A Novel Approach to the Synthesis of Highly Functionalized Thiophenes Using Isocyanides Catalyzed Reaction of Acetylenic Esters with 3-Mercapto-2-Butanone

Reaction of 3-mercapto-2-butanone with electron-deficient acetylenic esters in the presence of tert-butyl isocyanide leads to dialkyl 4-hydroxy-4,5-dimethyl-4,5-dihydro-2,3-thiophenedicarboxylates. These alcohols are converted to 2,3-dialkyl-4,5-dimethyl-2,3-tiophenedicarboxylates in boiling dichloromethane in fairly good yields. (E/Z) SFunctionalized vinyl sulfides are produced in this reaction as by- products.