non-existence (N-methylacridinium ion) of excimers is in agreement with the ability of forming photodimers.

Notizen: Darzensreaktion mit chinoiden Systemen. Darstellung von Spirooxiran-2,2′-chrysenen aus Chrysenchinonen und Chrysooxazolen aus Chrysenchinoniminen oder Chrysenchinon-monoximenChrysenchinone reagieren mit substituierten Benzol- und Phenacylhalogeniden in Gegenwart von Basen zu Derivaten des Spiro-oxiran-2,2′-chrysens oder einer Methylendioxyverbindung,Chrysenchinonimin und -monoxim geben unter analogen Bedingungen Chrysooxazole.

Notizen: Reaktionen von Dimethyl-2,5-dihydroxy-3,6-dihydroterephthalat mit nucleophilen StickstoffverbindungenDimethyl-2,5-dihydroxy-3,6-dihydroterephthalat 1 wird durch basenkatalysierte Kondensation von Dimethylsuccinat dargestellt. Reaktionen von 1 mit einigen nucleophilen Stickstoffverbindungen werden untersucht.

Notizen: Zum Einfluß von Strukturparametern auf die Kinetik der Diazotierung und N-Nitrosierung aromatischer Amine

Notizen: Synthesis of the Shortened Analogue of the Insulin B Chain Terminally Substituted by Alanine in the Positions 4 and 27

Notizen: Projection microradiography was used to determine the density and orientation of the force transmitting structures, i.e., trabeculae and bone lying between approximately parallel vascular canals, within the bones of cat skulls. The organisation in the skulls was confirmed statistically for a total of ten cats. The results of the observations showed that within specific areas of the skull a high degree of structural orientation and an increased density of osseous structures was present. The distribution of these characters corresponded in contiguous bones such that a continuum of structural organisation was established between the alveolar region and the site of attachment of the temporalis and masseter muscles and the glenoid region.The patterns of force transmission during jaw closure were determined when a resistance was placed initially between the canines and then the carnassials. An analysis was first carried out on dry skulls using colophonium resin to determine the direction of the force distribution. The nature and the approximate magnitude of the forces were ascertained by replacing the resin with strain gauges. The basic similarities in the strain patterns recorded from the dry skulls and those from the ten anaesthetised cats in which strain gauges had been intra-vitally implanted, substantiated the recordings made on the dry skulls. Combination of the results from the three sets of experiments defined the patterns of force distribution in the cat skull during the closure of the mandible against a resistance. The results showed that: (1) the combined action of the temporalis and masseter muscles tended to reduce the overall strain in the skull bones, and that the deformations produced by the action of the masseter were greater than that exerted by the temporalis muscles; (2) during biting, whether the resistance was placed between the canines or carnassials, compressive forces predominated in the facial bones; (3) small movements observed between facial bones indicated the presence of a flexible component within the skull, thus allowing large forces to be exerted during biting without overstressing the facial bones; (4) the glenoid fossa is part of a force bearing joint; (5) forces generated during biting were resisted within the skull by forces of an opposite nature generated within the system, the incompressible nature of bone and by the effect of the soft tissues; (6) the nature and the magnitude of the strain altered when a resistance was placed at the canines and then at the carnassials; however, the pattern of force distribution within the skull remained the same; (7) there was a direct correspondence between the detailed structural organisation of the bones and the patterns of force distribution. This conclusion would appear to apply in general to mammalian skulls. The study also emphasises the importance, neglected hitherto, of carrying out a variety of experiments to determine the patterns of force distribution in bones.The Trajectorial Theory of bone organisation is discussed and, on the basis of the results obtained, a modified theory is proposed. This states that: the structural continuum is common to the compact and cancellous bone and comprises bony bars which are aligned in the optimum direction for the transmission of force to a region in the bone or bones where it is effectively resisted.

Notizen: The tarsi of all three pairs of legs of both sexes of Aedes aegypti (L.) bear spine sensilla, five types of hair sensilla, which are designated A, B, C1, C2 and C3, and campaniform sensilla. Type A and B hairs, spines, and cam-paniform sensilla are innervated by one neuron with a tubular body, a characteristic of cuticular mechanoreceptors. In particular the hairs and spines are tactile receptors and the campaniform sensilla are proprioceptors. The C1, C2, and C3 hair sensilla have the morphological features of contact chemoreceptors. Type C1 and C3 hairs are innervated by five and four neurons, respectively, which extend to the tip of the hair. Type C2 is innervated by five neurons, one of which terminates at the base of the hair in a tubular body while the remaining four extend to the tip of the hair. The role of the type C hairs in oviposition behavior, nectar feeding, and recognition of conspecific females is discussed. Presumed efferent neurosecretory fibers occur near the spine and hair sensilla.

Notizen: The micro-anatomy of the corpuscles of Stannius of the toadfish, Opsanus tau, an aglomerular marine teleost, has been studied by light and electron microscopy. The corpuscles are composed of extensively anastomosed cords of epithelial cells which maintain intimate contact with blood capillaries. Most of the epithelial cells contain acidophilic granules which also show a positive reaction with the periodic acid-Schiff technique and aldehyde fuchsin. On the basis of fine structural criteria, three cell types can be recognized. The granular cells contain abundant quantities of granular endoplasmic reticulum, ribosomes, Golgi apparatus with prosecretory granules, coated vesicles, polymorphic mitochondria with lamellar cristae, filaments, microtubules, a cilium, a variety of lysosome-like dense bodies, glycogen particles, lipid droplets, secretory granules and intranuclear lipid-like inclusions. One variety of agranular cell (type I) is characterized by the total absence of secretory granules, but it contains large amounts of granular endoplasmic reticulum and ribosomes, conspicuous profiles of Golgi apparatus, coated vesicles and sometimes an abundance of glycogen. Another variety of agranular cell (type II) has poorly developed cytoplasmic organelles. The perivascular space between the capillary and parenchyma contains connective tissue cells and abundant nerve fibers. The different types of epithelial cells observed in the corpuscles of Stannius of this fish may represent functional stages of the secretory cycle in a single cell type.

Notizen: The nervous system of the maldanid polychaetes Clymenella torquata (Leidy) and Euclymene oerstedi (Claparede) (= Caesicirrus neglectus [Arwidsson, '11-'12]) retains its primitive association with the epidermis. It shows only slight metamerism in the presence of larger collections of neurones opposite the parapodia and of larger nerves at the segmental boundaries. Multicellular giant fibers are present in the ventral nerve cord; giant neurones which show a characteristic pattern of distribution in each species are also present. The cerebral ganglia supply nerves to the prostomial wall, nuchal grooves and the wall of the buccal cavity, and a pair of large nerves from the circumpharyngeal connectives also appear to join the buccal system. The organs of special sense are the elongated prostomial nuchal grooves, and prostomial ocelli in Euclymene but not in Clymenella. Statocysts are absent.Four pairs of nephromixia are present. They lie in the aseptate anterior trunk, in chaetigers 5-9 of Clymenella, and 6-10 of Euclymene. The nephridiopores lie at the ventral ends of the neuropodia of chaetigers 6-9 and 7-10, respectively. Each nephromixium consists of coelomostome, tubule and contractile bladder. The wall of the tubule and bladder consists of both excretory and ciliated cells. Most of the cytoplasm of the latter forms a bounding layer at the outer surface. The cytoplasm of the excretory cells contains lipid material and appears to synthesize lipofuscin. The tips of the excretory cells swell, fill with granules, and break off in the form of vesicles which are periodically expelled in clouds from the nephridiopores. Glycogen is present, especially in the ciliated cells of the tubule and coelomostome.Granules of a lipoid nature accumulate in (or between) cells of the nephridia, epidermis, and some regions of the gut, and may be excretory. Lipid granules also appear to be synthesized by coelomocytes which eventually end up in masses in the ventrolateral coelomic cavities of the tail.The nephridia act as gonoducts, but show no seasonal variation in either size or histological structure.

Notizen: The ascophoran Pentapora foliacea was studied from epoxy sections of skeletal and soft (hard-soft) tissues. The basal wall is double, indicating the colony grew as two independent layers, back to back. The structure of the vertical walls and interzooidal communication organs indicates that zooids were budded in the usual way as in most encrusting cheilostomes. Secondary layers of the frontal wall are of acicular aragonite. The ovicell develops as a flattened cuticular bladder in early ontogeny; the aragonitic layer of the frontal wall later engulfs it. A median vesicle, an evagination of the vestibular wall, is present but the eggs may be supplied with sufficient yolk to nurture the embryo. The overall ovicell structure is similar to that of hyperstomial ovicells in other cheilostomes.

Notizen: This investigation describes the pre-natal morphogenesis of the type I pneumocyte subsequent to its differentiation from pulmonary epithelium. Cells lining subpleural alveolar septa were photographed from serial sections with the electron microscope, and a three-dimensional representation of each cell was obtained by transferring the contours of the cell membranes from montages to transparent plastic sheets which were then spaced to scale and stacked. The results of this study indicate that: The nascent blood-air barrier of a 50-day reconstructed cell was twice as thick as the average definitive barrier; definitive barrier thickness was observed in some areas in a 63-day reconstructed cell; the amorphous component of elastic tissue which appears peripherally in septal connective tissue during pre-natal morphogenesis may be directly juxtaposed to the basal lamina of the alveolar epithelium; the orientation of the cell junction between a pneumocyte and its neighboring cells, as observed in sections of alveolar septa, changes as the contour of the pneumocyte changes from simple abutment to overlapping patterns.

Notizen: The fine structure of the mid-gut musculature of the desert locust, Schistocerca gregaria is described and compared with that of the visceral muscles of other species. The gross morphology and fine structure of the nervous system which supplies the mid-gut muscle fibres is described.

Notizen: The integument of Paranthessius anemoniae has been studied with light and electron microscopy. A cuticle with clearly defined epicuticular, exocuticular and endocuticular regions overlies a cellular hypodermal layer. The distribution of carbohydrate, lipid and protein components of the cuticle were demonstrated histochemically. Parabolic striations in oblique sections of cuticle suggest that its molecular architecture fits a “twisted sheet” theory proposed for other species.Arthrodial membranes at body and limb joints have a homogeneous structure, lacking exocuticle and endocuticle. Subcuticular glands appear to secrete substances thought to be responsible for the immunity which Paranthessius seems to have to the nematocysts of its host. Small hairs, situated in cuticular cups which occur over the dorsal body surface are considered to function as rheoreceptors.

Notizen: The larval epithelium of the sea urchin, Lytechinus pictus, consists of squamous cells and bands of columnar epithelial cells bearing cilia. During metamorphosis this tissue undergoes a series of rapid, complex changes. Through the scanning and transmission electron microscope, we describe and analyse these changes. The changes can be divided into three steps. (1) The larval arms bend away from the left side of the larva, exposing the urchin rudiment. Cells which are identical to smooth muscle cells are in a position to bring about this bending. (2) The squamous epithelial cells assume a cuboidal shape. This change in shape results in the collapse of the larval epithelium onto the presumptive aboral surface. These cells possess a subapical band of microfilaments. The cellular shape change but not the bending of the arms is reversibly inhibited by Cytochalasin B. These observations suggest a mechanism for this change. (3) The former lining of the vestibule of the urchin rudiment comes to lie over the collapsed larval tissue and forms the adult epithelium. At this point, after only one hour, the larva has assumed the external shape of an adult sea urchin.

Notizen: The mucous gland of the red-spotted newt, Notophthalamus viridescens viridescens, Rafinesque was examined by histochemical and ultrastructural techniques and its cytological responses to various hormonal conditions were studied. Its secretory epithelial cells produce and release in merocrine fashion a neutral, unsulphated mucosubstance. The secretory epithelium is bounded peripherally by a thin, but apparent non-functional, myo-epithelium. The duct of this mucous gland consists of a single keratinized tubular cell that extends from the neck region of the gland to the surface of the epidermis.Mucous secretion is absent or greatly reduced on the skins of newts maintained under laboratory conditions for a few weeks but reappears after injection of ovine prolactin. Mucous glands in laboratory conditioned animals show a 4-fold increase in volume brought about by the engorgement of their epithelial cells with secretory granules. Ovine prolactin reduces the volume of the glands to unconditioned levels with a corresponding reduction in granular content, suggesting that prolactin functions in the release of the granules. This view is reinforced by the findings that autotransplantation of the pituitary gland prevents the conditioning effect and that glandular volume increases in auto-transplanted animals given ergocornine. Granular accumulation begins also in hypophysectomized newts but ceases after a week, indicating the need for some hypophyseal factor in the synthesis as well as the release of the granules. Ovine prolactin restores mucous glands of hypophysectomized newts to the unconditioned state. Contrary to earlier findings, ovine prolactin induces a reduction in the volume of the mucous gland in thyroidectomized newts.

Notizen: The process of coelomic pouch formation in Pisaster ochraceus was studied with light microscopy, transmission and scanning electron microscopy and time-lapse cinemicrography as well as with the drug cytochalasin B. As in most asteroids, the paired coelomic pouches of Pisaster ochraceus are formed from outpocketing of the archenteron.Arrays of 50 Å microfilaments are found in the presumptive coelomic pouch cells at the apex of the archenteron as well as in the filopodia of the mesenchyme cells. Both cell types undergo active movements throughout the entire process. Treatment of embryos with cytochalasin B (CCB) during coelomic pouch formation results in the loss of cell movements and the regression of the coelomic pouches; this is accompanied by the loss of microfilament arrays in both cell types. Cell movements and microfilament arrays reappear on removal of CCB and coelomic pouch formation resumes.Our evidence suggests that the microfilaments in the presumptive coelomic pouch cells provide the main force for the outpocketing movement. The major role of the microfilament arrays in the filopodia of the mesenchyme cells associated with the coelomic pouches is to determine the definitive shape and location of the pouches.

Notizen: Morphological changes of the ovary of the Chinese cobra, Naja naja, throughout the annual reproductive cycle are described. A single clutch of between 6 and 22 eggs is produced in late June. From July to the following April the ovary remains quiescent and contains small previtellogenic, hydration stage follicles. The growth of an ovarian follicle from a primary oocyte to maturation and ovulation is estimated to take three years. The histology of the germinal epithelium and the follicular granulosa shows seasonal changes correlated with the growth of the oocyte. During the quiescent period, the germinal epithelium lacks mitotic activity, but during April, when yolk deposition and rapid growth of the preovulatory follicles take place, the germinal epithelium shows intense mitotic activity. The growth of the smallest hydration stage follicles, and the occurrence of cytoplasmic bridges between the pyriform cells of the granulosa and the developing oocyte, also appear to increase during this period. The possible function of the pyriform cell is discussed and the literature on the origin and fate of these cells in the squamate ovary is reviewed. Postovulatory follicles (corpora lutea) and two types of atresia are described and compared with what is known of these structures in other reptiles.