(3R)-1-(tert-butoxycarbonyl)-3-ethylpiperidine-3-acetic acid

1-benzyl-3-ethyl-3-cyanomethylpiperidine

3-Carboxymethyl-3-ethyl-piperidine-1-carboxylic acid benzyl ester

1-Benzyl-3-ethyl-6-oxo-piperidine-3-carboxylic acid ethyl ester

benzyl 3-ethyl-3-methoxycarbonylmethylpiperidine-1-carboxylate