Metal/linked-BINOL complexes: Applications in direct catalytic asymmetric Mannich-type reactions

Development of metal/linked-BINOL complexes and their applications in direct catalytic asymmetric Mannich-type reactions of hydroxyketones are reviewed. A Et2Zn/linked-BINOL complex was effective for diastereo- and enantioselective synthesis of beta-amino alcohols. By choosing the proper protective groups on the imine nitrogen, either anti- or syn-beta-amino alcohol was obtained in excellent enantioselectivity (up to > 99.5% ee) using the same zinc catalysis. Y{N(SiMe3)(2)}(3)/linked-BINOL complex was effective for various hydroxyketones, affording syn-beta-amino alcohols with high enantioselectivity (up to 98% ee). To broaden the nucleophile scope to carboxylic acid derivatives, N-acylpyrrole was utilized as an ester equivalent donor. In(O-iPr)(3)/linked-BINOL complex was effective for generating an In-enolate from N-acylpyrrole in situ, giving Mannich adducts with high enantioselectivity (up to 98% ee). (c) 2005 Elsevier B.V. All rights reserved.