Oxidant and transition-metal-free photo-induced direct oxidative annulation of 1-aryl-2-(furan/thiophe-2-yl)butane-1,3-diones

【作者】 张瑾； 张曦； 王涛； 姚新波； 王平； 荆思思； 梁勇； 张尊听；

【Author】 Jin Zhang;Xi Zhang;Tao Wang;Xinbo Yao;Ping Wang;Sisi Jing;Yong Liang;Zunting Zhang;School of Chemistry and Chemical Engineering, Shaanxi Normal University;

【机构】 School of Chemistry and Chemical Engineering, Shaanxi Normal University；

【摘要】 A few photo-induced dehydrogenative reaction have been reported, most of them need for oxidant or transition metal. Our group has been focused on the synthesis of various heteroaromatics via the photochemical reactions. Herein, we would like to report the photocyclization of 1-aryl-2-(furan/thiophe-2-yl)butane-1,3-diones and ethyl-3-aryl-2-(furan-2-yl)-3-oxo-propanoates, which underwent an keto-enol tautomerism, affording various highly functionalized heteroaromatics by the elimination of a hydrogen molecule from intermediate A. The functionalized and polyheterocyclic compounds were synthesized via the direct oxidative annulation(UV irradiation) of 1-aryl-2-(furan/thiophe-2-yl)butane-1,3-diones and ethyl-3-aryl-2-(furan-2-yl)-3-oxo-propanoates in the EtOH solution. Notable feature of our strategy include a) mild reaction conditions, b) easy work-up, and c) NO requirement of any catalysts and oxidants. Meanwhile, the fluorescence properties of compounds were determined. The phenomenon of excited-state intramolecular proton transfer(ESIPT) was observed for both 1-(5-hydroxynaphtho[2,1-b]furan-4-yl)ethanone and 1-(5-hydroxyfuran/thieno/pyrrolo[3,2-e]benzofuran-4-yl) ethanone analogues. Meanwhile, ethyl-5-hydroxynaphtho [2,1-b]furan-4-carboxylate observed with a significant enhancement of the fluorescence quantum efficiencies in the EtOH solution.更多还原

【Abstract】 A few photo-induced dehydrogenative reaction have been reported, most of them need for oxidant or transition metal. Our group has been focused on the synthesis of various heteroaromatics via the photochemical reactions. Herein, we would like to report the photocyclization of 1-aryl-2-(furan/thiophe-2-yl)butane-1,3-diones and ethyl-3-aryl-2-(furan-2-yl)-3-oxo-propanoates, which underwent an keto-enol tautomerism, affording various highly functionalized heteroaromatics by the elimination of a hydrogen molecule from intermediate A. The functionalized and polyheterocyclic compounds were synthesized via the direct oxidative annulation(UV irradiation) of 1-aryl-2-(furan/thiophe-2-yl)butane-1,3-diones and ethyl-3-aryl-2-(furan-2-yl)-3-oxo-propanoates in the EtOH solution. Notable feature of our strategy include a) mild reaction conditions, b) easy work-up, and c) NO requirement of any catalysts and oxidants. Meanwhile, the fluorescence properties of compounds were determined. The phenomenon of excited-state intramolecular proton transfer(ESIPT) was observed for both 1-(5-hydroxynaphtho[2,1-b]furan-4-yl)ethanone and 1-(5-hydroxyfuran/thieno/pyrrolo[3,2-e]benzofuran-4-yl) ethanone analogues. Meanwhile, ethyl-5-hydroxynaphtho [2,1-b]furan-4-carboxylate observed with a significant enhancement of the fluorescence quantum efficiencies in the EtOH solution.更多还原