This review is a guided tour along the activation modes and reactivity of B–B, B–Si, B–N, B–S, B–Se and B–P reagents, in the absence of any transition metal complex.

Boron compounds have been traditionally regarded as “Lewis acids” preferring to accept electrons rather than donate them in the course of their reactions but current examples of unusual reactivity between tricoordinated boranes and electrophilic sites suggest a new conceptual context for the boryl moieties, based on their nucleophilic character which can be enhanced depending on the substituents on boron.