Regiospecific C-H bond activation of aromatic hydrocarbons by gold(III) species and its application for cataytic reactions1

发现无水氯化金（III）对芳烃的C-H键活化在正己烷中不均匀进行，在乙醚中均匀进行，得到芳基金（III）配合物。由于上述反应所得到的配合物[{AuCl_2Ar}_2]在固态下也是相当不稳定的，而且逐渐分解，因此分离出了[AuCl_2Ar（2，6-二甲基吡啶）]的单核配合物。研究了硝基苯、苯乙酮、二氯苯、氯苯、苯、甲苯、二甲苯、均三甲苯、异丙苯、苯甲醚和苯甲醚等芳烃与无水氯化金的反应。结果表明，金（III）物种的C-H键活化具有亲电性和区域特异性。X射线衍射分析表明，配合物[AuCl_2Ar（2，6-二甲基吡啶）]具有反式构型，苯环和吡啶环几乎垂直于金的配位面，并研究了[AuCl_2Ar（2，6-二甲基吡啶）]与苯乙烯、二苯乙炔、乙炔二甲酸二甲酯、苯乙炔、丙炔酸甲酯等不饱和化合物的反应。发现烯烃（苯乙烯）以及内炔（二苯乙炔和乙炔二甲酸二甲酯）根本不反应。与此相反，末端炔基苯乙炔生成芳基化炔基二苯乙炔，而末端炔基丙炔酸甲酯生成氯代肉桂酸甲酯衍生物ArCH = CCI（CO_2Me）。此外，这些化合物得到了相当好的产率通过使用芳基金（III）物种原位生成的无水氯化金（III）与相应的芳香族化合物的反应。关于催化反应，我们在短时间内无法进行研究。

It was found that C-H bond activation of aromatic hydrocarbons by anhydrous gold(III) chloride proceeded heterogeneously in hexane and homogeneously in diethyl ether to afford arylgold(III) complexes. As the complexes [{AuCl_2Ar}2] obtained by the above reactions are fairly unstable and gradually decomposed even in the solid state, the arylgold(III) complexes were isolated as mononuclear complexes of [AuCl_2Ar(2,6-lutidine)]. Reactions of anhydrous gold(III) chloride with aromatic hydrocarbons were investigated using nitrobenzene, acetophenone, dichlorobenzenes, chlorobenzene, benzene, toluene, xylenes, mesitylene, cumene, anisole and. As the results, it was revealed that C-H bond activation by gold(III) species proceeds electrophilically and regiospecifically. The X-ray structural analysis showed that complex [AuCl_2Ar(2,6-lutidine)] has trans configuration and both the benzene and pyridine rings stand nearly perpendicular to the co-ordination plane of gold.The reactions of arylgold(III) complexes of [AuCl_2Ar(2,6-lutidine)] with unsaturated compounds such as styrene, diphenylacetylene, dimethyl acetylenedicarboxylate, phenylacetylene, methyl propiolate and so on were investigated. It was found that alkene (styrene) as well as inner alkynes (diphenylacetylene and dimethyl acetylenedicarboxylate) did not react at all. On the contrary, a terminal alkyne phenylacetylene produced an arylated alkyne diphenylacetylene, whereas a terminal alkyne methyl propiolate yielded chlorinated methyl cinnamate derivatives ArCH = CCI(CO_2Me). Moreover, these compounds were obtained in fairly good yields by using arylgold(III) species generated in situ by the reactions of anhydrous gold(III) chloride with corresponding aromatic compounds. Concerning catalytic reactions, we could not investigate for the short period of research time.