A New General Approach to Enantiomerically Pure Cyclic and Open??Chain (R)??and (S)?螃?, α??Disubstituted α??Amino Acids

…, P Schönholzer, K Müller, H Heimgartner…

Index: Obrecht; Spiegler; Schonholzer; Muller; Heimgartner; Stierli Helvetica Chimica Acta, 1992 , vol. 75, # 5 p. 1666 - 1696

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Citation Number: 89

Abstract

Abstract A wide range of cyclic and open-chain α, α-disubstituted α-amino acids 1a-p were prepared. The racemic N-acylated α, α-disubstituted amino acids were resolved by coupling to chiral amines 15-18 derived from (S)-phenylalanine to form diastereoisomers 19/20 or 21/22 that could be separated by crystallization and/or flash chromatography on silica gel (Scheme 3). Selective cleavage via the 1, 3-oxazol-5 (4H)-ones 10a-p gave the ...