(2S,4R)-4-(2,2-diphenylacetyl)-4-(methyl(3-phenylprop-2-yn-1-yl)amino)piperidine-2-carboxylic acid

methyl (2S,4R)-1-(2,2-diphenylacetyl)-4-(methyl(3-phenylprop-2-yn-1-yl)amino)piperidine-2-carboxylate

(2S,4R)-1-(2,2-diphenylacetyl)-4-[methyl(2-phenylethyl)amino]piperidine-2-carboxylic acid

methyl (2S,4R)-4-(benzyl(methyl)amino)-1-(2,2-diphenylacetyl)piperidine-2-carboxylate

methyl (2S,4R)-1-(2,2-diphenylacetyl)-4-(methyl(phenethyl)amino)piperidine-2-carboxylate