Triethylamine Catalyzed Reductive CO2 to Form N‐Formylation of Amines and Hydrazides

Abstract Carbon dioxide was one of the main green‐house gas, using CO 2 as a C1 source to produce functional chemicals can relieve environmental issues. With the development of the N‐formylation reaction of amines under a CO 2 atmosphere, a promising route for the synthesis of diacylhydrazines is the N‐formylation of hydrazide with CO 2 in the presence of a reducing agent. Triethylamine (TEA) is an organic base commonly used in organic synthesis, which has a low boiling point to easily separated from the system by decompression distillation. We herein describe TEA‐ catalyzed selective N‐formylation of amines/ hydrazide using CO 2 and NaBH 4 to construct various formamide and N′‐formyl‐hydrazide. Utilizing N‐formylation of amines reaction to tune the reaction solvent, base, and temperature given a lower boiling catalyst and solvent system and the product can be separated easily. The selective synthesis method of formamides is achieved in good yields, which is also equally adapted to hydrazides. Finally, 1,3,4‐oxadiazole skeleton having synthetic drugs and material application was obtained by cyclization of N′‐formyl‐hydrazide.