3-azetidinecarboxylic Acid → 1-((3-(2-(1-(4-Fluorophenyl)cyclohexyl)ethyl)-4,5-dihydronaphtho[1,2-c]isoxazol-7-yl)methyl)azetidine-3-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

To a solution of the 3-(2-(1-(4-fluorophenyl)cyclohexyl)ethyl)-4,5-dihydronaphtho[1,2-c]isoxazole-7-carbaldehyde (Preparation 26C, 89 mg, 0.22 mmol) and the azetidine-3-carboxylic acid (26.7 mg, 0.264 mmol) in methanol (1.5 mL) and dichloroethane (1.5 mL) at room temperature was added 4 to 5 drops of glacial acetic acid. The reaction mixture was heated at 60° C. for 1 hr, cooled to room temperature, and then treated with sodium cyanoborohydride (16.59 mg, 0.264 mmol). The reaction was stirred overnight at room temperature, quenched with ˜1 ml of saturated. aq. sodium bicarbonate, stirred for 30 min, concentrated under reduced pressure and partitioned between dichloromethane and water. The organic layer was washed with brine, dried over anhyd. sodium sulfate, concentrated, dried in vacuo and purified by preparative HPLC using the following conditions: Column. Waters XBridge C18, 19×250 mm, 5-μm particles; Guard Column: Waters XBridge C18, 19×10 mm, 5-μm particles; Mobile Phase A: 5:95 methanol:water with 10-mM ammonium acetate; Mobile Phase B: 95:5 methanol:water with 10-mM ammonium acetate; Gradient: 50-100% B over 25 minutes, then a 5-minute hold at 100% B; Flow: 20 mL/min. Fractions containing the desired product were combined and dried via centrifugal evaporation. The material was further purified via preparative LC/MS with the following conditions: Column: Waters XBridge C18, 19×250 mm, 5-μm particles; Guard Column: Waters XBridge C18, 19×10 mm, 5-μm particles; Mobile Phase A: 5:95 acetonitrile:water with 10-mM ammonium acetate; Mobile Phase B: 95:5 acetonitrile:water with 10-mM ammonium acetate; Gradient: 30-100% B over 25 minutes, then a 5-minute hold at 100% B; Flow: 20 mL/min. Fractions containing the desired product were combined and dried via centrifugal evaporation.) to yield 4.5 mgs (4.14% over three steps) of 1-((3-(2-(1-(4-fluorophenyl)cyclohexyl)ethyl)-4,5-dihydronaphtho[1,2-c]isoxazol-7-yl)methyl)azetidine-3-carboxylic acid. The compound had a HPLC retention time=2.53 min. (condition F); LC/MS M+1=489.16; 1H NMR (400 MHz, MeOD) δ ppm 7.84 (1H, d, J=7.78 Hz), 7.36-7.44 (4H, m), 7.05 (2H, t, J=8.78 Hz), 4.34 (2H, s), 4.19 (2H, s), 4.17 (2H, s), 3.42 (1H, quin, J=8.34 Hz), 2.91 (2H, t, J=7.15 Hz), 2.51 (2H, t, J=7.15 Hz), 2.38-2.45 (2H, m), 2.14 (2H, br. s.), 1.92-1.99 (2H, m), 1.35-1.70 (8H, m).

Provenance & Evidence