Solvent and in situ catalyst preparation impacts upon Noyori reductions of aryl-chloromethyl ketones: application to syntheses of chiral 2-amino-1-aryl-ethanols

摘要

As part of medicinal chemistry efforts we found it necessary to develop general syntheses of highly enantiomerically enriched 1-aryl-2-chloroethanols and 1-aryl-2-methylaminoethanols. A survey of literature methods suggested that a truly general approach had not yet been reported, encouraging us to undertake the development of such a methodology. This study describes the design, development, and reduction to practice of a general synthesis of chiral 1-aryl-2-chloroethanols and the transformation of these entities to highly enantiomerically enriched 1-aryl-2-methylaminoethanols. Of particular importance were observations of the impact of solvent and the method of catalyst preparation on the yield and enantiomerical excess of chlorohydrins prepared via Noyori transfer hydrogenations of aryl-chloromethyl ketones. (c) 2006 Elsevier Ltd. All rights reserved.