Addition products of dimethyl acetylenedicarboxylate to thioureas- Studies on 2-(p-bromophenyl) imino-3-methyl-5-carbomethoxymethylidenethiazolidin-(4)-one

Abstract

N-(p-bromophenyl)-N'-methylthiourea (1) undergoes addition to acetylenedicarboxylic acid (3) and its dimethyl ester (4) to form 2-(p-bromophenyl) imino-3-methyl-5-carboxymethylidenethiazolidin-(4)-one (5) and its methyl ester (6) respectively. Alkaline hydrolysis of (6) leads to a mixture of (5) and 2-(p-bromophenyl) imino-3,4-dihydro-3-methyl-4-oxo-2H (1,3)-thiazine-6-carboxylic acid (7). Several reactions of (5) and (7) are described. The structures of (5) and (7) are established by x-ray crystallographic and ¹³CNMR studies.