Probing electronic effects in the asymmetric Heck reaction with the BIPI ligands.
[structure: see text] The new BIPI ligands are phosphinoimidazolines that can be electronically tuned in three different ligand regions to explore electronic effects in asymmetric catalysis. Their application to the asymmetric Heck reaction (AHR) in the creation of a chiral quaternary center is described. Enantioselectivity is shown for the first time to depend linearly on phosphine electron density. Changing the ligand basicity by variation of the R(2) or R(3) substituents reverses facial selectivity.
Busacca
Carl A
CA
Department of Chemical Development, Boehringer-Ingelheim Pharmaceuticals, Inc., 900 Ridgebury Rd., Ridgefield, Connecticut 06877, USA. cbusacca@rdg.boehringer-ingelheim.com
Grossbach
Danja
D
So
Regina C
RC
O'Brien
Erin M
EM
Spinelli
Earl M
EM
D002384:Catalysis; D004583:Electrons; D007093:Imidazoles / Q000737:chemistry*; D008024:Ligands; D010720:Phosphines / Q000737:chemistry*; D013237:Stereoisomerism
D007093:Imidazoles; D008024:Ligands; D010720:Phosphines