The mechanism of the reaction involves initial formation of the phosphonium anhydride 3 10 (Scheme 2). The formation and reactivity of other phosphonium anhydrides, such as the Hendrickson reagent, is reported elsewhere. 11 Formation of 3 could be followed by attack of the pentanethiolate to give 4a, which in the presence of excess thiolate could be expected to give the phosphorane5. Reductive elimination of the disulfide from 5 would give the phosphine2. ...
