Stereoselective catalytic hydrogenation and conjugate reduction of 4-methyl itaconate derivatives bearing a chiral auxiliary

The catalytic hydrogenation of 4-methyl itaconate derivatives bearing a chiral auxiliary and their conjugate reduction with n-Bu3SnH in the presence of Lewis acid were examined to reveal their diastereoselectivity. The homogeneous catalytic hydrogenation of 4-methyl itaconyl (1S)-(−)-2,10-camphorsultam with the Crabtree's catalyst [Ir(COD)(PCy3)(py)]PF6 in CH2Cl2-MeOH (2:1 v/v) gave less polar (1S,2′S)-diastereomer in 84% yield, while the conjugate reduction of the α-methylene amide with n-Bu3SnH (2 equiv) using MgI2 (7 equiv) as an additive in CH2Cl2 gave more polar (1S,2′R)-diastereomer in 70% yield.