Asymmetric hydrogenation of unsaturated ureas with the BIPI ligands.
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.
Busacca
Carl A
CA
Department of Chemical Development, Boehringer-Ingelheim Pharmaceuticals, Inc., 900 Ridgebury Road, Ridgefield, Connecticut 06877, USA. cbusacca@rdg.boehringer-ingelheim.com
Lorenz
Jon C
JC
Grinberg
Nelu
N
Haddad
Nizar
N
Lee
Heewon
H
Li
Zhibin
Z
Liang
Mary
M
Reeves
Diana
D
Saha
Anjan
A
Varsolona
Rich
R
Senanayake
Chris H
CH
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*
D004952:Esters; D008024:Ligands; D010720:Phosphines; D014508:Urea; D012238:Rhodium