PHOTOCYCLOADDITION OF 4-METHOXYQUINOLIN-2(1<i>H</i>)-ONE AND RELATED COMPOUNDS TO ALLENE: SYNTHESIS OF 1-METHYLENE-1,2-DIHYDROCYCLOBUTA[<i>c</i>]QUINOLIN-3(4<i>H</i>)-ONE AND RELATED COMPOUNDS
Photocycloaddition of 4-methoxy-2-pyridones and -quinolones to allene gives the head-to-tail adduct as the predominant product, which by base treatment affords the title compounds.