A Simple, One-Pot Synthesis of N-Alkyl and N-Aryl Thieno[2,3-d]pyrimidinones from Thiophene- and Benzothiophene-2-yl-ureas

Abstract

We herein describe a convenient, one-pot synthesis of N-substituted thieno and benzothieno[2,3-d]pyrimidinones from the respective thiophene-2-yl ureas. This intramolecular cyclization, which presumably proceeds via a Vilsmeier–Haack dimethyliminium intermediate, has proven to be regioselective when performed in the presence of N,N′-bisarylureas and allows for independent functionalization of the pyrimidinone N3 and C4 positions.