The synthesis of novel heterocyclic substituted α-amino acids; further exploitation of α-amino acid alkynyl ketones as reactive substrates
作者:Robert M. Adlington、Jack E. Baldwin、David Catterick、Gareth J. Pritchard、Lam T. Tang
DOI:10.1039/b001825m
日期:——
A series of novel non-proteinogenic heterocyclic substituted α-amino acids derived from L-aspartic acid have been synthesised using the alkynyl ketone functionality as a versatile building block. Condensation of (S)-2-tert-butoxycarbonylamino-4-oxohex-5-ynoic acid tert-butyl ester 4 with enamines 5, 6, phenylhydrazine, hydroxylamine and phenyl azide has led to the generation of pyridines 9, 10, pyrazolines 11a/b, isoxazoles 12a/b, and triazole 13, respectively in moderate to excellent yields. Acid deprotection of the initial adducts afforded the desired heterocyclic substituted α-amino acids as their TFA salts or in the form of the zwitterions themselves after ion-exchange chromatography. The enantiomeric purity of a representative selection of these products were greater than 98% ee as verified by derivatisation to the corresponding Mosherâs amides and subsequent 19F NMR spectroscopy.
The synthesis of novel heterocyclic substituted α-amino acids; further exploitation of α-amino acid alkynyl ketones
作者:Robert M. Adlington、Jack E. Baldwin、David Catterick、Gareth J. Pritchard、Lam T. Tang
DOI:10.1039/a909720a
日期:——
A range of novel heterocyclic substituted α-amino acids has been synthesised by cyclocondensations of (S)-2-tert-butoxycarbonylamino-4-oxohex-5-ynoic acid tert-butyl ester with enamines, phenylhydrazine, hydroxylamine and phenyl azide.