A Designer Axially Chiral Amino Sulfonamide as an Efficient Organocatalyst for Direct Asymmetric<i>anti</i>-Selective Mannich Reactions and<i>syn</i>-Selective Cross-Aldol Reactions
作者:Taichi Kano、Yukako Yamaguchi、Keiji Maruoka
DOI:10.1002/chem.200900267
日期:2009.7.6
Aminosulfonamide catalyst: A distal proton of the axiallychiralaminosulfonamide (S)‐1 realized the opposite diastereoselectivity in Mannich and cross‐aldol reactions compared with that observed in proline‐catalyzedreactions. The reactionscatalyzed by (S)‐1 proceeded smoothly to give the anti‐Mannich and syn‐aldol adducts in excellent enantioselectivity (see scheme).
A Designer Axially Chiral Amino Sulfonamide as an Efficient Organocatalyst for Direct Asymmetric Mannich Reactions of N-Boc-Protected Imines
作者:Taichi Kano、Yukako Yamaguchi、Keiji Maruoka
DOI:10.1002/anie.200805628
日期:2009.2.23
The moderate nucleophilicity of the axiallychiralaminosulfonamide (S)‐1 suppresses the problematic side reactions, including aldol reactions, in the asymmetricMannichreaction of N‐Boc‐protected imines with aldehydes. The corresponding adducts are obtained in good yield and excellent stereoselectivity (see scheme; Boc=tert‐butoxycarbonyl, Tf=trifluoromethanesulfonyl).