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[摘要]：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-Buchi reaction)-oxetene electrocyclic ring opening-hexatriene to phenanthrene type electrocyclization-oxidative dehydrogenation. Using these photo tandem reactions of isoquinolinetrione with acetylenes substituted by different azaaryl rings including pyridine, pyrimidine, pyrazine, and quinoline, we were able to obtain diverse aza-polycyclic frameworks with isoquinolinedione fused with naphthalene, quinoline or isoquinoline, quinazoline, quinoxaline, and phenanthridine, respectively, with yields up to 85%. Regioselectivity of the [2 + 2] photocycloadditions and the electrocyclization reactions in the reaction sequence that leads to the formation of different aza-polycyclic ring systems is discussed. Changing the other substitution group on the azaaryl substituted acetylenes from benzene to pyridine or cyclopropane resulted in acetylenes with different photoreactivities with isoquinolinetrione and improved regioselectivity to form single aza-polycyclic products. |
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