反应详情

To a solution of tert-butyl 1-(4-(N′-(4-phenyl-5-(trifluoromethyl)thiophene-2-carbonyloxy)carbamimidoyl)benzyl)azetidine-3-carboxylate (744 mg, 1.33 mmol) in acetonitrile (30 mL) was added a 1M solution of TBAF in tetrahydrofuran (3.99 mL, 3.99 mmol), and the reaction mixture was allowed to stir at room temperature for 3 days. The volatiles were removed under reduced pressure, and the residue was chromatographed on a 5×12 cm silica gel column, eluting with a 0-50% EtOAc/Hex gradient. The essentially pure fractions containing product were concentrated to afford tert-butyl 1-(4-(5-(4-phenyl-5-(trifluoromethyl)thiophen-2-yl)-1,2,4-oxadiazol-3-yl)benzyl)azetidine-3-carboxylate (521 mg, 0.962 mmol, 72.4% yield) as a colorless solid. HPLC ret. time=3.63 min. (YMC Combi S-5 4.6×50 mm ODS column) eluting with 10-90% aqueous methanol+0.2% phosphoric acid over a 4 minute gradient. MS: (M+H)=542.22. 1H NMR (500 MHz, CDCL3) δ ppm 1.46 (s, 9H), 3.25-3.31 (m, 3H), 3.52-3.58 (m, 2H), 3.69 (s, 2H), 7.43 (d, J=8.25 Hz, 2H), 7.47 (m, 5H), 7.91 (s, d, J=1.65 Hz, 1H), and 8.09 (d, J=8.25 Hz, 2H).

1. customThe volatiles were removed under reduced pressure
2. customthe residue was chromatographed on a 5×12 cm silica gel column
3. washeluting with a 0-50% EtOAc/Hex gradient
4. additionThe essentially pure fractions containing product
5. concentrationwere concentrated