ethyl 4-<4'-<<2-<(tert-butoxycarbonyl)amino>-2-carboxy>ethyl>phenoxy>butanoate

辛酸乙酯

4-巯基丁酸

4-(4-甲酰基苯基)丁酸乙酯

4-(4-乙酰基-2-甲氧基苯氧基)-丁酸乙酯