中间体Ethyl (S)-nipecotate,L-tartrate (S)-3-哌啶甲酸乙酯-D酒石酸盐 83602-38-4 ≥99%中间体2-Piperidine carboxamide 2-哌啶甲酰胺中间体3-Piperidine carboxamide 3-哌啶甲酰胺 4138-26-5 ≥98%