A synthesis of functionalized arylthio-acrylates, benzo[b][1,4]thiazines and benzo[4,5]thiazolo[3,2-a]azepines from 2-methylbenzothiazole and acetylenic esters in aqueous media.

Alkyl (Z)-3-((2-(N-((E)-3-methoxy-3-oxoprop-1-en-1-yl)acetamido)phenyl)thio)acrylates are obtained from the reaction between 2-methylbenzothiazole and alkyl propiolates in 70% aqueous alcohol, in moderate yields. When dialkyl acetylenedicarboxylates were used under similar conditions, tetra-alkyl 9,10-dihydrobenzo[4,5]thiazolo[3,2-a]azepine-7,8,9,10-tetracarboxylates, together with dialkyl 4-acetyl-3,4-dihydro-2H-benzo[b][1,4]thiazine-2,3-dicarboxylates were obtained in about 4:1 ratios. The stereochemistry of these products has been confirmed by X-ray diffraction.