Photochemical production of sugar-like interconvertible anomeric naphthopyranylhemiacetals from acenaphthylene and chloranil

Irradiation of acenaphthylene (ACN) and p-chloranil with > 420 nm light in 1,2-dichloroethane gives two interconvertible anomeric naphthopyranylhemiac etals in high yields (> 70%), whereas irradiation of ACN with other 1,3-ben zoquinones does not afford this type of products. The above products will r esult from photochemical formation of an oxetane followed by its hydration. These products an stereoselectively converted into an identical naphthopyr anylacetal in primary alcohols.