Isomerization of Secondary Phosphirane into Terminal Phosphinidene Complexes: An Analogy between Monovalent Phosphorus and Transition Metals

Abstract

Secondary phosphirane complexes isomerizeabove 100 8 8Ct og ive the corresponding terminal phosphinidene complexes,w hichc an be trapped by alkenes and alkynes. This reaction is ar are instance of the isomerization of aP III derivative into aP I derivative.Itappears to mimic the reductive elimination of alkanes from transition-alkylmetal hydrides.Electrophilic terminal phosphinidene complexes [RP-M-(CO) 5 ]( M= Cr,M o, W) are now recognized as ap owerful synthetic tool in organophosphorus chemistry. [1] They have been generated with av ariety of substituents,b ut the parent species are still not accessible.W eh ave recently shown that the phosphirane complexes derived from cyclohexene are good precursors for [RP-W(CO) 5 ]( R = Cl, Fc). [2,3] This observation led us to investigate the reduction of the chloro derivatives 1 [2] to obtain ap otential precursor of [HP-W(CO) 5 ]. After several attempts (NaH, LiAlH 4 ), we found that Bu 3 SnH was the reagent of choice,t hus giving 2a,b in 59 %y ield [Eq. (1)].