Synthesis of Formamide Derivatives Catalyzed by Vitamin B₁ Hydrochloride

Thiamine hydrochloride hydrate(=VB₁), also named vitamin B₁ hydrochloride hydrate, has been used as the catalyst of the benzoin condensation due to behavior similar to a cyanide ion. Recently, it has been shown that VB₁ is an efficient catalyst for N-forminations using formic acid as a forminating reagent. In the reactions, the
N-forminations smoothly proceed at 80 °C by the addition of 2 mol% of VB₁ to the mixture of formic acid and amines without any solvents. Various amines such as aromatic and aliphatic amines, and C-protected amino acids can be transformed into the corresponding formamide derivatives. Typically, conventional synthetic methods using formic acid require high temperature conditions, or expensive condensing reagents or metal salts to accomplish the N-forminations. Thus, VB₁ catalyzed N-formination is an easy and convenient synthetic method to produce formamide derivatives.