ethyl cis(3H,4H)-1-benzoyl-3-(2-oxoethyl)piperidine-4-acetate

benzyl 5-(1,3-dioxolan-2-ylmethyl)-3,4-epoxypiperidine-1-carboxylate

benzyl 3-(1,3-dioxolan-2-ylmethyl)-4-oxopiperidine-1-carboxylate

(3R,4S)-4-Ethoxycarbonylmethyl-3-(2-oxo-ethyl)-piperidine-1-carboxylic acid benzyl ester