Nitrogen → (2-methyl-1-{2-[5-(4-trimethylsilanylethynyl-phenyl)-1H-imidazol-2-yl]-pyrrolidine-1-carbonyl}-propyl)-carbamic acid methyl ester

Participants

Reaction Conditions

Reaction Steps

A solution of (1-{2-[5-(4-bromo-phenyl)-1H-imidazol-2-yl]-pyrrolidine-1-carbonyl}-2-methyl-propyl)-carbamic acid methyl ester (5.00 g, 11.1 mmol), TMS-acetylene (7.90 mL, 55.5 mmol) and triethylamine (4.64 mL, 33.3 mmol) in DMF (56 mL) was degassed with N2 gas for 20 minutes. To the degassed solution was added Pd(PPh3)4 (1.28 g, 1.11 mmol) and CuI (106 mg, 0.56 mmol). The pressure flask was sealed then heated at 80° C. overnight. After cooling to room temperature, the reaction was concentrated then diluted with EtOAc and washed with water. The aqueous phase was back-extracted two times then the organic phases were combined and dried over Na2SO4. After concentration, the crude material was purified by silica gel chromatography (10-80% EtOAc-hexanes gradient) to afford (2-methyl-1-{2-[5-(4-trimethylsilanylethynyl-phenyl)-1H-imidazol-2-yl]-pyrrolidine-1-carbonyl}-propyl)-carbamic acid methyl ester (3.08 g, 6.60 mmol, 59% yield). LCMS-ESI+: calc'd for C25H35N4O3Si: 467.3 (M+H+). Found: 467.1 (M+H+). (1-{2-[5-(4-Ethynyl-phenyl)-1H-imidazol-2-yl]-pyrrolidine-1-carbonyl}-2-methyl-propyl)-carbamic acid methyl ester: To (2-methyl-1-{2-[5-(4-trimethylsilanylethynyl-phenyl)-1H-imidazol-2-yl]-pyrrolidine-1-carbonyl}-propyl)-carbamic acid methyl ester (3.08 g, 6.60 mmol) in MeOH was added K2CO3 (1.82 g, 13.2 mmol). After stirring for 5 h, the reaction was filtered then concentrated. The residue was diluted with EtOAc then washed with H2O. The aqueous phase was back-extracted with EtOAc two times then the organic phases were combined, washed with brine, dried over Na2SO4, and concentrated. The crude material was purified by silica gel chromatography (5-10% MeOH—CH2Cl2 gradient) to afford (1-{2-[5-(4-ethynyl-phenyl)-1H-imidazol-2-yl]-pyrrolidine-1-carbonyl}-2-methyl-propyl)-carbamic acid methyl ester (2.62 g, 6.6 mmol, quantitative yield). LCMS-ESI+: calc'd for C22H27N4O3: 395.2 (M+H+). Found: 395.2 (M+H+). [1-(2-{5-[4-(4-{2-[1-(2-Methoxycarbonylamino-3-methyl-butyryl)-pyrrolidin-2-yl]-3H-imidazol-4-yl}-phenylethynyl)-phenyl]-1H-imidazol-2-yl}-pyrrolidine-1-carbonyl)-2-methyl-propyl]-carbamic acid methyl ester: A solution of (1-{2-[5-(4-bromo-phenyl)-1H-imidazol-2-yl]-pyrrolidine-1-carbonyl}-2-methyl-propyl)-carbamic acid methyl ester (947 mg, 2.11 mmol), (1-{2-[5-(4-ethynyl-phenyl)-1H-imidazol-2-yl]-pyrrolidine-1-carbonyl}-2-methyl-propyl)-carbamic acid methyl ester (1.00 g, 2.53 mmol), and triethylamine (882 μl, 6.33 mmol) in DMF (13 mL) was degassed with N2 gas for 20 minutes. To the degassed solution was added Pd(PPh3)4 (244 mg, 0.21 mmol) and CuI (40 mg, 0.21 mmol). The pressure flask was sealed then heated at 80° C. overnight. After cooling to room temperature, the reaction was concentrated then diluted with EtOAc and washed with water. The aqueous phase was back-extracted two times then the organic phases were combined and dried over Na2SO4. After concentration, the crude material was purified by silica gel chromatography (0-20% MeOH-EtOAc gradient) then reverse phase preparative HPLC (10-85% MeCN—H2O; 0.1% formic acid modifier) to afford [1-(2-{5-[4-(4-{2-[1-(2-methoxycarbonylamino-3-methyl-butyryl)-pyrrolidin-2-yl]-3H-imidazol-4-yl}-phenylethynyl)-phenyl]-1H-imidazol-2-yl}-pyrrolidine-1-carbonyl)-2-methyl-propyl]-carbamic acid methyl ester (600 mg, 1.00 mmol, 47% yield). 1H-NMR: 400 MHz, (DMSO-d6) δ: 11.84 (s, 2H), 7.75 (d, 4H), (7.56 (s, 2H), 7.47 (d, 4H), 7.28 (d, 2H), 5.06 (m, 2H), 4.06-4.04 (m, 2H), 3.80 (m, 4H), 3.54 (s, 6H), 2.14 (m, 4H) 2.00-1.90 (m, 6H), 0.89 (d, 6H), 0.84 (d, 6H). LCMS-ESI+: calc'd for C42H51N8O6: 763.4 (M+H+). Found: 763.4 (M+H+).

Provenance & Evidence