Heptanal → HCID 66811753, compound

Participants

Reaction Conditions

Reaction Steps

To a stirred solution of 3-[4-(2-ethylamino-ethylamino)-3-nitro-phenyl]-acrylic acid methyl ester (8.174 g, 27.87 mmol) and heptaldehyde (4.85 g, 42.47 mmol, 1.52 eq) in AcOH and MeOH (1:9 v/v, 300 mL) was added SnCl2.2H2O (31.45 g, 139.4 mmol, 5 eq) in portions. The resulting mixture was heated to 40° C. with stirring. The progress of the reaction was monitor by LC/MS. When the reaction was completed, solvent was removed under reduced pressure below 40° C. The resultant residue was diluted with EtOAc (50 mL) then basified (pH>10) with saturated aqueous Na2CO3 and extracted with dichloromethane (×3). Filtration may be needed to remove the white precipitates or suspension derived from Tin in order to get clearly separated layers. The organic extracts were combined, dried (Na2SO4), filtered, and evaporated to dryness. The resulting oily residue was purified by flash column chromatography (silica, φ67×65 mm, solvent MeOH/DCM gradient from 0 to 10%). 3-[1-(2-ethylamino-ethyl)-2-hexyl-1H-benzoimidazol-5-yl]-acrylic acid methyl ester was obtained as yellow solid (4.445 g, 44.6%). HPLC purity at 254 nm: 98.8%, tR=1.71 min. LCMS (ESI) m/z: 358 ([M+H]+). 1H NMR (CDCl3) δ 7.88 (1H, d, J=1.2 Hz), 7.83 (1H, d, J=16.0 Hz), 7.43 (1H, dd, J=8.4, 1.4 Hz), 7.33 (1H, d, J=8.4 Hz), 6.43 (1H, d, J=15.9 Hz), 4.22 (2H, t, J=6.6 Hz), 3.80 (3H, s), 3.01 (2H, t, J=6.6 Hz), 2.89 (2H, t, J=7.9 Hz), 2.65 (2H, q, J=7.1 Hz), 1.91 (2H, pentet, J=7.8 Hz), 1.46 (2H, m), 1.35 (4H, m), 1.07 (3H, t, J=7.1 Hz), 0.90 (3H, t, J=7.0 Hz). The solid could be recrystallized from Hexanes-ether to give a white or pale yellow solid with HPLC purity at 254 nm: 99.2%.

Provenance & Evidence