9-Borabicyclo[3.3.1]nonane, 9-BBN

9-Borabicyclo[3.3.1]nonane is a mild reagent for the reduction of carbonyl compounds, acid chlorides and alkenes. As 9-BBN does not form complexes with tertiary amines, a stoichiometric amount of the reagent is sufficient for the complete reduction of amides to amines.

Recent Literature

Organoborane reductants have been rendered catalytic through an isodesmic B-O/B-H transborylation applied in the borane-catalyzed, chemoselective alkene reduction and formal hydrofunctionalization of enones. The reaction proceeds via a 1,4-hydroboration of the enone and B-O/B-H transborylation with HBpin, enabling catalyst turnover.
K. Nicholson, T. Langer, S. P. Thomas, Org. Lett., 2021, 23, 2498-2504.

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.