Synthesis of (4-chlorophenyl)-(1-oxo-1λ4-benzo[b]thien-2-yl)methanone and study of its reactivity towards sulfur- and oxygen-containing nucleophiles

Article abstract of DOI:10.1016/S0040-4020(98)00929-6

(4-Chlorophenyl)-(1-oxo-1λ⁴-benzo[b]thien-2-yl)methanone 2a was synthesized by oxidation of the corresponding benzo[b]thiophene derivative 2 with the oxidative system H₂O₂/TFA. This benzo[b]thiophene sulfoxide undergoes Michael-type nucleophilic addition of sulfur- and oxygen-containing nucleophiles either under basic conditions leading to 2,3-dihydro-3- substituted-benzo[b]-thiophene 1-oxides or in acidic media leading then to rearomatized 3-substituted-benzo[b]thiophenes. This method provides an easy two-step functionalization of 2-acyl-benzo[b]thiophene derivatives.