Phthalimidesulfenyl chloride; part VII: Synthesis of 2-substituted 3-chlorobenzo[b]thiophenes and related heteroaromatics

Article abstract of DOI:10.1055/s-1994-25516

Addition of phthalimidesulfenyl chloride (1) to diaryl- or alkyl(aryl) acetylenes affords (E)-β-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 substituents at the double bond of vinylsulfenamides 3. Following the same strategy the thienothiophene 11 and the condensed thiopyran 12 were also prepared.