Hydrochloric Acid → {1-[2-(5-Ethynyl-1H-imidazol-2-yl)-pyrrolidine-1-carbonyl]-2-methyl-propyl}-carbamic acid methyl ester

Participants

Reaction Conditions

Reaction Steps

2-[5-Ethynyl-1-(2-trimethylsilanyl-ethoxymethyl)-1H-imidazol-2-yl]-pyrrolidine-1-carboxylic acid tert-butyl ester (1.002 g, 2.56 mmol) was dissolved in dioxane (5 mL) and 4 M HCl in dioxane (5 mL) was added. The reaction mixture was stirred for 3 hours and concentrated. To the residue was added 2-Methoxycarbonylamino-3-methyl-butyric acid (561 mg, 3.20 mmol), HATU (1.22 g, 3.20 mmol) and DMF (15 mL). The stirred reaction mixture was cooled to 0° C. and DIPEA (2.23 mL, 12.8 mmol) was added). After stirring for 3 h, the reaction mixture was diluted with ethyl acetate and washed with a saturated aqueous solution of sodium bicarbonate and brine. The combined organic layers were dried over magnesium sulfate and concentrated. The crude residue was purified by silica column chromatography (40% to 75% EtOAc/hexanes) to provide the coupled compound (741 mg, 65% over 2 steps). This material was dissolved in dichloromethane (10 mL) and trifluoroacetic acid (5 mL) was added. The stirred reaction mixture was heated to reflux for 4 h, then cooled to RT, and poured into a saturated aqueous solution of sodium bicarbonate. The aqueous phase was extracted 3 times with dichloromethane. The combined organic layers were dried over magnesium sulfate and concentrated. The crude residue was purified by silica column chromatography (0% to 10% MeOH/DMC) to provide {1-[2-(5-Ethynyl-1H-imidazol-2-yl)-pyrrolidine-1-carbonyl]-2-methyl-propyl}-carbamic acid methyl ester (525 mg, 100%).

Provenance & Evidence