ethyl 3-hydroxy-3,6-dihydro-2H-pyridine-1-carboxylate

1-carboethoxy-3-methoxy-5-oxo-3,4-dehydropiperidine

1-benzylpiperidine-3,5-dione,hydrochloride

1-benzyl-3-methoxy-5-oxo-3,4-dehydropiperidine

1-苄基-3,5-哌啶二酮