Alternative synthesis and novel oxidizing ability of 6,9-disubstituted cyclohepta[b]pyrimido[5,4-d]pyrrole-8(6H),10(9H)-dione derivatives

Synthesis of 6,9-disubstituted cyclohepta[b]pyrimido[5,4-d]pyrrole-8(6H),10(9H)-diones was accomplished by ring opening and ring closure sequences of 9-substituted cyclohepta[b]pyrimido[5,4-d]furan-8,10(9H)-dione derivatives induced by several amines. Furthermore, alternative synthetic methodology for compounds was also accomplished by single-step reaction of 2-chlorotropone with 6-aminouracil derivatives under mild conditions. X-ray crystal analysis of was carried out to clarify the structural characteristics. The properties of were studied by the UV–vis spectra and reduction potentials (−1.24 to −1.39 V vs Ag/AgNO3). Novel photo-induced oxidation reaction of toward some amines under aerobic conditions was carried out to give the corresponding imines in more than 100% yield [based on compounds ], suggesting the oxidation reaction occurs in an autorecycling process.