Borane-Catalyzed, Chemoselective Reduction and Hydrofunctionalization of Enones Enabled by B-O Transborylation

The use of stoichiometric organoborane reductants in organic synthesis is well established. Here these reagents have been rendered catalytic through an isodesmic B-O/B-H transborylation applied in the borane-catalyzed, chemoselective alkene reduction and formal hydrofunctionalization of enones. The reaction was found to proceed by a 1,4-hydroboration of the enone and B-O/B-H transborylation with HBpin, enabling catalyst turnover. Single-turnover and isotopic labeling experiments supported the proposed mechanism of catalysis with 1,4-hydroboration and B-O/B-H transborylation as key steps.

Automated summary

The use of stoichiometric organoborane reductants in organic synthesis has been well established. In this study, these reagents were rendered catalytic through an isodesmic B-O/B-H transborylation, enabling borane-catalyzed, chemoselective alkene reduction and formal hydrofunctionalization of enones. The proposed mechanism of catalysis involves 1,4-hydroboration and B-O/B-H transborylation as key steps, supported by single-turnover and isotopic labeling experiments.