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Selection and Development of a Route for Cholesterol Absorption Inhibitor AZD4121

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journal contribution
posted on 20.04.2012, 00:00 by Staffan Karlsson, J. Henrik Sörensen
The development of a synthetic route to the cholesterol absorption inhibitor AZD4121 is presented. Key steps are a highly enantioselective CBS reduction, a stereospecific Staudinger reaction, an amine/lithium chloride mediated ester hydrolysis, and a resolution of a 50:50 diastereomeric mixture by recrystallization. The synthesis was accomplished in 10 linear steps, and the overall yield, when compared with the lead optimization (LO) route, was improved from 1% to 20%. All purifications of intermediates through preparative HPLC or silica gel chromatography were avoided. This was possible since many of the intermediates along the route could be used as such in the next step until an intermediate with suitable crystalline properties could be identified and purified through crystallization.