The immobilized NaHSO4·H2O on activated charcoal: a highly efficient promoter system for N-formylation of amines with ethyl formate

The immobilized NaHSO4·H2O on activated charcoal was used as a highly efficient promoter system for facile N-formylation of amines with ethyl formate. All reactions were carried out in refluxing ethyl formate (54 ?C) under mild conditions within 10-100 min to afford the product formamides in high to excellent yields (80-94%).