enolates which afford syn-α-iodethyl-β-hydroxyketones stereoselectively upon subsequent reaction with various aldehydes. The aldol adducts are cyclized into trans-acyltetrahydrofurans in good yield by active alumina. In contrast, the use of Et2AlI in place of TiCl4-n-Bu4NI provides the corresponding anti aldol adducts with high stereoselectivity. These methods can complementarily provide both syn and
Highly Stereoselective Reductions of α-Alkyl-1,3-diketones and α-Alkyl-β-keto Esters Catalyzed by Isolated NADPH-Dependent Ketoreductases
作者:Dimitris Kalaitzakis、J. David Rozzell、Spiros Kambourakis、Ioulia Smonou
DOI:10.1021/ol051166d
日期:2005.10.1
[GRAPHICS]The biocatalytic reduction of alpha-alkyl-1,3-diketones and alpha-alkyl-beta-keto esters employing 1 of 20 different isolated NADPH-dependent ketoreductases proved to be a highly efficient method for the preparation of optically pure keto alcohols or hydroxy esters.
Highly diastereoselective synthesis of 2-substituted-1,3-diols catalyzed by ketoreductases
作者:Dimitris Kalaitzakis、Ioulia Smonou
DOI:10.1016/j.tet.2010.09.096
日期:2010.11
The stereoselective reduction of alpha-substituted-beta-hydroxy ketones for the preparation of the corresponding optically pure 2-monosubstituted or 2-disubstituted-1,3-diols is described. These transformations proceed in high optical purities and yields. Ketoreductases were able to catalyze the formation of either the syn or the anti diol, depending on the enzyme. By replacing the a-alkyl substituent for an OAc moiety, in low conversion time (<= 24 h), ketoreductases catalyzed the formation of the OAc-protected 1,2,3-triol, in high yield and with high optical purity (>99% de, >99% ee). This is a simple and highly stereoselective method for the synthesis of different diastereomers of chiral diols. (C) 2010 Elsevier Ltd. All rights reserved.