Regiodivergent Approach to α- and β-(Arylthio)alkenylphosphane Oxides and Sulfides: Aminophosphanes as Synthetic Auxiliaries

β-(Arylthio)ethenylphosphane oxides and sulfides are easily prepared by nucleophilic addition of thiophenols to the CºC bond of the respective P,P-diphenyl-P-phenylethynyl P(V) derivatives. The regioisomeric α-(arylthio) analogues can be also prepared, starting from the same activated alkynes, by sequential nucleophilic addition of aminophosphanes and thiophenols. In these latter cases, aminophosphanes, which are recovered at the end of the processes, act just as synthetic auxiliaries for modulating the regiochemical outcome of the global thiophenol addition.