Amine Boranes as Selective Reducing and Hydroborating Agents. A Review

Experimental and Theoretical Studies of the Potential Interconversion of the Amine–Borane iPr2NH·BH(C6F5)2 and the Aminoborane iPr2N=B(C6F5)2 Involving Hydrogen Loss and Uptake

“…[1][2][3] Of these species, amine-borane adducts, R x NH 3-x ·BH 3 , are an interesting subclass that can exhibit unique reactivity due to the presence of both protic and hydridic hydrogen atoms. The elimination of dihydrogen from molecules of this type affords new intra-or intermolecular boron-nitrogen bonds, and a wide range of catalysts have now been reported which can promote such processes under mild conditions (Scheme 1).…”

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The amine-borane adduct iPr 2 NH·BH(C 6 F 5 ) 2 (1) and the aminoborane iPr 2 N=B(C 6 F 5 ) 2 (2) have been prepared and crystallographically characterised. Interconversion between the two compounds has been attempted using thermal and transition-metal-catalysed dehydrogenation and hydrogenation protocols and the overall reaction thermodynamics were probed by computational methods.

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Mechanisms of chemical generation of volatile hydrides for trace element determination (IUPAC Technical Report)

“…A representative example is the reduction of ketones by very weak reducing agents, such as BH 3 (Me 3 N) and BH 3 (morpholine). In this case, the protonation of the carbonyl group (38) results in an increased rate of reduction, which has been estimated to be ≈10 11 times faster than for the non-protonated carbonyl group [118]. The activation of the reducible group by protonation was one of the possible reaction pathways considered by Brown and Murray [111] [9].…”

Sixty Years of Hydride Reductions

“…We have shown that borane-1,4-thioxane complex (134) Borane-amines. Although amine-boranes have been known for several decades (136,137), they have not yet found significant use in organic reductions and syntheses as one might expect. This may be due to the strong coordination of the nitrogen lone pair and the boron, since dissociation appears to be a key step for reaction.…”

“…One of the borane-amines currently available that deserve special attention is pyridine-borane (136). This reagent is capable of reducing aldehyde oximes to the corresponding hydroxylamines (eq 81) (138) and is also used for reductive animations (139).…”