4-(4-Carboxy-thiophen-2-yl)-piperidine-1-carboxylic acid t-butyl ester (0.1 g, 0.32 mmol) was dissolved in acetonitrile (2 mL). Triethylamine (0.96 mmol), HATU (0.35 mmol) and decahydroquinoline (3:2 mixture of cis/trans-isomers; 2.5 mmol) were added and the reaction stirred at room temperature for 3 hours. The solvent was evaporated and the residue product was purified by flash chromatography on silica, eluting with 0-50% ethyl acetate in cyclohexane. The fractions containing the desired product were concentrated under vacuum to give the title compound (0.14 g). 1H NMR (400 MHz, CHCl3-d): δ 7.2 (s, 1H), 6.85 (s, 1H), 4.7 (m, 1H), 4.2 (m, 2H), 3.7 (m, 1H), 3.1-2.7 (m, 4H), 2.0-1.4 (m, 26H).
