Photoinduced tandem reactions of isoquinoline-1,3,4-triones (3) with azaaryl substituted acetylenes (4a−4o) are described as an efficient method to build novel aza-polycycles. Most of the reactions proceeded via the tandem reaction sequence of photoinduced [2 + 2] cycloaddition (the Paterno−Büchi reaction)-oxetene electrocyclic ring opening-hexatriene to phenanthrene type electrocyclization-oxidative