One-pot two-step synthesis of 3-iodo-4-aryloxy coumarins and their Pd/C-catalyzed annulation to coumestans
作者:Niranjan Panda、Irshad Mattan
DOI:10.1039/c7ra12419h
日期:——
efficient protocol for the synthesis of various coumestans from the intramolecular annulation of 3-iodo-4-aryloxy coumarins through C–H activation has been developed. When 3-iodo-4-aryloxy coumarins were treated with 10% Pd/C (0.3 mol% Pd) in the presence of sodium acetate, the corresponding coumestans were produced in good to excellent yield. Reusability of the palladium catalyst was investigated in
已经开发了一种通过 C-H 活化从 3-iodo-4-aryloxy 香豆素的分子内环化合成各种香豆素的有效方案。当在乙酸钠存在下用 10% Pd/C (0.3 mol% Pd) 处理 3-iodo-4-aryloxy 香豆素时,相应的香豆素以良好的产率产生。在多达三个连续循环中研究了钯催化剂的可重复使用性,发现反应的产率几乎没有改变。顺序碘化和O4-羟基香豆素的α-芳基化产生3-碘-4-芳氧基香豆素也可以在一锅两步法中以高产率从芳基碘化物开始。发现新戊酸是后一种方法生产 3-碘-4-苯氧基香豆素的最有效添加剂。带有给电子基团和吸电子基团的不同官能团也对反应条件具有耐受性。