title: Asymmetric hydrogenation of unsaturated ureas with the BIPI ligands.
abstract: Asymmetric hydrogenation of unsaturated urea esters with the BIPI Ligands has been examined. Optimization of the P-N ligand structure has led to the development of chiral rhodium catalysts capable of producing the targets with >99% ee. The critical phosphine borane SNAr reaction needed for ligand synthesis has been optimized to give the adducts in high yield at ambient temperature with no racemization. An extremely concise, economical, and scalable sequence to these important new ligands for catalysis of asymmetric hydrogenation has been developed.
authors: Department of Chemical Development, Boehringer-Ingelheim Pharmaceuticals, Inc., 900 Ridgebury Road, Ridgefield, Connecticut 06877, USA. cbusacca@rdg.boehringer-ingelheim.com
authors: Carl A
authors: CA
authors: Busacca
authors: Jon C
authors: JC
authors: Lorenz
authors: Nelu
authors: N
authors: Grinberg
authors: Nizar
authors: N
authors: Haddad
authors: Heewon
authors: H
authors: Lee
authors: Zhibin
authors: Z
authors: Li
authors: Mary
authors: M
authors: Liang
authors: Diana
authors: D
authors: Reeves
authors: Anjan
authors: A
authors: Saha
authors: Rich
authors: R
authors: Varsolona
authors: Chris H
authors: CH
authors: Senanayake
mesh_terms: D002384:Catalysis; D004952:Esters; D006865:Hydrogenation; D008024:Ligands; D015394:Molecular Structure; D010720:Phosphines / Q000737:chemistry*; D012238:Rhodium / Q000737:chemistry*; D013237:Stereoisomerism; D014508:Urea / Q000031:analogs & derivatives* / Q000737:chemistry*
chemical_list: D004952:Esters; D008024:Ligands; D010720:Phosphines; D014508:Urea; D012238:Rhodium