3-[2-(1-benzyloxycarbonyl-4-piperidyl)ethylthio]-2(S)-hydroxypropionic acid 、
3-[2-(1-benzyloxycarbonyl-4-piperidyl)-ethoxy]-2(R)-hydroxypropionic acid 以to give 2.0 g of oily ethyl 3-[2-(1-benzyloxycarbonyl-4-piperidyl)ethylthio]-2(S)-hydroxypropionate的产率得到ethyl 3-[2-(1-benzyloxycarbonyl-4-piperidyl)ethylthio]-2(S)-hydroxypropionate