Stereocontrolled Synthesis of (22<i>R</i>)-22-Hydroxycholesterol Guided by α-Silyl Radical Stabilization

Abstract

Abstract The synthesis of (22R)-22-hydroxycholesterol, featuring formation of three contiguous chiral centers (C-17, 20, and 22) in a single step by the use of a 6-endo α-silyl radical-mediated cyclization is presented. Additionally, an interesting protiodesilylation used to activate a cyclic siloxane towards C–Si bond oxidation, and a modified, bulky aryl thionocaronate reagent for regioselective diol-monodeoxygenation are described.