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.
GRAPHICAL ABSTRACT
![](/cms/asset/ceb458bc-b90b-4679-be36-4730223eb025/lsyc_a_596985_o_uf0001.gif)
ACKNOWLEDGMENTS
The authors would like to thank Craig Avery for useful discussion, and Biota Europe Ltd (UK) for support during the course of this research.