Hydrochloric Acid → HCID 68502775, compound

Participants

Reaction Conditions

Reaction Steps

Trans-methyl 2-(3,5-difluorobenzyl)-4-(3-ethoxy-3-oxopropanoyl)piperidine-1-carboxylate (0.927 g, 2.42 mmol) (from example 130, step 1) was dissolved in MeOH (8 mL) and cooled to −40° C. under nitrogen atmosphere. Sodium hydroxide (0.097 g, 2.42 mmol) dissolved in water (0.800 mL) was added over 7 min. After 20 min with stirring, hydroxylamine (50% by weight in water, 0.148 mL, 2.42 mmol) was added over 4.5 minutes and the solution was stirred for 3.5 hours at −40° C. The reaction mixture was then rapidly poured into a prewarmed (80° C.) solution of 6 M hydrogen chloride (12.45 mL, 74.71 mmol) and the mixture continued to stir at 80° C. for 20 min. The solvent was evaporated and the crude mixture redissolved in DCM and washed with water. The organic phase was dried and concentrated. The compound was purified by preparative HPLC on a XBridge C18 column (10 μm 250×50 ID mm) using a gradient of 0-25% Acetonitrile in H2O/MeCN/NH3 95/5/0.2 buffer over 20 minutes with a flow of 100 mL/min. Trans-methyl 2-(3,5-difluorobenzyl)-4-(3-oxo-2,3-dihydroisoxazol-5-yl)piperidine-1-carboxylate (0.648 g, 76%) was isolated as a white solid. 1H NMR (400 MHz, cd3od) δ 1.45-2.12 (m, 4H), 2.80-3.35 (m, 4H), 3.35-3.70 (m, 3H), 4.12 (s, br., 1H), 4.62 (s, br., 1H), 5.71 (s, 1H), 6.77 (t, 1H), 6.87 (s, br., 2H). MS m/z 353 (M+H)+

Provenance & Evidence