Ammonia → (1H-Benzoimidazol-5-yl)-(cis-2,3,4a,5,6,10b-hexahydro-1H-benzo[f]quinolin-4-yl)-methanone

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Reaction Steps

2-(1H-Benzotriazol-1-yl)-1,1,3,3-tetramethyluronium tetrafluoroborate (0.50 g; alternatively, 2-(7-aza-1H-benzotriazol-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate may be used) is added to a solution of 1H-benzoimidazole-5-carboxylic acid (0.23 g) and ethyl-diisopropyl-amine (0.50 mL) in N,N-dimethylformamide (2 mL) at room temperature. The solution is stirred for 20 min prior to the addition of cis-1,2,3,4,4a,5,6,10b-octahydro-benzo[f]quinoline (0.30 g) dissolved in N,N-dimethylformamide (2 mL). The resulting solution is stirred at room temperature for 3 h. 32% aqueous ammonia (1 mL) in methanol (2 mL) is then added and the mixture is stirred for another 30 min. The mixture is diluted with ethyl acetate and washed with water and brine and dried (Na2SO4). The solvent is evaporated and the residue is chromatographed on silica gel (dichloromethane/methanol containing 1% NH3 95:5→80:20) to afford the title compound as a foam-like solid that is triturated with ether and dried to give a colorless solid [alternatively, the product may be purified by HPLC on reversed phase (MeOH/H2O)]. Yield: 0.38 g (80% of theory); LC (method 1): tR=2.53 min; Mass spectrum (ESI+): m/z=332 [M+H]+; 1H NMR (400 MHz, DMSO-d6, mixture of 2 rotamers) δ 1.52-1.82 (m, 4H), 1.82-1.94 (m, 1H), 2.24-ca. 2.48 (m, 1.5H), 2.71-3.02 (m, 3H), 3.03-3.18 (m, 0.5H), 3.50-3.65 (m, 0.5H), 3.88-4.05 (m, 0.5H), 4.39-4.56 (m, 0.5H), 4.83-4.99 (m, 0.5H), 6.89-7.20 (m, 4H), 7.21-7.27 (m, 1H), 7.56-7.70 (m, 2H), 8.23-8.35 (m, 1H), 12.58 (broad s, 1H).

Provenance & Evidence