Chiral Syn-1,3-diol Derivatives via a One-Pot Diastereoselective Carboxylation/ Bromocyclization of Homoallylic Alcohols

Chiral syn-1,3-diols are fundamental structural motifs in many natural products and drugs. The traditional Narasaka-Prasad diastereoselective reduction from chiral β-hydroxyketones is an important process for the synthesis of these functionalized syn-1,3-diols, but it is of limited applicability for large-scale synthesis because (1) highly diastereoselective control requires extra explosive and flammable Et(2)BOMe as a chelating agent under cryogenic conditions and (2) only a few functional syn-1,3-diol scaffolds are available. Those involving halogen-functionalized syn-1,3-diols are much less common. There are no reported diastereoselective reactions involving chemical fixation of CO(2)/bromocyclization of homoallylic alcohols to halogen-containing chiral syn-1,3-diols. Herein, we report an asymmetric synthesis of syn-1,3-diol derivatives via direct diastereoselective carboxylation/bromocyclization with both relative and absolute stereocontrol utilizing chiral homoallylic alcohols and CO(2) in one pot with up to 91% yield, > 99% ee, and >19:1 dr. The power of this methodology has been demonstrated by the asymmetric synthesis of statins at the pilot plant scale.