Photocyclization Reactions. Part 5 [1]. Synthesis of Dihydrobenzofuranols Using Photocyclization of 2-Alkoxybenzophenones and Ethyl 2-Benzoylphenoxyacetates

Article abstract of DOI:10.1002/jhet.5570330641

Photocyclization reactions were carried out on 2-alkoxybenzophenones 1a-h and ethyl 2-benzoylphenoxyacetates 2a-e in acetonitrile. Irradiation of 1a-h gave dihydrobenzofuranols 4a-h in 68-84% yields. Similarly, irradiation of 2a-e afforded dihydrobenzofuranols 8a-e in 72-75% yields. Ethyl acrylates 9b-c were also produced in 6-8% yields from photoreactions of 2b-c. Substituent effects on cyclization of 1,5-biradical intermediates and reaction pathways are discussed. Benzophenones are useful compounds to prepare dihydrobenzofuranols by photocyclization.