cis-5-methyl-4,5-dicarbomethoxy-2-oxazoline

trans-5-methyl-4,5-dicarbomethoxy-2-oxazoline

(S)-(-)-3-羟基-3-甲基-4,4,4-三氯丁酸-beta-内酯

4-乙氧基-2-亚甲基-4-氧代丁酸