AMINO ACIDS IN THE SYNTHESIS OF HETEROCYCLIC SYSTEMS - SYNTHESIS OF GAMMA-(5-(1,2,4-TRIAZINYLIDENE))-ALPHA,BETA-DEHYDRO-ALPHA-AMINO ACID DERIVATIVES AND 6H-PYRIDO[1,2-D][1,2,4]TRIAZIN-6-ONES

摘要

5-(1,2,4-Triazinyl) substituted enamines 3 react with 5(4H)-oxazolones 4 in acetic anhydride to give acetylated products 5, while in toluene-acetic acid mixture nonacetylated products 9 are formed. Both types of products were isolated as (E,Z) mixtures. Compounds 5 and 9 rearrange into 6H-pyrido[1,2-d]-[1,2,4]triazin-6-ones 12 by heating in formic acid or in xylene, respectively. Compounds 5 are transformed in the presence of nucleophiles, such as sodium alkoxides or sodium amides via anionic form 10 into corresponding esters 13 and amides 14 of gamma-(5-(1,2,4-triazinylidene)) substituted derivatives of alpha-amino-2-butenoic acid, which exist in 2-(Z),4-(Z) form. [References: 19]