PHTHALIMIDESULFENYL CHLORIDE .7. SYNTHESIS OF 2-SUBSTITUTED 3-CHLOROBENZO[B]THIOPHENES AND RELATED HETEROAROMATICS

Addition of phthalimidesulfenyl chloride (1) to diaryl- or alkyl(aryl) acetylenes affords (E)-beta-chlorovinylsulfenamides 3. These species react with aluminum trichloride and other Lewis acids to give benzo[b] thiophenes 6 through an intramolecular electrophilic substitution. The reaction is very simple and seems insensitive to the nature of substi tuents at the double bond of vinylsulfenamides 3. Following the same s trategy the thienothiophene 11 and the condensed thiopyran 12 were als o prepared.