Sulfamic acid: an efficient, cost-effective and recyclable solid acid catalyst for the three-component synthesis of α-amino nitriles

α-Amino nitriles are synthesized by the three-component coupling reaction of aldehydes, amines and trimethylsilyl cyanide using sulfamic acid as a heterogeneous solid acid catalyst, under solvent-free conditions in excellent yields. The catalyst was recovered by simple filtration and was recycled in subsequent reactions.