Potassium Hydroxide/Dimethyl Sulfoxide Promoted Intramolecular Cyclization for the Synthesis of Benzimidazol-2-ones

A new protocol for intramolecular N-arylations of ureas to form benzimidazol-2-ones has been developed. The cyclization reaction occurs In the presence of KOH and DMSO at close to ambient temperature. Under these conditions the yields are high and a wide range of functional groups are tolerated.