Recent developments in the synthesis and synthetic applications of borane–amines

Abstract

Borane–amine complexes occupy an increasingly important position in modern main-group chemistry. Their tunable electronic and steric properties offer a balance between the high reactivity of borane and enhanced stability provided by amine coordination, making them unique reagents for organic synthesis and materials chemistry. This feature article presents a review of the recent advances in the synthesis of borane–amines, as well as their diverse synthetic applications. The main synthetic strategies for the preparation of borane–amines, direct reaction with diborane or in situ generated borane, salt metathesis, and Lewis base exchange, are discussed in detail with emphasis on recent protocols and borane–ammonia preparation techniques. Applications of borane–amines in organic synthesis where they serve as selective and more easily handled alternatives to traditional borane reagents include reduction, reductive amination, and hydroboration reactions. Recent progress demonstrates that beyond their use as practical borane alternatives, borane–amines offer distinct mechanistic and synthetic utility in transfer hydrogenation, borylation, B–H insertion, as sources of amine–ligated boryl radicals, and as amine surrogates in amidation methodologies. This feature article aims to consolidate recent developments in well-known reactions and emerging methodologies, as well as underscore the growing role of borane–amines as adaptable tools in synthetic organic chemistry.