The base-catalysed cyclisation to the hydantoin of 2,2,3-trimethyl-5-phenylhydantoate (2; R1= R2= Me) is slower than that of the 2,3-dimethyl compound, even though the acceleration expected from the gem-dimethyl effect is observed for the acid-catalysed reaction.
碱催化的2,2,3-三甲基-5-苯基乙内酰
脲(2 ; R 1 = R 2 = Me)的乙内酰
脲环化反应比2,3-二甲基化合物的环化反应慢,尽管在酸催化的反应中观察到了宝石二甲基效应。