Catalyst-free reductions of nitriles to amino-boranes using sodium amidoborane and lithium borohydride

Abstract

An efficient and facile method to reduce nitriles to amine-boranes was developed. Aromatic and aliphatic nitriles were readily reduced in the presence of both sodium amidoborane (NaAB) and LiBH₄ at room temperature in THF without catalysts, affording products in up to 99% yield. The products can be easily hydrolyzed to afford primary amines or utilized as reducing reagents for one-pot reductive amination. The key finding of the reaction study is the synergy effect between NaAB and LiBH₄; otherwise the reaction yield would drop substantially from 92% to 22% or 12% when NaAB and LiBH₄ are used separately.