摘要:
A biphenol-based chiral phosphoric acid bearing a 9-anthryl group at each of the 3,3'-positions catalyzed the asymmetric Mannich-type reaction of N-Boc Imine with difluoroenol silyl ethers In the presence of MS3A In THF to afford beta-amino-alpha,alpha-difluoroketones In good yields and with excellent enantioselectivities. Optically pure 3,3-difluoroazetidin-2-one was readily synthesized from the Mannich-adduct.