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

Temperature

0 °C

2-(5-Bromo-1H-imidazol-2-yl)-pyrrolidine-1-carboxylic acid tert-butyl ester (4 g, 12.65 mmol) was dissolved in DMF and cooled to 0° C. NaH (658 mg of 60% mineral oil dispersion, 16.45 mmol) was added and the reaction mixture was aged for 13 min before addition of SEMCl (2.7 mL, 15.18 mmol) and warming to RT. After 16 h, the reaction was quenched by water, diluted with ethyl acetate (300 mL) and washed with water and brine. The organic phase was dried over magnesium sulfate and concentrated. The crude residue was purified by silica column chromatography (10% to 30% EtOAc/hexanes) to afford 2-[5-Bromo-1-(2-trimethylsilanyl-ethoxymethyl)-1H-imidazol-2-yl]-pyrrolidine-1-carboxylic acid tert-butyl ester (4.67 g, 83%). 2-[5-Formyl-1-(2-trimethylsilanyl-ethoxymethyl)-1H-imidazol-2-yl]-pyrrolidine-1-carboxylic acid tert-butyl ester: 2-[5-Bromo-1-(2-trimethylsilanyl-ethoxymethyl)-1H-imidazol-2-yl]-pyrrolidine-1-carboxylic acid tert-butyl ester (3.804 g, 8.52 mmol) was dissolved in THF (42 mL) and cooled to −78° C. n-BuLi (3.4 mL of a 2.5 M hexane solution, 8.52 mmol) was added dropwise over 3 min. After 65 min, DMF (4 mL) was added and the reaction mixture was warmed to RT. After stirring at RT for 75 min, a saturated aqueous solution of ammonium chloride (50 mL) was added and the entire content of the flask was poured into saturated aqueous sodium bicarbonate. The aqueous phase was extracted 3 times with diethyl ether. The combined organic layers were dried over magnesium sulfate, concentrated and purified by silica column chromatography (30% to 70% EtOAc/hexanes) to provide 2-[5-Formyl-1-(2-trimethylsilanyl-ethoxymethyl)-1H-imidazol-2-yl]-pyrrolidine-1-carboxylic acid tert-butyl ester (1.50 g, 45%). 2-[5-Ethynyl-1-(2-trimethylsilanyl-ethoxymethyl)-1H-imidazol-2-yl]-pyrrolidine-1-carboxylic acid tert-butyl ester: 2-[5-Formyl-1-(2-trimethylsilanyl-ethoxymethyl)-1H-imidazol-2-yl]-pyrrolidine-1-carboxylic acid tert-butyl ester (1.625 g, 4.11 mmol) and dimethyl-1-diazo-2-oxopropylphosphonate (1.056 g, 5.50 mmol) were dissolved in 1:1 MeOH/THF (10 mL) and potassium carbonate (1.14 g, 8.25 mmol) was added. After stirring for 200 min, more potassium carbonate (1.14 g, 8.25 mmol) was added. 45 min later, the reaction mixture was poured into 100 mL 1:1 water/saturated aqueous sodium bicarbonate. The aqueous phase was extracted 3 times with diethyl ether. The combined organic phases were dried with magnesium sulfate and concentrated. The crude residue was purified by silica column chromatography (20% to 45% EtOAc/hexanes) to afford 245-Ethynyl-1-(2-trimethylsilanyl-ethoxymethyl)-1H-imidazol-2-yl]-pyrrolidine-1-carboxylic acid tert-butyl ester (1.234 g, 77%). {1-[2-(5-Ethynyl-4H-imidazol-2-yl)-pyrrolidine-1-carbonyl]-2-methyl-propyl}-carbamic acid methyl ester: 245-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%). (1-{2-[5-(4-{2-[1-(2-Methoxycarbonylamino-3-methyl-butyryl)-pyrrolidin-2-yl]-3H-imidazol-4-yl}-phenylethynyl)-1H-imidazol-2-yl]-pyrrolidine-1-carbonyl}-2-methyl-propyl)-carbamic acid methyl ester: {1-[2-(5-Ethynyl-1H-imidazol-2-yl)-pyrrolidine-1-carbonyl]-2-methyl-propyl}-carbamic acid methyl ester (46 mg, 0.144 mmol), (1-{2-[5-(4-Bromo-phenyl)-1H-imidazol-2-yl]-pyrrolidine-1-carbonyl}-2-methyl-propyl)-carbamic acid methyl ester (78 mg, 0.173 mmol), Pd(PPh3)4 (17 mg, 0.0144 mmol), CuI (5 mg, 0.0288 mmol) and triethylamine (0.200 mL, 1.44 mmol) were suspended in DMF (1.5 mL). The reaction mixture was stirred at 80° C. for 2 hours then 1 mL of water was added and the mixture was purified by reverse phase preparative HPLC, giving (1-{2-[5-(4-{2-[1-(2-Methoxycarbonylamino-3-methyl-butyryl)-pyrrolidin-2-yl]-3H-imidazol-4-yl}-phenylethynyl)-1H-imidazol-2-yl]-pyrrolidine-1-carbonyl}-2-methyl-propyl)-carbamic acid methyl ester (24 mg, 24%). 1H NMR (MeOH-d4, 400 MHz) 7.65 (d, J=8.2 hz, 2H), 7.45 (d, J=8.2 hz, 2H), 7.38 (s, 1H), 7.22 (s, 1H), 6.98 (m, 1H), 5.17 (m, 1H), 5.11 (m, 1H), 4.25-4.20 (m, 2H), 4.01-3.79 (m, 4H), 3.66 (s, 6H), 2.37-2.00 (m, 10H), 0.99-0.89 (m, 12H); MS (ESI) m/z 687 [M+H]+.

1. concentrationconcentrated
2. customThe stirred reaction mixture
3. stirringAfter stirring for 3 h
4. washwashed with a saturated aqueous solution of sodium bicarbonate and brine
5. dry with materialThe combined organic layers were dried over magnesium sulfate
6. concentrationconcentrated
7. customThe crude residue was purified by silica column chromatography (40% to 75% EtOAc/hexanes)
8. customto provide the coupled compound (741 mg, 65% over 2 steps)
9. customThe stirred reaction mixture
10. temperaturewas heated
11. temperatureto reflux for 4 h
12. temperaturecooled to RT
13. extractionThe aqueous phase was extracted 3 times with dichloromethane
14. dry with materialThe combined organic layers were dried over magnesium sulfate
15. concentrationconcentrated
16. customThe crude residue was purified by silica column chromatography (0% to 10% MeOH/DMC)

ORD record

ord-c2ddd06a5a754bd2a80a09c80e092497

Source dataset

uspto-grants-2012_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08273341B2