SYNTHESIS OF ACYLAMIDO KETENE DITHIOACETALS AND OXO-4,5-DIHYDROBENZO[F]-1,4-THIAZEPINE-DERIVATIVES BY DITHIOCARBOXYLATION OF ALPHA-AZA-C-NUCLEOPHILES

N-acceptor methyl substituted 2,2,N-trimethyl-propionamides (1 acc-gro up = p-MeOC6H4CO-, 2 acc-group = COOMe) afford in the procedure of dit hiocarboxylation 3,3-[bis(alkylthio)]-prop-2-ene-1-ones 4a-c and methy l 3,3-[bis(alkylthio)]-acrylates 5a-c, respectively. 2-Chloro- or 2,4- dichloro-N-cyanomethyl-N-methyl-benzamide 3a,b form in the reaction wi th carbon disulfide at lower temperature 3,3-bis(methylthio)-acrylonit riles 7a,b whereas 4,5-dihydrobenzo[f]-1,4-thiazepine-3-carbonitriles 8a-c are obtained at higher temperatures.