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Chemicals >> Reducing Agents

Bis(pinacolato)diboron, B2pin2

See also: Bis(neopentylglycolato)diboron, Tetrahydroxydiboron

Recent Literature

A Pd-catalyzed reaction of water with a diboron compound as the reductant produces clean hydrogen gas under ambient reaction conditions. The B2Pin2-H2O system enables a selective hydrogenation of olefins in the presence of a palladium catalyst.
D. P. Ojha, K. Gadde, K. R. Prabhu, Org. Lett., 2016, 18, 5062-5065.

A B2Pin2-assisted copper-catalyzed semihydrogenation of alkynes provides various alkenes in good to excellent yields with Z-selectivity under mild reaction conditions. The present protocol enabled convenient synthesis of deuterium-substituted Z-alkenes using readily available ethanol-d1 as the deuterium source.
H. Bao, B. Zhou, H. Jin, Y. Liu, J. Org. Chem., 2019, 84, 3579-3589.

Rhodium-catalyzed deoxygenations and borylations of ketones with B2pin2 provide alkenes, vinylboronates, and vinyldiboronates. These reactions offer mild reaction conditions, a broad substrate scope, and excellent functional-group compatibility. Mechanistic studies support that the ketones initially undergo a Rh-catalyzed deoxygenation to give alkenes via boron enolate intermediates.
L. Tao, X. Guo, J. Li, R. Li, Z. Lin, W. Zhao, J. Am. Chem. Soc., 2020, 142, 18118-18127.

The combination of B2pin2 and KOtBu enables a chemoselective, metal-free reduction of aromatic nitro compounds to the corresponding amines in very good yields in isopropanol. The reaction tolerates various reducible functional groups.
H. Lu, Z. Geng, J. Li, D. Zou, Y. Wu, Y. Wu, Org. Lett., 2016, 18, 2774-2776.

A visible-light-promoted transfer hydrogenation of azobenzenes proceeds smoothly in methanol at ambient temperature in the presence of B2pin2 through a radical pathway. The reaction reduces a broad range of azobenzenes to the corresponding hydrazobenzenes in very good yields.
M. Song, H. Zhou, G. Wang, B. Ma, Y. Jiang, J. Yang, C. Huo, X.-C. Wang, J. Org. Chem., 2021, 86, 4804-4811.

An unprecedented nickel-catalyzed reductive borylation of enaminones provides β-ketone boronic esters via a challenging transformation of an alkenyl C(sp2)-N bond. While B2pin2 plays a dual role in this process, water serves as the hydrogen source.
X. Li, Z. Chen, Y. Liu, N. Luo, W. Chen, C. Liu, F. Yu, J. Huang, J. Org. Chem., 2022, 87, 10349-10358.