A new and high efficient one-pot stereoselective synthesis of alkyl E-2-(2-imino-4-oxo-1,3-thiazolan-5-yliden) acetates

Thiourea reacts with dialkyl acetylenedicarboxylates in acetone to form 1:1 adducts, which undergo a cyclization reaction to produce alkyl E-2-(2-imino-4-oxo-1,3-thiazolan-5-yliden)acetates, in fairly high yields. Under the same conditions, thioacetamide reacts with dimethyl acetylenedicarboxylate to form dimethyl E-2-(ethanimidoylsulfanyl)-2-butenedioate. The products are stable crystaline solids whose structures are supported by IR, MS, (1) H NMR, C-13 NMR spectroscopy, and elemental analyses.