Hydrochloric Acid → 3,3-bis(fluoromethyl)-5-(5-(3,4,5-trichlorophenyl)-5-(trifluoromethyl)-4,5-dihydro-isoxazol-3-yl)benzo[c][1,2]oxaborol-1(3H)-ol

Participants

Reaction Conditions

Reaction Steps

To a solution of (E)-3,3-bis(fluoromethyl)-1-hydroxy-1,3-dihydrobenzo[c][1,2]oxaborole-5-carbaldehyde oxime (440 mg, 1.83 mmol) in DMF (10 mL) at rt was added NCS (294 mg, 2.19 mmol). The reaction mixture was warmed to 45° C., stirred for 2.5 h and cooled to rt. To a solution of 1,2,3-trichloro-5-(3,3,3-trifluoroprop-1-en-2-yl)benzene (577 mg, 2.10 mmol) and TEA (403 mg, 4.0 mmol) in DMF (10 mL) was added the above mixture dropwise at 0° C. The mixture was stirred at 0° C. for 1 h, then stirred at rt overnight. The mixture was acidified with HCl (3 N) to pH of 2, then poured into water and extracted with EA (50 mL×2). The combined organic layers were washed with brine, dried over Na2SO4, filtered and concentrated under reduced pressure. The residue was purified by prep-TLC (PE:EA=2:1) to give the final title compound (150 mg, 16%) as white solid. 1H NMR (300 MHz, DMSO-d6): δ 9.74 (s, 1H), 7.96-7.80 (m, 5H), 4.89-4.80 (m, 2H), 4.73-4.64 (m, 2H), 4.46 (d, J=17.4 Hz, 1H), 4.35 (d, J=17.4 Hz, 1H) ppm; HPLC purity: 95.3% at 214 nm; MS: m/z=516 (M+1, ESI+).

Provenance & Evidence