Hydrogen Peroxide → 2-(Bromomethyl)-3-(2-chlorophenyl)-2-(2,4-difluorophenyl)oxirane

Participants

Reaction Conditions

Reaction Steps

Maleic anhydride (2.05 g, 20.9 mmol) and then hydrogen peroxide (35% by weight strength solution, 2.04 g, 20.9 mmol) were added to a stirred solution of 1-[3-bromo-1-(2-chlorophenyl)prop-1-en-2-yl]-2,4-difluorobenzene (720 mg, 2.09 mmol) in acetic acid (20 ml). The reaction mixture was stirred at 40° C. for 24 h, more hydrogen peroxide (35% by weight strength solution, 2.04 g, 20.9 mmol) was then added and the reaction mixture was stirred at 20° C. for 66 h. Excess oxidizing agent was quenched by addition of sat. aq. sodium thiosulphate. The mixture was extracted with dichloromethane, and the organic phase was dried over MgSO4 and concentrated under reduced pressure. Purification of the residue on silica gel gave 2-(bromomethyl)-3-(2-chlorophenyl)-2-(2,4-difluorophenyl)oxirane as a 59/41 mixture of diastereoisomers [316 mg, colourless oil, yield 40%; GC/MS: m/z=279 ([M-Br]+); HPLC/MS: log P(HCOOH)=4.61 (major diastereoisomer), 5.00 (minor diastereoisomer)].

Provenance & Evidence