Boron-Promoted Deprotonative Conjugate Addition: Geminal Diborons as Soft Pronucleophiles and Acyl Anion Equivalents

Conjugate addition of alpha-boron-stabilized carbanions is an underexplored reaction modality. Existing methods require deborylation of geminal di-/triboryl alkanes and/or the presence of additional activating groups. We report the 1,4-addition of alpha,alpha-diboryl carbanions generated via deprotonation of the corresponding geminal diborons. The methodology provided a general route to highly substituted and synthetically useful gamma,gamma-diboryl ketones. The development of geminal diborons as soft pronucleophiles also enabled their use as acyl anion equivalents via a one-pot tandem conjugate addition-oxidation sequence.

Automated summary

The conjugate addition of alpha-boron-stabilized carbanions is an underexplored reaction modality. We report the 1,4-addition of alpha,alpha-diboryl carbanions generated via deprotonation of the corresponding geminal diborons, providing a general route to highly substituted gamma,gamma-diboryl ketones.