BINAP versus BINAP(O) in Asymmetric Intermolecular Mizoroki-Heck Reactions: Substantial Effects on Selectivities

2,2'-Bis(diphenylphosphino)-1,1'-binaphthyl (BINAP) was employed as chiral ligand in the enantioselective intermolecular Mizoroki-Heck reaction, whereas the use of cognate BINAP(O) (monooxidized BINAP) is unprecedented. The regio- and enantioselectivity of the arylation of representative cyclic alkenes changes dramatically in the presence of hemilabile BINAP(O) instead of BINAP. The arylation of 2,3-dihydrofuran is perfectly regiodivergent (98:2 versus 0:100) and the arylation of cyclopentene is only enantioselective with BINAP(O) [60 versus 10% enantiomeric excess (ee)]. Use of [Pd-2(dba)(3)]center dot dba ( dba = dibenzylideneacetone) instead of Pd(OAc)(2) produces as high as 86% ee in the arylation of cyclopentene.