Sodium Hydroxide → 3-(4-Chlorobenzo[b]thiophen-2-yl)-5-(3,5-dichlorophenyl)-5-(trifluoromethyl)-4,5-dihydroisoxazole

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Reaction Steps

Stir a mixture of 1-(4-chlorobenzo[b]thiophen-2-yl)-3-(3,5-dichlorophenyl)-4,4,4-trifluorobut-2-en-1-one (1.05 g, crude, 2.43 mmol), NaOH (389 mg, 9.72 mmol) and NH2OH—HCl (335 mg, 4.8 mmol) in MeOH (8 mL) and water (8 mL) at ambient temperature for 4 hours. After removal of solvent under vacuum, dilute the residue with ice water (20 mL). Extract the aqueous mixture with EtOAc (15 mL×3). The combined organic layers are washed with brine, dried over anhydrous Na2SO4 and concentrated under vacuum. Purify the residue by preparative HPLC to afford 3-(4-chlorobenzo[b]thiophen-2-yl)-5-(3,5-dichlorophenyl)-5-(trifluoromethyl)-4,5-dihydroisoxazole as white solid (305 mg, 28.1%). MS (m/z): 450 (M+1). 1H NMR (400 MHz, CDCl3) δδ 7.74 (d, J=8.0, 1H), 7.64-7.60 (s, 1H), 7.57-7.53 (m, 2H), 7.47-7.43 (m, 1H), 7.40-7.32.

Provenance & Evidence