Oxidant and Transition-Metal-Free Photoinduced Direct Oxidative Annulation of 1-Aryl-2-(furan/thiophen-2-yl)butane-1,3-diones

A photoinduced direct oxidative annulation of 1-ary1-2(furan/thiophen-2-yObutane-1,3-diones and ethy1-2-(furan-2-y1)-3-oxo-3(ary1-2-yl)propanoates in EtOH without the need for any transition metals and oxidants provided access to highly functionalized polyheterocyclic 1(5-hydroxynaphtho [2,1-b.] furan-4-y1) ethano ne s and 1- (5-hydroxyfuran/thieno/pyrrolo [3,2-e]benzofuran-4-yl)ethanones. The phenomenon of excited-state intramolecular proton transfer (ESIPT) was observed for both 1-(S-hydroxynaphtho[2,1-b]furan-4-yl)ethanone and 1-(5-hydroxy furan/thieno/pyrrolo [3,2-db enzofuran-4-y1) ethanone analogues.