Water → (2-{1-[2-(2,5-Dimethyl-phenyl)-acetyl]-piperidin-4-yl}-thiazol-4-yl)-carbamic acid tert-butyl ester

Participants

Reaction Steps

To a solution of 2-{1-[2-(2,5-dimethyl-phenyl)-acetyl]-piperidin-4-yl}-thiazole-4-carboxylic acid (5.65 g, 15.76 mmol) in tert-butanol (60 mL) is added triethylamine (5.2 mL, 36.2 mmol). After stirring 30 min. at RT, diphenylphosphoryl azide (6.9 mL, 31.5 mmol) is added and the reaction mixture is divided in 4 portions and each portion is irradiated under microwave (100° C., 15 min.). After cooling to RT, all portions are combined and water (1 mL) is added to the reaction mixture and stirred for 30 minutes. Acetonitrile (50 mL) is then added, followed by addition of basic Amberlyst A21. After stirring overnight at RT, the resin is filtered off, and solvents are evaporated under reduced pressure. The remainder is purified by column chromatography on silica gel (ethyl acetate/cyclohexane 7:3) to give (2-{1-[2-(2,5-dimethyl-phenyl)-acetyl]-piperidin-4-yl}-thiazol-4-yl)-carbamic acid tert-butyl ester (4.93 g, 73%). 1H-NMR (400 MHz, CDCl3): δ=1.53 (s, 9H), 1.53-1.61 (m, 1H), 1.67-1.79 (m, 1H), 1.95-2.04 (m, 1H), 2.08-2.14 (m, 1H), 2.25 (s, 3H), 2.30 (s, 3H), 2.80-2.90 (m, 1H), 3.06-3.20 (m, 2H), 3.68 (s, 2H), 3.80-3.89 (m, 1H), 4.68-4.74 (m, 1H), 6.95 (s, 1H), 6.98 (d, 1H), 7.07 (d, 1H), 7.23 (s, 1H). MS: m/z=430 (M+1).

Provenance & Evidence