Organocatalysis in Ionic Liquids: Highly Efficient<scp>l</scp>-Proline-Catalyzed Direct Asymmetric Mannich Reactions Involving Ketone and Aldehyde Nucleophiles
作者:Carlos F. Barbas III、Naidu S. Chowdari、D. B. Ramachary
DOI:10.1055/s-2003-41483
日期:——
asymmetric Mannich reactions of N-PMP protected a-imino ethyl glyoxylate with various alde- hydes and ketones in ionic liquids afforded both a- and b-amino acid derivatives with excellent yields and enantioselectivities, providing facile product isolation, catalyst recycling, and signifi- cantly improved reaction rates, ca 4- to 50-fold. Three component Mannich reactionsinvolving other imines also
The Scope of the Direct Proline-Catalyzed Asymmetric Addition of Ketones to Imines
作者:Wolfgang Notz、Shin-ichi Watanabe、Naidu S. Chowdari、Guofu Zhong、Juan M. Betancort、Fujie Tanaka、Carlos F. Barbas
DOI:10.1002/adsc.200404114
日期:2004.8
A full account of catalytic direct asymmetric Mannich-type reactions is presented describing the scope of amino acid-catalyzed additions of unmodified ketones to a large variety of imines. These reactions are performed under very mild, operationally simple, and environmentally friendly and benign conditions employing a one-pot, three-component protocol as well as preformed imines. Typically, products
High pressure induced by water-freezing has been successfully applied to the direct catalytic asymmetric-three component List-Barbas-Mannich reaction, in which higher yield and better enantioselectivity can be realized than those from the reaction at room temperature under 0.1 MPa.