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.
Keywords: t-butyl isocyanide, 3-mercapto-2-butanone, acetylenic esters, vinyl sulfides, thiophenes, SH-acid
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