Thiophene, benzo[b]thiophene and dibenzo[b,d]thiophene as precursors to highly conjugated organosulfur compounds

This account concerns the use of thiophenes (thiophene, benzo[b]thiophene and dibenzo[b,d]thiophene) to synthesize unusual organosulfur molecules, including a,P-unsaturated thioaldehydes, ylidenecyclohexadienethiones, alpha,beta-unsaturated thioketones, butadirnyl alkyl sulfides and omicron-(organylthio)styrenes, which are not easily accessible by usual organic chemistry methodologies, As a general procedure, thiophenes are cleaved by action of a metal fragment (Rh or Ir) to give C-S insertion products, which undergo regioselective electrophilic attack at either the metalated carbon or sulfur atoms depending on the nature of the electrophile. Subsequent carbonylation reactions in autoclaves liberate the organosulfur products from the metals, which are recovered as bis(carbonyl) complexes.