Regioselective synthesis of fluorinated pyrazole derivatives from trifluoromethyl-1,3-diketone
作者:Li-ping Song、Shi-zheng Zhu
DOI:10.1016/s0022-1139(01)00454-7
日期:2001.10
1,1,1-Trifluoropentane-2,4-dione (1a) and 1-(thien-2-yl)-4,4,4-trifluorobutane-1,3-dione (1b) reacted readily with per(poly)fluorophenylhydrazines ArfNHNH2 (Arf: C6F5, HC6F4, ClC6F4) to give N-per(poly)fluorophenyl-5-methyl(or thien-2-yl)-3-trifluoromethylpyrazoles 3 and 3-methyl (or thien-2-yl)-5-hydroxy-5-trifluoromethyl-4,5-dihydropyrazoles 4, respectively. Treatment of 4 with P2O5 yielded the dehydrated
1,1,1-三氟戊烷-2,4-二酮(1a)和1-(噻吩-2-基)-4,4,4-三氟丁烷-1,3-二酮(1b)与per(poly)容易反应氟苯基肼Ar f NHNH 2(Ar f:C 6 F 5,HC 6 F 4,ClC 6 F 4)得到N-全(多)氟苯基-5-甲基(或噻吩-2-基)-3-三氟甲基吡唑3和3-甲基(或噻吩-2-基)-5-羟基-5-三氟甲基-4,5-二氢吡唑4。用P 2 O 5处理4得到高收率的脱水产物N-全(聚)氟苯基-3-甲基(或噻吩-2-基)-5-三氟甲基-吡唑。