Affiliation:
1. Faculty of Chemistry and Biochemistry Ruhr-University Bochum Universitätsstrasse 150 44801 Bochum Germany
Abstract
AbstractBulky ylide‐substituted phosphines have recently found application as potent ligands in homogeneous catalysis. The attempted synthesis of the ylide‐substituted fluorenylphosphine YPhP(Cy)Flu [YPh=Cy3P(Ph)C; Flu=9‐methylfluorenyl] now resulted in the unexpected elimination of 9‐methylenefluorene during the deprotonation step of the intermediary α‐phosphino phosphonium salt to yield the secondary ylide‐substituted phosphine YPhP(Cy)H. This phosphine underwent formal H2 elimination under basic conditions to form a cyclic phosphonium ylide with a P−C−P−C four‐membered ring via deprotonation of one cyclohexyl group of the PCy3 moiety. Upon coordination to transition metals the secondary ylidylphosphine forms a neutral phosphide ligand by shift of the proton into the ylide‐backbone and formation of zwitterionic metal complexes.