Studies on pyrimidine derivatives. XVI. Site selectivity in the homolytic substitution of simple pyrimidines.
作者:TAKAO SAKAMOTO、TAKEJI SAKASAI、HIROSHI YAMANAKA
DOI:10.1248/cpb.28.571
日期:——
Pyrimidine derivatives in which both the 2- and 4-positions are free exhibited site selectivity in their reactions with radicals generated in redox systems. Namely, 6-phenyl-(I), 6-methylpyrimidine (XV), and 5, 6, 7, 8-tetrahydroquinazoline (XVII) reacted with radicals such as RCO, R2NCO, EtOCO, and CH2OH to give predominantly the 4-substituted products. Except in the reaction of I with the N, N-dimethylcarbamoyl radical, the formation of the corresponding 2-substituted isomers was not observed.
在2位和4位均处于游离状态的嘧啶衍生物中,它们与在氧化还原系统中生成的自由基反应时表现出位点选择性。即,6-苯基-(I)、6-甲基嘧啶(XV)和5, 6, 7, 8-四氢喹唑啉(XVII)与诸如RCO、R2NCO、EtOCO和CH2OH等自由基反应,主要生成4位取代产物。除了I与N,N-二甲基氨基甲酰基自由基反应外,未观察到相应的2位取代异构体的形成。