Chiral rhodium complexes derived from electron-rich phosphine-phosphites as asymmetric hydrogenation catalysts

Two new chiral cationic rhodium(I) complexes derived from electron-rich dicyclohexylphosphine-phosphite ligands were prepared from enantiopure Sharpless epoxy ethers. The best-performing catalyst system, which bears a less bulky methyl ether moiety, exhibited remarkably high enantioselectivity (up to 99% ee) and reactivity (up to >2500 TON) in asymmetric hydrogenation reactions of various functionalized alkenes (α-(acylamino)acrylates, itaconic acid derivatives, α-substituted enol esters and α-arylenamides). Our synthetic methodology has been successfully applied to the enantioselective synthesis of the antiepileptic drug (R)-lacosamide (Vimpat).