Novel cycloadditions of isoquinoline Reissert salts

Abstract

Isoquinoline Reissert salts 5 partake in novel cycloadditions with acetylenic aldehydes 11 giving novel oxazoles 14 which have been characterised by X-ray crystallography. In contrast, closely related phthalazine Reissert salts 6 and phenanthridine Reissert salts 15 react by an alternative pathway giving pyrrolo[2,1-a]phthalazines 12 and pyrrolo[1,2-f]phenanthridines 16 respectively.