Intramolecular Cycloadditions of Photogenerated Azaxylyleneswith Oxadiazoles Provide Direct Access to Versatile PolyheterocyclicKetopiperazines Containing a Spiro-oxirane Moiety.

Photogeneratedazaxylylenes undergo intramolecular cycloadditionsto 1,3,4-oxadiazole pendants, which are accompanied by concomitantrelease of dinitrogen, yielding functionalized ketopiperazinoquinolinolscontaining an oxirane moiety fused to the quinolinole moiety whilespiro-connected to diketopiperazine. These primary photoproducts arereactive versatile intermediates which can be further derivatizedunder nucleophilic SN1- or SN2-like ring openingof the oxirane moiety. The oxidized quinolinones undergo new rearrangementsunder the conditions of the Schmidt reaction, leading to unprecedentedtriazacanoindolinones. [ABSTRACT FROM AUTHOR]