# Borane–Trimethylamine Complex: A Versatile Reagent in Organic Synthesis

## TL;DR

This review highlights the diverse uses of the borane–trimethylamine complex in organic chemistry, including reductions and cleavage reactions.

## Contribution

The paper provides a focused review on the unique and recent applications of BTM not covered in prior reviews.

## Key findings

- BTM is effective in reducing carbonyl groups and carbon–nitrogen double bonds.
- It enables selective N-monomethylation and reductive deprotection in organic synthesis.
- Recent uses include CO2 utilization and photocatalytic radical chemistry.

## Abstract

Borane–trimethylamine complex (Me3N·BH3; BTM) is the most stable of the amine–borane complexes that are commercially available, and it is cost-effective. It is a valuable reagent in organic chemistry with applications in the reduction of carbonyl groups and carbon–nitrogen double bond reduction, with considerable examples in the reduction of oximes, hydrazones and azines. The transfer hydrogenation of aromatic N-heterocycles and the selective N-monomethylation of primary anilines are further examples of recent applications, whereas the reduction of nitrobenzenes to anilines and the reductive deprotection of N-tritylamines are useful tools in the organic synthesis. Moreover, BTM is the main reagent in the regioselective cleavage of cyclic acetals, a reaction of great importance for carbohydrate chemistry. Recent innovative applications of BTM, such as CO2 utilization as feedstock and radical chemistry by photocatalysis, have extended their usefulness in new reactions. The present review is focused on the applications of borane–trimethylamine complex as a reagent in organic synthesis and has not been covered in previous reviews regarding amine–borane complexes.