NaHBEt₃-Catalyzed 1,2-Hydroboration of α,β-Unsaturated Carbonyls: Mechanistic Insights into Hydride Transfer Pathways

Abstract

A highly 1,2-selective hydroboration of α,β-unsaturated ketones and aldehydes has been achieved by employing simple and readily available, transition metal-free NaHBEt₃ as a catalyst. This sodium-catalyzed reaction proceeds at room temperature, exclusively furnishing the corresponding allylic alcohols with broad substrate scope and excellent functional group tolerance, including nitrile, amine, esters, nitro groups, alkoxy groups, and halides. Mechanistic studies suggest that (i) BEt₃ serves as a Lewis acid cocatalyst, activating the substrate and facilitating the reaction, (ii) the resting hydride species are H₂Bpin and (EtO)HBpin, and (iii) the rate-determining step involves hydride transfer from these resting species to the carbonyl carbon.

Keywords

Alkali metal catalyst - 1,2-Reduction - α,β-Unsaturated carbonyls - Allylic alcohols - Hydride transfer pathway

Publication History

Received: 11 September 2025

Accepted after revision: 11 November 2025

Accepted Manuscript online:
11 November 2025

Article published online:
01 December 2025

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In terms of hydride donating ability, Na(EtO)HBpin is assumed to be a true hydride donor rather than NaH2Bpin. See:
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