Trifluoroacetic acid → 2-[(4-Ethoxyphenyl)methyl]-N,N-diethyl-1-[[(2R)-1-methyl-2-pyrrolidinyl]methyl]-1H-benzimidazole-5-carboxamide

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Reaction Steps

N-[2-Amino-5-[(diethylamino)carbonyl]phenyl]-4-ethoxy-benzeneacetamide (85 mg, 0.230 mmol) and N-(tert-butoxycarbonyl)-D-prolinal (0.06 mL, 1.5 eq) were coupled and cyclized following the procedure in example 40E. The solvent was then concentrated. The residue was dissolved in MeOH and 37% formaldehyde in water (formalin) (few drops, excess) was added, followed by sodium cyanoborohydride (43 mg, 3 eq). The solution was then stirred at rt for 1 h. The crude product was directly purified by reversed-phase chromatography (C-18 column) using a gradient of 15–65% CH3CN/H2O and then lyophilized affording the title compound (46 mg, 36% yield) as the corresponding TFA salt; 1H NMR (400 MHz, CD3OD) δ 7.80 (d, J=8.8 Hz, 1H), 7.69 (s, 1H), 7.48 (d, J=8.4 Hz, 1H), 7.22 (d, J=8.8 Hz, 2H), 6.92 (d, J=8.4 Hz, 2H), 4.85 (m, 1H), 4.66 (m, 1H), 4.49 (s, 2H), 4.01 (q, J=7.2 Hz, 2H), 3.78 (br s, 2H), 3.56 (br s, 2H), 3.27 (br s, 3H), 2.95 (s, 3H), 2.02 (m, 3H), 1.85 (m, 1H), 1.35 (t, J=7.2 Hz, 3H), 1.25 (br s, 3H), 1.11 (br s, 3H); MS (ESI) (M+H)+=449.45; Anal. Calcd for C27H36N4O2+2.4 TFA+1.1H2O: C, 51.47; H, 5.51; N, 7.55. Found: C, 51.46; H, 5.43; N, 7.67.

Provenance & Evidence