Simonis Chromone Cyclization

E. Petschek, H. Simonis, Ber. 46, 2014 (1913).

Formation of chromones from phenol and β-keto esters in the presence of phosphorus pentoxide, phosphorus oxychloride or sulfuric acid. Coumarins may also form (Pechmann condensation, q.v.):

Reviews: S. M. Sethna, N. M. Shah, Chem. Rev. 36, 14 (1945); S. M. Sethna, R. Phadke, Org. React. 7, 15 (1953); R. N. Lacey, J. Chem. Soc. 1954, 854; O. Dann, G. Illing, Ann. 605, 158 (1957); S. F. Tan, Aust. J. Chem. 25, 1367 (1972).