Harue Fujii

Photocycloadditions of 4-methoxy-2-pyridone to olefins and synthesis of 1,2-dihydrocyclobuta[c]pyridin-3(4H)-ones

Irradiation of 4-methoxy-2-pyridone (1) in acetone in the presence of electron-rich alkenes afforded the 3-azabicyclo[4.2.0]oct-4-en-2-ones (2a–c) as the major products, whereas photolyses in the presence of electron-deficient alkenes led to the 2-azabicyclo[4.2.0]oct-4-en-3-ones (4a, b) as the major products; base treatment of the former adducts gave rise to the novel 1,2-dihydrocyclobuta[c]pyridin-3(4H)-ones (3a–c).

Photochemical and thermal addition of methanol to 2-phenyl-3,1-benzoxazepine-5-carboxylate: reverse stereoselectivities in the two reactions

Irradiation of methyl 2-phenyl-3,1-benzoxazepine-5-carboxylate (1) in methanol affords the (Z)-isomer of methyl 3-methoxy-2-(2-benzamidophenyl) acrylate (Z)-(4) as the major addition product, while thermal reaction of methanol with (1) in the presence of triethylamine gives the (E)-isomer (E)-(4), exclusively; reasons for the observed selectivities are discussed.