Hydroxylamine → tert-butyl 2-methyl-4-[(5S)-5-(3,4,5-trichlorophenyl)-5-(trifluoromethyl)-4H-isoxazol-3-yl]benzoate

Participants

Reaction Conditions

Reaction Steps

A 1500 mL reaction-vessel was charged at RT with 1-Anthracen-9-ylmethyl quininium chloride 13.77 mmol, 7.59 g) and tert-butyl 2-methyl-4-[(Z)-4,4,4-trifluoro-3-(3,4,5-trichlorophenyl)but-2-enoyl]benzoate (68.87 mmol, 34 g) and dissolved in chloroform (700 mL). The mixture cooled down to −30° C. Then, a solution of hydroxylamine (50 mass % in H2O, 9.1 g) in water (50.9 mL) and cesium hydroxide hydrate (185.9 mmol, 32.88 g) in water (60 mL) were added simultaneously dropwise to the reaction mixture over 30 min. After the addition the reaction was kept 16 h at −30° C. after which time the conversion was complete. The reaction was brought to room temperature diluted with dichloromethane and washed three times with water. The organic phase was dried over MgSO4 and evaporated to yield crude title product. The product was purified over a silica gel column (eluent: EtOAc/Heptane) to obtain 39.0 g of the title product. LCMS (Method GR): RT 1.44 min, no ionisation: 1H NMR (400 MHz, CDCl3) 16.0 (s, 9H), 2.60 (s, 3H), 3.70 (d, 1H), 4.10-4.20 (m, 2H), 7.25-7.90 (m, 5H), 19F-NMR (CDCl3, 376 MHz): −79.40.

Provenance & Evidence