A SIMPLE SYNTHESIS OF ALPHA,BETA-UNSATURATED GAMMA-AMINOBUTYRIC-ACID (GABA) DERIVATIVES FROM ENAMINES

Bromination of enamines 3b-g at -78 degrees C and subsequent treatment of the resulting iminium salts 4b-g with excess tert-butyl lithioacet ate leads to tert-butyl 4-(N,N-dialkylamino)carboxylates 9b-g in good to very good yields. Ester cleavage of the dibenzylamino derivative 9d with trifluoroacetic acid yields the corresponding acid 10. Subsequen t catalytic hydrogenation of 10 leads to the fully deprotected 4-amino -4-methylpentanoic acid (12) in high yield.