作者:Rajdip Karmakar、Sourav Ghorai、Yuanzhi Xia、Daesung Lee
DOI:10.3390/molecules200915862
日期:——
Trapping of arynes with various nucleophiles provides a range of heteroatom-functionalized arene derivatives, but the corresponding reaction with water does not provide phenol derivatives. Silver trifluroacetate (AgO2CCF3) can nicely solve this problem. It was found that in typical organic solvent, AgO2CCF3 readily reacts with arynes to generate trifluoroacetoxy organosilver arene intermediate, which, upon treating with silica gel, provides phenolic products. This protocol can be extended to the synthesis of α-halofunctionalized phenol derivatives by simply adding NBS (N-bromosuccinimides) or NIS (N-iodosuccinimides) to the reaction along with silver trifluroacetate, which provided α-bromo or α-iodophenol derivatives in good yield. However, the similar reactions with NCS (N-chlorosuccinimides) afforded only the protonated product instead of the expected α-chlorophenols derivatives. Interestingly, substrates containing silyl substituents on 1,3-diynes resulted in α-halotrifluoroacetates rather than their hydrolyzed product. Additionally, trapping the same arynes with other oxygen-based nucleophiles containing silver counter cation, along with NXS (N-halosuccinimides), generated α-halooxyfunctionalized products.
芳炔与各种亲核物的捕获反应可提供一系列杂原子官能化的炔衍生物,但与水的相应反应却不能提供苯酚衍生物。三氟乙酸银(AgO2CCF3)可以很好地解决这个问题。研究发现,在典型的有机溶剂中,AgO2CCF3 很容易与芳香烃反应生成三氟乙酰氧基有机银炔中间体,用硅胶处理后可得到酚类产物。只需在反应中加入 NBS(N-溴代琥珀酰亚胺)或 NIS(N-碘代琥珀酰亚胺)以及三氟乙酸银,即可将此方案扩展到 α-半官能化苯酚衍生物的合成,从而以良好的收率获得 α-溴或 α-碘苯酚衍生物。然而,与 NCS(N-氯代丁二酰亚胺)的类似反应只能得到质子化产物,而不是预期的 α-氯苯酚衍生物。有趣的是,1,3-二炔上含有硅基取代基的底物会产生 α-卤代三氟乙酸酯,而不是其水解产物。此外,用其他含银反阳离子的氧基亲核物和 NXS(N-卤代丁二酰亚胺)捕获相同的芳烃,也会产生 α-卤氧基官能化产物。