Diphenylammonium Triflate: A Novel and Efficient Catalyst for Synthesis of Spiro-Heterocyclic Compounds

A general and practical one-pot synthesis of spiro-heterocyclic compounds using diphenylammonium triflate (DPAT, 5 mol%) as a novel and efficient catalyst is described. The pseudo four-components Biginelli-like reaction of 5,5- dimethyl-1,3-cyclohexanedione, thiourea and aldehydes catalyzed by DPAT in refluxing ethanol produced the corresponding spiro-heterocyclic compounds with moderate to good yields. A possible mechanism is proposed.