反应详情

A solution of N-(2-benzoyl-4-chlorophenyl)trifluoromethanesulfonamide 25 (710 mg, 1.95 mmol), O-(3,4-dichlorobenzyl)hydroxylamine hydrochloride (468 .mg, 2.05 mmol) and anhydrous NaOAc (168 mg, 2.05 mmol) in EtOH (50 mL) was stirred for 15 hours at RT. The reaction mixture was concentrated under vacuum, the residue filtered through a pad of silica (eluting with CH2Cl2/PE, 3:2) and the solvent removed under reduced pressure. An isomeric mixture of E- and Z-oxime ether derivatives was obtained, which were separated by radial thin layer chromatography (eluting with CH2Cl2/PE, 7.5:92.5 to 1:5). The major isomer was obtained as a pale yellow solid which was recrystallized from CH2Cl2/PE to give N-{4-chloro-2-[(3,4-dichlorobenzyloxyimino)phenylmethyl]phenyl}trifluoromethanesulfonamide 87 (535 mg, 51%), as pale yellow crystals. M.p. 87-88° C. 1H n.m.r. (200 MHz, CDCl3) δ 11.18, br s, 1H; 7.65, d, J=8.8 Hz, 1H; 7.55-7.40, m, 5H; 7.34-7.14, m, 4H; 6.88, d, J=2.2 Hz, 1H; 5.09, s, 2H. The minor isomer was obtained as a pale yellow solid (315 mg, 30%).

1. concentrationThe reaction mixture was concentrated under vacuum
2. filtrationthe residue filtered through a pad of silica (eluting with CH2Cl2/PE, 3:2)
3. customthe solvent removed under reduced pressure
4. additionAn isomeric mixture of E- and Z-oxime ether derivatives
5. customwas obtained
6. customwhich were separated by radial thin layer chromatography (eluting with CH2Cl2/PE, 7.5:92.5 to 1:5)
7. customThe major isomer was obtained as a pale yellow solid which
8. customwas recrystallized from CH2Cl2/PE