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

Abstract

Synthesis of 6,9-disubstituted cyclohepta[ b]pyrimido[5,4- d]pyrrole-8(6 H),10(9 H)-diones 7a– g was accomplished by ring opening and ring closure sequences of 9-substituted cyclohepta[ b]pyrimido[5,4- d]furan-8,10(9 H)-dione derivatives induced by several amines. Furthermore, alternative synthetic methodology for compounds 7a– e was also accomplished by single-step reaction of 2-chlorotropone with 6-aminouracil derivatives under mild conditions. X-ray crystal analysis of 7a was carried out to clarify the structural characteristics. The properties of 7a– e were studied by the UV–vis spectra and reduction potentials (−1.24 to −1.39 V vs Ag/AgNO 3). Novel photo-induced oxidation reaction of 7a– d toward some amines under aerobic conditions was carried out to give the corresponding imines in more than 100% yield [based on compounds 7a– d ], suggesting the oxidation reaction occurs in an autorecycling process.