Photolysis of α-aryloxy-ketones

Abstract

Irradiation of aryloxy-ketones ArO·CHR¹·COR²(R¹= H, alkyl, or Ph; R²= alkyl or Ph) in methanol caused fission of the C–OAr bond to give a phenol (ArOH), a ketone (R¹CH₂·COR²), and a product of ortho-rearrangement which cyclised during work-up to a substituted benzofuran. The benzofurans were also synthesised by cyclisation of suitable aryloxy-ketones in polyphosphoric or sulphuric acid. In a few cases, aryloxy-ketones gave the corresponding dimethyl acetals [ArO·CHR¹·C(OMe)₂R²] upon irradiation.