Synthesis of Imido-Substituted 3,8-Diphenyl-1,2-diazacycloocta-2,4,6,8-tetraenes and Their Thermolysis

Article abstract of DOI:10.1246/bcsj.60.731

Nucleophilic substitution of 4,7-dichloro-3,8-diphenyl-1,2-diazociane with succinimide, phthalimide, N-methyl-p-toluenesulfonamide, and o-benzosulfimide, in the presence of silver oxide, gave the corresponding 4-mono(imido)- and 4,7-di(imido)-1,2-diazocines. 4-Acetoxy-7-phthalimido- and 4-phenylthio-7-phthalimido-1,2-diazocine were also prepared.Thermolysis of the mono(imido)-1,2-diazocines in xylene under reflux afforded the corresponding di(imido)-1,2-diazocine and/or five pyridine derivatives, whose relative yields depended upon the nature of imido substitutents in the diazocines.However, 4,7-di(imido)-1,2-diazocines did not decompose in xylene under reflux.Thermolysis of 4,7-bis(phthalimido)-1,2-diazocine at 300-310 deg C gave 3,6-bis(phthalimido)-2-phenylpyridine with the extrusion of benzonitrile.In the thermolysis of the acetoxy- (230-240 deg C) or phenylthio-substituted 1,2-diazocine (240-260 deg C), 6-acetoxy- and 6-benzoyl-3-phthalimido-2-phenylpyridine, or 6(and 3)-phenylthio-3(and 6)-phthalimido-2-phenylpyridines were isolated together with benzonitrile, respectively.The feature of thermolysis was also discussed.