摘要:

AbstractA series ofcis‐ andtrans‐dichloro(benzylamine) (chiral olefin) platinum(II) complexes, containing (Z) and (E) isomers of the internal chiral olefins R‐CH=CH‐R', has been prepared by ethylene displacement from the corresponding ethylene containing complexes. The particular stereochemical features of the complexes allow one to interpret the CD on the basis of the individual contributions coming from the chiral centres already present in the free olefin and from the chiral centres formed in the complexation of the double bond. Evidence is reported showing that the aforementioned contributions are additive and that the chiral centre(s) bound to the metal dominates the CD at about 400 nm, its chirality type being reflected in the sign and its chirality prevalence in the

ISSN:0021-2148    

DOI:10.1002/ijch.197600012

出版商:WILEY‐VCH Verlag    

年代:1976

数据来源: WILEY

摘要:

AbstractWe have synthetized an optically active macromolecular chromatographic packing from cross‐linked polyacrylamide grafted with an optically active α‐amino acid. This packing, in the form of small beads, slightly swells in water. Its granularity, porosity and rigidity are suitable for high pressure liquid chromatography. Such packings, complexed by a metallic ion, are efficient for the resolution of many underivatized racemic α‐amino acids by elution with water. As an example, on one of these packings, containing Cu++ions, enantiomers of valine, threonine, isoleucine, serine, phenylalanine, tyrosine, tryptophan, and asparagine are completely resolved in less than o

ISSN:0021-2148    

DOI:10.1002/ijch.197600013

出版商:WILEY‐VCH Verlag    

年代:1976

数据来源: WILEY

摘要:

AbstractSeveral classes of organotin compounds are configurationally stable within the NMR time‐scale and are even optically stable for weeks. Optically active tetraorganotin compounds, triorganotin hydrides and an optically active (triorganogermyl)triorganotin compound have been synthesized. Two reactions transforming optically active triorganotin hydrides into optically active tetraorganotin compounds are describe

ISSN:0021-2148    

DOI:10.1002/ijch.197600014

出版商:WILEY‐VCH Verlag    

年代:1976

数据来源: WILEY

摘要:

AbstractAsymmetric photocyclization of N‐methyl N‐aryl enamines by circularly polarized light gives several optically active N‐methyl dihydroindoles. In the synthesis of N‐methyl 2‐phenyl dihydroindole, the optical yield was evaluated to be 0.20%, which is the same order of magnitude as in the asymmetric synthesis of helicenes. The mechanisms of these reactions are

ISSN:0021-2148    

DOI:10.1002/ijch.197600015

出版商:WILEY‐VCH Verlag    

年代:1976

数据来源: WILEY

摘要:

AbstractExamples of quasi‐racemic clathrates involving resolved Dianin's compound and some of its analogues are describe

ISSN:0021-2148    

DOI:10.1002/ijch.197600016

出版商:WILEY‐VCH Verlag    

年代:1976

数据来源: WILEY

摘要:

AbstractThe heterogeneous reduction of various water‐insoluble ketones (i.e., alkyl phenyl ketones and alkyl methyl ketones) was carried out with an aqueous NaBH4solution in the presence of lecithin. It was found that the rate of the reduction reaction from ketone to carbinol was enhanced by lecithin, which is known as an optically active and zwitterionic surface active substance. Furthermore, when the unsymmetric ketones were reduced in this system the carbinols obtained were found to be optically active, though their optical yields were low. From the above results, it was concluded that the reduction reaction proceeds mainly at the micelle–water interf

ISSN:0021-2148    

DOI:10.1002/ijch.197600017

出版商:WILEY‐VCH Verlag    

年代:1976

数据来源: WILEY

摘要:

AbstractThe history of experiments bearing on the origin of optical activity in nature by parity non‐conservation during the β‐decay of radioactive isotopes is briefly reviewed. Following this, we present a more detailed description of our recent published and unpublished data and calculations regarding the generation of optical activity in DL‐leucine by means of artificially produced longitudinally polarized electrons from a linear accel

ISSN:0021-2148    

DOI:10.1002/ijch.197600018

出版商:WILEY‐VCH Verlag    

年代:1976

数据来源: WILEY

摘要:

AbstractA recently developed gas chromatographic method was used to determine quantitatively the enantiomeric composition as well as the amounts of accompanying impurities of an olefin, thus allowing calculation of its specific rotation. Applying this procedure it was found that the specific rotation of (+)‐3‐methylcyclopentene is more than double that reported in the literature, namely [α]D20= + 174.5°

ISSN:0021-2148    

DOI:10.1002/ijch.197600019

出版商:WILEY‐VCH Verlag    

年代:1976

数据来源: WILEY

摘要:

AbstractThe configurations of the trishomobarrelene and trishomobullvalene bridgehead derivatives1b–1g, 2a–2eand2ghave been correlated with the absolute configuration of1cas determined by X‐ray crystallography, on the basis of their circular dichroisms, especially those of the carboxylic acids1band2b. All derivatives prepared from the dextrorotatory (+)‐1band (+)‐2bresemble dextroverse propellers when looked upon from the substituted side. Attempts to prepare the new chiral trioxa‐[D3]‐trishomocubane 7 in optically active form, have failed so far. It is predicted, however, that (−)‐7 should have the same (all‐S)‐configuration as the levorotatory parent hydrocarbon (S)‐[D3]‐trishomocubane. In addition, a synthetic approach to two more C3‐symmetric propeller molecules, the hexahydrophenalene13and its trisho

ISSN:0021-2148    

DOI:10.1002/ijch.197600020

出版商:WILEY‐VCH Verlag    

年代:1976

数据来源: WILEY

摘要:

AbstractEvidence for some emission from the first excited singlet state of tris‐(2,2′‐bipyridine) ruthenium (II) bromide is presented based on circular dichroism, circular polarization of luminescence and fluorescence decay measurements. The anisotropy factors in absorption and emission assume very similar values in the wavelength region where these two spectra overlap. Moreover, the two anisotropy factors change markedly in this wavelength range indicating the existence of a second emission band at the short wavelength edge of the main phosphorescence band of the chelate. This observation is further supported by fluorescence decay measurements which reveal biexponential decay kinetics with a fast decaying component at the short wavelength edge of the emi

ISSN:0021-2148    

DOI:10.1002/ijch.197600021

出版商:WILEY‐VCH Verlag    

年代:1976

数据来源: WILEY