1-phenylhexahydropyrimidines and 3-isopropyl- and 3-phenyl-1,2,3,4-tetrahydroquinazolines proved to be ring-chain tautomeric mixtures in CDCl3 at 300 K, whereas only ring-closed tautomers could be detected for the 1- or 3-methyl-substituted analogues. The ratios of the ring-chain tautomeric forms at equilibrium could be described by the equation
在300 K的CDCl 3中,2-Aryl取代的1-异丙基和1-苯基六氢
嘧啶以及3-异丙基和3-苯基-1,2,3,4-四氢
喹唑啉是环链互变异构混合物,而仅可以检测到1-或3-甲基取代的类似物的闭环互变异构体。平衡状态下的环链互变异构形式的比率可用以下方程式描述