1-(2-氯苯基)-2-(4-氟苯基)-3-溴-1-丙烯的合成

Synthesis of 1-(2-Chlorophenyl)-2-(4-fluorophenyl)-3-bromopropene

1-(2-氯苯基)-2-(4-氟苯基)-3-溴-1-丙烯(2)是氟环唑的关键中间体。以1,2-二氯乙烷和水为溶剂,1-(2-氯苯基)-2-(4-氟苯基)-1-丙烯(1)在氢溴酸/双氧水体系中发生α-溴代反应得到该化合物。通过使用氢溴酸/双氧水代替溴素或N-溴代丁二酰亚胺,提高了溴的利用率及产品的收率,避免了烯烃的加成,减少了副反应的发生,减少了三废。通过实验获得了反应的优惠条件:二氯乙烷和水为溶剂,回流反应,n(1)∶n(HBr)∶n(H2O2)=1∶1.1∶2.5,氢溴酸和双氧水的滴加时间为6 h,在上述反应条件下,反应收率为90.6%,选择性90.6%。

1-(2-Chlorophenyl)-2-(4-fluorophenyl)-3-bromopropene(2),an important intermediate of Epoxiconazole,was prepared by the reaction of 1-(2-chlorophenyl)-2-(4-fluorophenyl)-propene with HBr/H2O2 at reflux temperature using the mixture of water and 1,2-dichloroethane as the solvent.Compared with the system of using Br2 or NBS as the bromine resources,the former showed higher yield and less by-products from side reaction of addition of the olefin,therefore less wastes were formed.Under optimal reaction conditions the target product was obtained in 90.6% yield with a selectivity of 90.6%.