Studies Related to the Robinson Transposition Reaction

Article abstract of DOI:10.1021/jo00222a013

The formation and reactivity of 1,4-dichloro-2-(thio-substituted)-2-butenes is explored, leading to a new bis(phosphonium) salt, 18. 18 may be used as a reagent to effect a functionalized four-carbon annulation sequence, analogous to the well-known Robinson annulation, but yielding enones that are transposed relative to the standard regiochemistry.Some mechanistic studies on the formation of 18 are described, along with trapping studies during the annulation process and various hydrolysis conditions for the resulting dienyl sulfides.Extensive use is made of 13C and 31P NMR and high-field 1H NMR.