Proline as Co-catalyst

To improve the enantioselectivities, we then reinvestigated Hatakeyama s cinchona-derived catalyst, p-ICD, promoted MBH reaction of aldehydes with methyl vinyl ketone or (ot)-naphthyl acrylate in the presence of co-catalyst. The enantioselectivities increased in some cases, and the absolute configuration of the MBH adducts can be inverted by the use of proline or lithium 

R = 2-N02Ph, 1-N02-2-naphthyl, 4-N02Ph, 2-fuiyl, 2,4-(N02 2Ph, 3-Me0-2-N02Ph, 2-CFjPh 

At = 4-N02Ph, 4-CF3Ph, 4-BrPh, 4-CNPh, 2-CIPh, 3-CIPh, 4-CIPh, a-NOzPh, 3-BrPh, 2-CNPh, 2-FPh, 2-CI-5-N02Ph, Ph, 4-MeOPh, 4-MePh, 2-naphthyl, 2-furyl 

Recently, Tanaka and Barbas et al. have reported an imidazole and proline co-catalytic system for the readion between enals and A-/ -methoxyphenyl-(PMP) 

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