ISSN:0165-0513    

DOI:10.1002/recl.19901090402

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractCondensation of 2,3: 5,6‐di‐O‐isopropylidene‐D‐mannopyranose with (ethoxycarbonylmethylene)triphenylphosphorane afforded the expected Wittig product. Reaction of the latter with chlorotrimethylsilane followed by methyl methanethiosulfate, in the presence of I. DA and after removal of the trimethylsilyl and unmasking of the dimethyl thioketal function, gave the title compound in a good over

ISSN:0165-0513    

DOI:10.1002/recl.19901090403

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractAn asymmetric synthesis of the six‐carbon α‐amino acids (ϵ‐13C)‐L‐α‐aminoadipic acid and various isotopomers of L‐lysine is described. The synthesis is based on a general method starting from the bis‐lactim ether of cyclo(D‐Val‐Gly) and simple labelled reagents like K13CN, K13C15N,13CH3CN and LiAl2H4. Using this route (ϵ‐13C)‐L‐α‐aminoadipic acid was prepared in 31% yield based on the labelled potassium cyanide. Five different isotopomers of L‐lysine were prepared in high overall yield (45% based on the labelled starting compound): (ϵ‐13C)‐L‐lysine, (ϵ‐13C,ϵ‐15N)‐L‐lysine, (δ‐13C)‐L‐lysine, (ϵ‐2H2)‐L‐lysine and (ϵ‐13C,ϵ‐2H2)‐L‐lysine. The isotopomers were characterized using various spectroscopic techniques, e.g.,1H NMR,2H NMR,13C NMR,15N NMR and mass spectrometry. The 31.2‐ppm and the 27.6‐ppm peak in the13C NMR spectrum of lysine could be unambiguously assigned to the β‐ and δ‐c

ISSN:0165-0513    

DOI:10.1002/recl.19901090404

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractL‐(3a‐13C)‐ And L‐(6‐13C)tryptophan have been synthesized from simple labelled compounds via a single reaction scheme based on the conversion of 1,3‐cyclohexanedione into indole. The labelled indoles have been converted in one step into the corresponding L‐tryptophans using transformedEscherichia colicells with large amounts of the enzyme, tryptophan synthetase. The same reaction scheme has been used for the synthesis of 4‐ and 7‐indolol. These hydroxyindoles together with 5‐indolol have been converted into 4‐, 7‐ and 5‐hydroxy‐L‐tryptophan, respectively, using theEscherichia colicells. The latter compound is the immediate precursor of the neurotransmitter, serotonin. It appears that 7‐indolol is the only indole derivative which is converted faster than unsubstituted indole by the enzyme, tryptophan synthetase. With the preparation of L‐(3a‐13C)‐ and L‐(6‐13C)tryptophan, we have completed the series of indoles and L‐tryptophans with a stable isotope (13C,15N or2H) in the aromatic ring. In this paper, we also discuss the NMR parameters

ISSN:0165-0513    

DOI:10.1002/recl.19901090405

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractAn N‐alkylnicotinamidium salt has been linked covalently to Cys 25 of papain and thereafter reduced to the 1,4‐dihydro form. Reactions of this material have been exami

ISSN:0165-0513    

DOI:10.1002/recl.19901090406

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractPhosphino‐stabilized allyl anions are formed by deprotonation of phosphinopropenes with alkyllithium. A double deprotonation of 2‐diphenylphosphinomethyl‐3‐diphenylphosphinopropene leads to interesting phosphino‐stabilized trimethylenemethane dianions. Alkylation with methyl iodide occurs at a carbon atom and not at a phosphor

ISSN:0165-0513    

DOI:10.1002/recl.19901090407

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractThe title compound is easily lithiated at its NMe groups by alkyllithiums dissolved in alkanes.

ISSN:0165-0513    

DOI:10.1002/recl.19901090408

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19901090409

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19901090411

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19901090413

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY