Bifunctional asymmetric phase-transfercatalysts bearing multiple hydrogen-bonding donors have rarely been explored. The first quaternary ammonium type of these catalysts derived from cinchona alkaloids were readily prepared and found to be highly efficient catalysts for asymmetric nitro-Mannichreactions of amidosulfones. Compared with previous reports, very broad substrate generality was observed
作者:Xianxing Jiang、Yifu Zhang、Lipeng Wu、Gen Zhang、Xing Liu、Hailong Zhang、Dan Fu、Rui Wang
DOI:10.1002/adsc.200900413
日期:2009.9
doubly stereocontrolled organocatalytic aza-Henry reaction of nitroalkanes to N-Boc-imines generated in situfrom a variety of substituted α-amidosulfones was investigated for the first time, in general, affording the corresponding products with high to excellent yields (up to 93% yield) and enantioselectivities (up to 98% ee), and satisfactory diastereoselectivies (anti/syn up to 98:2). Furthermore
New chiral bifunctional thiourea-phosphonium salts have been developed based on natural amino acids as highly efficient phase-transfer catalysts in the enantioselectiveaza-Henryreaction.
New quaternary ammonium types of bifunctional asymmetric phase-transfercatalysts bearing multiple hydrogen-bonding donors derived from α-amino acids were readily prepared and found to be highly efficient in the asymmetric nitro-Mannich reactions of amidosulfones. Very broad substrate generality was observed, and the products were achieved in high enantio-/diastereoselectivities (90–>99.9% ee, 90 : 10