nucleophiles and electron-transferring agents indicated two plausible reactionmechanisms for the dehalogenohydrogenation in acid media: a reaction route via positive halogen transfer resulting from nucleophilic attack on the halogen substituent (SNX process) and that via electron-transfer and unimolecular elimination of halide ion (SRN1 process). The ammonio group and perfluoro substituents on the aromatic
研究了在对位具有碱性氮取代基的全氟苯基卤化物与卤化氢水溶液的反应中,用氢置换了卤素取代基。对卤代N,N-二甲基全氟苯胺与各种卤化氢的反应行为以及对卤代全氟苯基三甲基铵三氟甲磺酸盐与亲核试剂和电子转移剂的反应行为表明,在酸性介质中脱卤加氢有两种可能的反应机理:通过正卤素的反应路线亲核进攻卤素取代基(S N X过程),以及电子转移和单分子消除卤离子(S RN)1个过程)。发现芳族环上的铵基和全氟取代对于进行这种脱卤代氢是必不可少的。
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。