Abstract
Title compounds were prepared in 20-72% yields from the S-aklylation of pyridinium 1- [3-ethoxycarbonyl-1-[(methylthio)thiocarbonyl]]allylides with some alkyl halides, followed by the treatment of the resulting pyridinium salts with a base and then a dehydrogenating agent. In part of these reactions novel heterocycles, ethyl 1-cyano-3-(methylthio)thieno[3, 4-b]indolizine-9-carboxylates, were also formed. The oxidation of the title compounds with m-chloroperbenzoic acid gave the corresponding sulfoxides in moderate to good yields, which smoothly underwent Pummerer reactions on treatment with acetic anhydride. The bromination of the 3-vinyl group in the title compounds, followed by treatment of the resulting dibromo adducts with a base afforded ethyl 2-bromo-3-[2-(methylthio)indolizin-3-yl]acrylates, 3-[1-cyano-2-(methylthio)indolizin-3-yl]propiolates, and ethyl thieno[2, 3-b]indolizine-2-carboxylate depending upon the substrate used.
