摘要:

AbstractESR. and ENDOR. studies are reported for the radical anions of 1,2‐diphenylcyclopentene (3) and its di(pe+deuteriophenyl)‐derivative (3‐D10). Comparison of the coupling constants of the phenyl protons in3\documentclass{article}\pagestyle{empty}\begin{document}$ ^{\ominus \atop \dot{}} $\end{document}. with the analogous values for the radical anions of 1,2‐diphenyl substituted cyclopropene (1) and cyclobutene (2) reveals regular changes in the sequence1\documentclass{article}\pagestyle{empty}\begin{document}$ ^{\ominus \atop \dot{}} $\end{document},2\documentclass{article}\pagestyle{empty}\begin{document}$ ^{\ominus \atop \dot{}} $\end{document},3\documentclass{article}\pagestyle{empty}\begin{document}$ ^{\ominus \atop \dot{}} $\end{document}, which are caused by an increasing twist of the phenyl groups about the C(1), C(1′)‐ and C(2), C(1″)‐bonds linking them to the ethylene fragment. Such a twist is shown to be also responsible for the large difference in the coupling constants of the methylene β‐protons in3\documentclass{article}\pagestyle{empty}\begin{document}$ ^{\ominus \atop \dot{}} $\end{document}. (0.659 and 0.293 mT). It is suggested that ‐ in order to minimize the losses caused by this twist in the π‐delocalization energy ‐ the 2 pz‐axes at the centres 1 and 2 deviate from a perpendicular orientation to the mean plane of the cyclopentene ring. A deviation by 19° from such an orientation is required to account for the observed β‐proton coupling constants in terms of their conventional cos2‐de

ISSN:0018-019X    

DOI:10.1002/hlca.19790620802

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

AbstractThe crystal structure of the antibiotic hedamycin (1) has been solved by direct method and refined by least squares techniques to R = 0.091 for 2289 of 2643 independent reflexions. Crystals of C41H50N2O11are orthorhombic, space group P212121with lattice parametersa= 24.239 (12),b= 21.440 (10),c= 7.369 (4) Å, Z = 4. The structural features of hedamycin derived earlier by chemical and spectroscopical means are confirmed. Optical rotation and circular dichroism indicate that hedamycin (1) has the absolute configuration of the related antibiotic kidamycin (3). The conformation of ring F is a chair form with the aryl substituent almost axial. The bioxirane part of the antibiotic is in a synclinal conformation

ISSN:0018-019X    

DOI:10.1002/hlca.19790620803

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

Synthesis and Chirality of (5R, 6R)‐5,6‐Dihydro‐β, ψ‐carotene‐5,6‐diol, (5R, 6R, 6′R)‐5,6‐Dihydro‐β, ε‐carotene‐5,6‐diol, (5S, 6R)‐5,6‐Epoxy‐5,6‐dihydro‐β,ψ‐carotene and (5S, 6R, 6′R)‐5,6‐Epoxy‐5,6‐dihydro‐β,ε‐caroteneWittig‐condensation of optically active azafrinal (1) with the phosphoranes3and6derived from all‐(E)‐ψ‐ionol (2) and (+)‐(R)‐α‐ionol (5) leads to the crystalline and optically active carotenoid diols4and7, respectively. The latter behave much more like carotene hydrocarbons despite the presence of two hydroxylfunctions. Conversion to the optically active epoxides8and9, respectively, is smoothly achieved by reaction with the sulfurane reagent ofMartin[3]. These syntheses establish the absolu

ISSN:0018-019X    

DOI:10.1002/hlca.19790620804

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

Sorelline and Hobartine, Two New Indole Alkaloids fromAristotelia peduncularis(LABILL.) HOOK. F.FromAristotelia peduncularis(LABILL.) HOOK. F. two new indole alkaloids, sorelline (1) and hobartine (2), have been isolated. Their structures were elucidated on the basis of spectroscopic data (the formulae represent their relative configurations). The alkaloids1and2have closely related structures with a monosubstituted indole moiety and an unrearranged monoterpene unit in the aliphatic part.

ISSN:0018-019X    

DOI:10.1002/hlca.19790620805

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

Synthesis of 4‐Trichlorosilylmethylbenzonitrile and 4‐(2‐Trichlorosilylethyl)pyridine for Surface Modification of Tin DioxideWe describe the synthesis of 4‐(trichlorosilylmethyl)benzonitrile and 4‐(2‐trichlorosilylethyl)pyridine, starting from 4‐(bromomethyl)benzonitrile and trichlorosilane or vinylpyridine and trichlorosilane. Trimethoxysilanes are obtained by reaction of the trichlorosilyl compounds with methyl orthoformate. 4‐(Trichlorosilylmethyl)benzonitrile and 4‐(2‐trichlorosilylethyl)pyridine are used to modify the sur

ISSN:0018-019X    

DOI:10.1002/hlca.19790620806

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

AbstractThe structures of the main carotenoid pigments from the mutant 1‐207 ofRhizobium lupiniwere elucidated by spectroscopic techniques (UV./VIS., CD., 270 MHz1H‐NMR., and MS.). Ten carotenoids were identified, namely β,β‐carotene (1), β,β‐caroten‐4‐one (echinenone,2), β,β‐carotene‐4,4′‐dione (canthaxanthin,3), (3S)‐3‐hydroxy‐β,β‐caroten‐4‐one ((3S)‐3‐hydroxyechinenone,4), (2R, 3R)‐β,β‐carotene‐2,3‐diol (5), (3S)‐3‐hydroxy‐β,β‐carotene‐4,4′‐dione ((3S)‐adonirubin,6), (2R, 3S)‐2,3‐dihydroxy‐β,β‐caroten‐4‐one (7), (2R, 3S)‐2,3‐dihydroxy‐β,β‐caroten‐4,4′‐dione (8), (2R, 3S, 2′R, 3′R)‐2,3,2′,3′‐tetrahydroxy‐β,β‐caroten‐4‐one (9) and the corresponding (2R, 3S, 2′R, 3′S)‐4,4′‐dione (10). Structures5, 7, 8and10have not been reported before. From the observed carotenoid pa

ISSN:0018-019X    

DOI:10.1002/hlca.19790620807

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

Separation of the Diastereomers (6R) and (6S)‐5,6,7,8‐Tetrahydro‐L‐neopterinThe mixture of the diastereomers of the pentaacetylderivative IV of (6RS)‐5,6,7,8‐tetrahydro‐L‐neopterins could be separated by fractional crystallisation in methanol into the diastereomers IV A and IV B. Hydrolysis with hydrochloric acid gives the pure, diastereomeric, (6R)‐ and (6S)‐5,6,7,8‐te

ISSN:0018-019X    

DOI:10.1002/hlca.19790620808

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

Abstract10, 10, 12‐Trimethyl‐3,4‐benzo‐1,6‐dithia‐9,13‐diazacyclopentadecen‐dihydrochloride (LH 22+,2) and its Ni2+complex were synthesized and their reactivity studied. The formation kinetics of2with Cu2+were found to be a second order reaction between Cu2+or CuACO+and the monoprotonated form of the ligand LH+. The rate constantk CuLH= 29M−1S−1is 105–106times smaller than those of monoprotonated tetraazamacrocycles either because of second bond formation or because of a strong electrostatic interaction between the positive charges of the Cu2+and the ammonium group. The metal‐metal exchange between NiL+and Cu2+was also investigated. The reaction is independent of [Cu2+] and has the same rate and activation parameters as the dissociation of NiL2+. In contrast to open chain ligands, no mixed complex CuNiL4+a

ISSN:0018-019X    

DOI:10.1002/hlca.19790620809

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

AbstractThe radical anions of the following substituted [2.2]paracyclophanes have been characterized by ESR. and ENDOR. spectroscopy: 4, 16‐dicyano‐ (o‐2), 4, 12‐dicyano‐ (p‐2), 4,5,12,13‐tetracyano‐ (3) and 4,5,12,13‐tetrakis (alkoxycarbonyl)‐ [2.2]paracyclophanes (4‐R, where R = Me, Et,iPr ortBu is the ester alkyl group); 4,5‐bis(methoxycarbonyl)[2.2]paracyclophane‐12, 13‐dicarboxylic anhydride (5); [2.2]paracyclophane‐4,5:12, 13‐tetracarboxylic bisanhydride (6) and bisimides (7‐R, where R = H, D, Me or Ph is the substituent at the imideN‐atom). Comparison of the hyperfine data for these radical anions with those for analogously substituted derivatives of benzene indicates that the most prominent coupling constants are approximately halved on passing from the latter to the former. Lowering of the symmetry, as a consequence of ion pairing, has been observed for the radical anions4‐iPr\documentclass{article}\pagestyle{empty}\begin{document}$^{\ominus \atop \dot{}}$\end{document}and4‐tBu\documentclass{article}\pagestyle{empty}\begin{document}$^{\ominus \atop \dot{}}$\end{document}associated with the counterionK⊕ in 1,2‐dimethoxyethane at 183 K, but not for4‐Me\documentclass{article}\pagestyle{empty}\begin{document}$^{\ominus \atop \dot{}}$\end{document}and4‐Et\documentclass{article}\pagestyle{empty}\begin{document}$^{\ominus \atop \dot{}}$\end{document}under the same conditions. This result suggests that the migration ofK⊕ between the preferred sited in two equivalent ion pairs is slowed down by the steric hindra

ISSN:0018-019X    

DOI:10.1002/hlca.19790620810

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY

摘要:

Separation of the Diastereomers (6R)‐ and (6S)‐5,6,7,8‐Tetrahydro‐L‐biopterinThe mixture of the diastereomers of the tetraacetylderivative IV of (6RS)‐5,6,7,8‐tetrahydro‐L‐biopterin could be separated by fractional crystallisation in methanol into the diastereomers IV A and IV B. Hydrolysis with hydrochloric acid gives the pure, diastereomeric, (6R)‐ and (6S)‐5,6,7,8‐

ISSN:0018-019X    

DOI:10.1002/hlca.19790620811

出版商:WILEY‐VCH Verlag GmbH    

年代:1979

数据来源: WILEY