反应详情

Preparation of ##STR16## a) 8.95 g of 5-chloro-2-methyl-4-(o-tolyl)-2,4-dihydro[1,2,4]triazol-3-one (prepared according to WO 95/14009) and 7.83 g of N-bromosuccinimide are placed in 50 ml of carbon tetrachloride, and a catalytic amount of dibenzoyl peroxide is added. The suspension is then stirred under reflux with illumination (a 500 W photographic lamp) for 11/2 hours. The suspension is concentrated by evaporation and the residue is chromatographed directly on silica gel using hexane/ethyl acetate (6:4). Recrystallization from toluene/heptane (1:1) gives 4-(2-bromomethylphenyl)-5-chloro-2-methyl-2,4-dihydro[1,2,4]triazol-3-one as white crystals of m.p. 131.5-133° C.

1. temperatureunder reflux with illumination (a 500 W photographic lamp) for 11/2 hours
2. concentrationThe suspension is concentrated by evaporation
3. customthe residue is chromatographed directly on silica gel
4. customRecrystallization from toluene/heptane (1:1)