In contrast to the established dogma that B(C₆F₅)₃ is irreversibly poisoned by excess H₂O/amine (or imine) bases, B(C₆F₅)₃ is actually a water-tolerant catalyst for the reductive amination of primary and secondary arylamines with aldehydes and ketones in “wet solvents” at raised temperatures and using only 1.2 equiv of Me₂PhSiH as reductant. Arylamines/N-arylimines do not result in the irreversible deprotonation of H₂O–B(C₆F₅)₃, allowing sufficient B(C₆F₅)₃ to be evolved at raised temperatures to effect catalytic reductions. Stronger Brønsted basic amines such as ^tBuNH₂ (and derived imines) result in irreversible formation of [HO–B(C₆F₅)₃]⁻ from H₂O–B(C₆F₅)₃, precluding the formation of B(C₆F₅)₃ at raised temperatures and thus preventing any imine reduction. A substrate scope exploration using 1 mol % nonpurified B(C₆F₅)₃ and “wet solvents” demonstrates that this is an operationally simple and effective methodology for the production of secondary and tertiary arylamines in high yield, with imine reduction proceeding in preference to other possible reactions catalyzed by B(C₆F₅)₃, including the dehydrosilylation of H₂O and the reduction of carbonyl moieties (e.g., esters).

BCl₃ is an inexpensive electrophile which induces the borylative cyclization of a wide range of substituted alkynes to regioselectively form polycycles containing synthetically versatile C(sp²)boronate esters. It proceeds rapidly, with good yields and is compatible with a range of functional groups and substitution patterns. Intermolecular 1,2‐carboboration of alkynes is also achieved using BCl₃ to generate trisubstituted vinyl boronate esters.

Lower Lewis acidity boranes demonstrate greater tolerance to combinations of water/strong Brønsted bases than B(C₆F₅)₃, this enables Si−H bond activation by a frustrated Lewis pair (FLP) mechanism to proceed in the presence of H₂O/alkylamines. Specifically, BPh₃ has improved water tolerance in the presence of alkylamines as the Brønsted acidic adduct H₂O–BPh₃ does not undergo irreversible deprotonation with aliphatic amines in contrast to H₂O–B(C₆F₅)₃. Therefore BPh₃ is a catalyst for the reductive amination of aldehydes and ketones with alkylamines using silanes as reductants. A range of amines inaccessible using B(C₆F₅)₃ as catalyst, were accessible by reductive amination catalysed by BPh₃ via an operationally simple methodology requiring no purification of BPh₃ or reagents/solvent. BPh₃ has a complementary reductive amination scope to B(C₆F₅)₃ with the former not an effective catalyst for the reductive amination of arylamines, while the latter is not an effective catalyst for the reductive amination of alkylamines. This disparity is due to the different pK_a values of the water–borane adducts and the greater susceptibility of BPh₃ species towards protodeboronation. An understanding of the deactivation processes occurring using B(C₆F₅)₃ and BPh₃ as reductive amination catalysts led to the identification of a third triarylborane, B(3,5‐Cl₂C₆H₃)₃, that has a broader substrate scope being able to catalyse the reductive amination of both aryl and alkyl amines with carbonyls.