Organic chemistry

Combinatorial chemistry

Boranes

Boron

Catalysis

Nucleophile

Hydroboration

Chemistry

Diborane

Borane

Catalytic cycle

ACS Catalysis

The continued development of hydroboration catalysts typifies the importance of this transformation as a testbed for catalytic activity and as a fundamental reaction for organic synthesis. Catalytic hydroboration studies routinely investigated the decomposition of HBcat but in the case of HBpin, decomposition is not commonly considered because of its perceived stability. Organoboranes catalyze the hydroboration of alkenes and alkynes; these species can be formed from the facile decomposition of 1,3,2-dioxaborolanes (e.g., HBcat and HBpin) by nucleophiles and Lewis acids. Similarly, the nucleophilic decomposition of 1,3,2-dioxaborolanes to borohydride species can catalyze the reduction of carbonyl derivatives. These motifs are abundant in hydroboration catalysis; therefore, the potential for hidden boron catalysis is high and must be controlled for. This Perspective discusses the current methods for probing 1,3,2-dioxaborolane decomposition, highlights the need to consider this hidden catalysis in the future development of hydroboration catalysis, and proposes a set of protocols for the identification of hidden boron catalysis.

The Hidden Role of Boranes and Borohydrides in Hydroboration Catalysis