Studies of organosulfur compounds - part vi

: Syntheses of a hitherto unknown 4H-thieno[3,2-c]-' thiopyran and its 4-oxo derivative from a substituted dihydrothiopyranone by Vilsmeier-Haack reaction followed by condensation with methyl mercaptoacetate under basic conditions is reported herein. This communication highlights also the involvement of an unusual oxidation step leading to the formation of the 4-oxo derivative (5). © 1990, Taylor & Francis Group, LLC. All rights reserved.