Diastereodivergent Synthesis of (+)-α-Conhydrine and (−)-β-Conhydrine from a η,γ-Dibromo-β-ketosulfoxide

Abstract

Diastereodivergent syntheses of the enantiopure hemlock alkaloid (+)-α-conhydrine and its diastereomer (−)-β-conhydrine are reported. Our approach relies on efficient Crystallization-Induced Diastereomer Transformation (CIDT) of an epimeric mixture of a η,γ-dibromo-β-ketosulfoxide, optically pure only at the sulfur atom, that provided a stable α-bromoketone, and diastereoselective β-ketosulfoxide reduction that led to the corresponding anti and syn-bromohydrins with high level of asymmetric induction.