Rhodium-catalyzed asymmetric 1,4-addition of organoboron reagents to 5,6-dihydro-2(1H)-pyridinones. Asymmetric synthesis of 4-aryl-2-piperidinones

Catalytic asymmetric synthesis of 4-aryl-2-piperidinones was realized for t he first time by asymmetric 1,4-addition of arylboron reagents to 5,6-dihyd ro-2(1H)-pyridinones in the presence of a chiral bisphosphine-rhodium catal yst. In the reaction introducing 4-fluorophenyl group, the use of 4-fluorop henylboroxine and 1 equiv (to boron) of water at 40 degreesC gave the highe st yield of the arylation product with high enantioselectivity (98% ee). Th e (R)-4-(4-fluorophenyl)-2-piperidinone obtained here is a key intermediate for the synthesis of (-)-Paroxetine.