Photocyclization reactions. Part 5. Synthesis of dihydrobenzofuranols using photocyclization of 2??alkoxybenzophenones and ethyl 2??benzoylphenoxyacetates
Abstract 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 ...