Cascade reaction of β,γ-unsaturated α-ketoesters with phenols in trityl chloride/TFA system. Highly selective synthesis of 4-aryl-2H-chromenes and their applications
作者:Yan-Chao Wu、Hui-Jing Li、Li Liu、Zhe Liu、Dong Wang、Yong-Jun Chen
DOI:10.1039/c0ob01143f
日期:——
The treatment of β,γ-unsaturated α-ketoesters with phenols in the presence of trityl chloride and 4 Å molecular sieves in refluxing trifluoroacetic acid afforded 4-aryl-2H-chromenes in high yields, in which a reverse of the regiochemistry of Jørgensen–Rutjes chromane synthesis was observed. The isolation of 4H-chromene intermediates, confirmed by single-crystal X-ray analysis, indicates that the early
存在下苯酚处理β,γ-不饱和α-酮酸酯的研究。 三苯甲基氯 和4Å分子筛回流 三氟乙酸以高收率获得了4-芳基-2 H-色烯,其中Jørgensen–Rutjes的区域化学反应相反苯甲醚观察到合成。通过单晶X射线分析证实了4 H-色烯中间体的分离,表明该反应的早期阶段涉及Friedel-Crafts烷基化/环脱水过程。搅拌4 H-色烯中间体三苯甲基氯 在 氘代三氟乙酸回流下得到2 H-色烯和三苯甲烷以高收率,这意味着反应的后期涉及氢转移过程。进一步实现了羟基酯向相应的羟基酰胺,氨基酸,氨基酯和Friedel-Crafts加合物的高度选择性衍生。我们的努力将使人们更好地理解其结构图案背后的控制要素。从其光谱和通过单晶X射线分析清楚地证实了产物。