Indium-Catalyzed N-Formylation of Amines under Solvent-Free Conditions

Abstract

We have developed a simple, mild method for N-formylation of a wide variety of amines in the presence of indium metal as a catalyst under solvent-free conditions. This reaction is applicable to the chemoselective N-formylation of amino groups and α-amino acid esters without epimerization.

Key words

amine - formylation - formic acid - indium - ethanol­amine - formylamino ester - solvent-free

References and Notes

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21

Typical procedure for the formylation of amines: A mixture of amine (2 mmol), formic acid (purity = 99%; 226 µL, 6 mmol), and In metal (23 mg, 0.2 mmol) was stirred at 70 ˚C, and the reaction was monitored by TLC. After completion of the reaction, the mixture was diluted with CH₂Cl₂ and filtered through Celite. The filtrate was washed with saturated NaHCO₃ and brine, then dried over anhydrous MgSO₄. After filtration and evaporation of the solvent, the residue was purified by column chromatography on silica gel to give the formylated product.