Catalyst freeN-formylation of aromatic and aliphatic amines exploiting reductive formylation of CO2using NaBH4

Abstract

Herein, we report a sustainable approach forN-formylation of aromatic as well as aliphatic amines using sodium borohydride and carbon dioxide gas. The developed approach is catalyst free, and does not need pressure or a specialized reaction assembly. The reductive formylation of CO2with sodium borohydride generates formoxy borohydride speciesin situ, as confirmed by1H and11B NMR spectroscopy. Thein situformation of formoxy borohydride species is prominent in formamide based solvents and is critical for the success of theN-formylation reactions. The formoxy borohydride is also found to promote transamidation reactions as a competitive pathway along with reductive functionalization of CO2with amine leading toN-formylation of amines.