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由于碳氟键有很高的稳定性,氟原子有很强的电负性等几何体(isogeometric)效应和优良的脂溶增强效应,因此含氟生物活性物质的合成研究日益引起人们的兴趣和重视.本文报道含强吸电子基的低氟芳烃与可能产生分子内环化的数种亲核试剂的反应,合成低氟芳杂环化合物. 3,5-二硝基-2-氯三氟甲苯(1)中的氯原子受到相邻两个强吸电子基CF_3和NO_2的影响,非常活泼,与巯基乙酸甲酯在三乙胺或吡啶氟化氢溶液催化下,生成2-甲氧羰基-5-硝基-7-三氟甲基苯并噻唑N-氧化物(2),但与呋喃甲硫醇在同样条件下反应,仅得到2,4-二硝基-5-三氟甲苯基呋喃甲硫醚(3a),说明3中—SCH_2—上的氢原子缺乏足够的酸性,不能发生分子内的脱水环化,有趣的是若提高呋喃甲硫醇的摩尔比,则不仅1中2-位的氯被取代,而且5-位的硝基也被取代,生成化合物4;若将1与苯硫酚和苄硫醇反应,则分别得到3b和3c,3b进一步氧化,生成亚砜5.
Due to the high stability of fluorocarbon bonds and the strong electronegative effect of fluorine atoms on the fluorine atoms and the excellent fat-soluble enhancement effect, the synthesis of fluorine-containing bioactive substances has drawn increasing interest and attention In this paper, we report the synthesis of low - fluorine aromatic heterocyclic compounds by reaction of a low fluorine - containing aromatic hydrocarbon with strong electron - withdrawing groups and several nucleophiles which may generate intramolecular cyclization.3,5 - dinitro - 2 - chlorobenzotrifluoride (1) is affected by two adjacent strong electron-withdrawing groups, CF_3 and NO_2, and is very active. With methyl thioglycolate catalyzed by triethylamine or pyridine hydrogen fluoride, 2-methoxycarbonyl-5- Nitro-7-trifluoromethylbenzothiazole N-oxide (2), but with furanmethanethiol under the same conditions to give only 2,4-dinitro-5-trifluoromethylphenyl furfuryl Thioether (3a), indicating that the 3 - CH 2 - hydrogen atoms on the lack of sufficient acidity, intramolecular cyclodehydration can not occur, it is interesting to increase furan methyl mercaptan molar ratio, not only 1 2 - position Of the chlorine is substituted and the nitro group at the 5-position is also substituted to give the compound 4; if 1 is reacted with thiophenol and benzyl mercaptan, 3b and 3c, 3 b Further oxidation to sulfoxide 5.