Chiral (Z)-alpha,beta-didehydroamino acid derivatives from a new chiral glycine equivalent with a 1,2,3,6-tetrahydropyrazin-2-one structure: applications to the synthesis of 1-aminocyclopropanecarboxylic acids and bicyclic alpha-amino acids

The new chiral glycine equivalent 9, easily obtained from(+)-alpha-aminoiso valerophenone and glycine, afforded chiral (Z)-alpha,beta-didehydroamino ac id (DDAA) derivatives 13 and 14 with a 1,2,3,6-tetrahydropyrazin-2-one stru cture. Compounds 13 and 14 were synthesised by reaction of 9 with Eschenmos er's salt and by condensation reactions with aldehydes or acetone under PTC conditions, respectively. The diastereoselective cyclopropanation of 14, f ollowed by hydrolysis, furnished (-)-allo-norcoronamic acid with high ee, w hilst diastereoselective Diels-Alder reaction of dienophile 13 and cyclopen tadiene afforded, after double bond hydrogenation and hydrolysis, (-)-2-ami nonorbornane-2-carboxylic acid. (C) 2000 Elsevier Science Ltd. All rights r eserved.