反应详情

To a mixture of tert-butyl 1-(2-hydroxy-2-(4-(N′-hydroxycarbamimidoyl)phenyl)ethyl)azetidine-3-carboxylate (111 mg, 0.33 mmol) and DIEA (0.115 mL, 0.660 mmol) in acetonitrile (10 mL) was added 3-phenyl-4-(trifluoromethyl)isoxazole-5-carbonyl fluoride, Int-I-G (86 mg, 0.33 mmol). After 1 hour, TBAF (0.330 mL, 0.330 mmol) was added and the reaction was stirred overnight. The reaction mixture was diluted with ethyl acetate and washed with H2O. The organic layer was dried with MgSO4, filtered, and concentrated. Crude residue was treated with TFA/DCM to remove t-butyl ester. The resulting material was concentrated in vacuo and purified by HPLC to yield 36 mg of 1-(2-hydroxy-2-(4-(5-(3-phenyl-4-(trifluoromethyl)isoxazol-5-yl)-1,2,4-oxadiazol-3-yl)phenyl)ethyl)azetidine-3-carboxylic acid as the tetrabutylammonium salt. 1H NMR (400 MHz, MeOH-d3) δ ppm 8.22 (2H, d, J=8.35 Hz), 7.68 (4H, d, J=8.35 Hz), 7.53-7.65 (3H, m), 5.04 (1H, dd, J=10.11, 3.08 Hz), 4.45 (4H, t, J=9.89 Hz), 3.73 (1H, br. s.), 3.36-3.62 (2H, m). MS (m+1)=501. HPLC Peak RT=3.23 minutes (Analytical Method A). Purity=98%.

1. washwashed with H2O
2. dry with materialThe organic layer was dried with MgSO4
3. filtrationfiltered
4. concentrationconcentrated
5. additionCrude residue was treated with TFA/DCM
6. customto remove t-butyl ester
7. concentrationThe resulting material was concentrated in vacuo
8. custompurified by HPLC