Elemental Sulfur-Promoted Aerobic Cyclization of Ketones and Aliphatic Amines for Synthesis of Tetrasubstituted Imidazoles

摘要

Elemental sulfur-promoted cyclization for the one-pot synthesis of tetra-substituted imidazoles from benzylamines and ketones is described. Elemental sulfur combined with molecular oxygen as the benign co-oxidant was found to be the key for the high efficiency of this transformation under metal-free conditions. A range of tetrasubstituted imidazoles were synthesized from simple ketones and amines with good functional group tolerance.