Transition Metal-Catalyzed Hydroboration Reactions

Transition metal–catalysed hydroboration entails the addition of a boron–hydrogen bond across unsaturated carbon–carbon bonds under the influence of a metal complex. This reaction has emerged as a cornerstone in modern synthetic chemistry, enabling the rapid and selective assembly of organoboron compounds that serve as versatile intermediates for cross-coupling, functional-group interconversion and the construction of complex molecular architectures. From early demonstrations using precious metals such as rhodium and iridium to recent advances with earth-abundant metals including iron, cobalt, copper and manganese, the field has witnessed remarkable progress in catalyst design, mechanistic understanding and substrate scope. Key considerations in these processes include control over regioselectivity to dictate the site of borylation, stereoselectivity to access defined geometric isomers of alkenylboronates and enantioselectivity to furnish chiral organoboron products. Tailored ligand frameworks—ranging from chiral bisphosphines to pincer scaffolds—have enabled high catalytic efficiencies, often quantified by turnover numbers and frequencies that reflect the robustness of the catalytic cycle. Recent innovations have further exploited photochemical control, remote functionalisation via alkene isomerisation and computational ligand design to expand the repertoire of accessible substrates and enhance operational simplicity. Collectively, these developments underscore the global significance of transition metal–catalysed hydroboration in sustainable synthesis, pharmaceutical discovery and the development of advanced materials.

Research from Nature Portfolio

Recent studies have showcased a cobalt-based catalytic platform that achieves exceptional Z-selectivity in the hydroboration of terminal alkynes. By employing an air-stable CNC pincer ligand, this system operates at ambient temperature with high turnover numbers and a rare time-dependent control over stereoselectivity, enabling the generation of either Z- or E-vinylboronates on demand. Equally transformative has been the integration of computational design into ligand development, where a three-quadrant P-chirogenic bisphosphine ligand was systematically optimised to promote enantioselective Markovnikov hydroboration of aliphatic terminal alkenes. This approach delivered enantiomeric excesses approaching 99 per cent, demonstrating the power of in silico screening in guiding catalyst innovation.

Transition Metal-Catalyzed Hydroboration Reactions publication trend

The graph below shows the total number of articles in transition metal-catalyzed hydroboration reactions across all publications each year (not limited to Nature Index journals).

Technical terms

Hydroboration: Addition of a B–H bond across an unsaturated carbon–carbon bond to form organoboron compounds.

Regioselectivity: Preference for reaction at one positional isomer over another within a substrate.

Stereoselectivity: Preference for formation of one geometric isomer (E or Z) in unsaturated products.

Enantioselectivity: Preference for formation of one enantiomer over its mirror image in chiral products.

Pincer ligand: Tridentate ligand framework that binds a metal at three coordination sites, providing stability and tunable reactivity.

Turnover number (TON): Number of substrate molecules transformed per catalyst molecule before deactivation.

References

1. The transition metal-catalysed hydroboration reaction. Chemical Society Reviews (2022).
2. Cobalt catalyzed practical hydroboration of terminal alkynes with time-dependent stereoselectivity. Nature Communications (2024).
3. Computational design of high-performance ligand for enantioselective Markovnikov hydroboration of aliphatic terminal alkenes. Nature Communications (2018).
4. Copper‐Catalyzed Regio‐ and Enantioselective Hydroboration of Difluoroalkyl‐Substituted Internal Alkenes. Advanced Science (2023).
5. Chemo-, regio-, and stereoselective iron-catalysed hydroboration of alkenes and alkynes. Chemical Communications (2013).
6. Hydroboration of Terminal Alkenes and trans‐1,2‐Diboration of Terminal Alkynes Catalyzed by a Manganese(I) Alkyl Complex. Angewandte Chemie International Edition (2021).