Asymmetric heterogeneous catalysis by metalloporphyrins

The synthesis of enantiomerically pure compounds is one of the major challenges in heterogeneous catalysis. The use of heterogeneous catalysts under ambient conditions offers several advantages compared with their homogeneous counterparts, such as ease of recovery and recycling and enhanced stability. Distinct methodologies have been developed for the immobilization of homogeneous catalysts or the creation of heterogeneous catalysts. The current applications of metalloporphyrins in heterogeneous catalytic asymmetric reactions will be herein reported. Preparation of chiral metalloporphyrin polymers and their uses in catalytic asymmetric syntheses will be described. Thus, cyclopropanation reactions using functionalized diazoalkanes as reagents lead to high enantioselectivity and high diastereoselectivity. Catalytic oxidation reactions will also be presented. Comparison between heterogeneous and homogeneous catalysis will be discussed from asymmetric synthesis point of view. (c) 2006 Elsevier B.V. All rights reserved.