A greener, facile and scalable synthesis of indole derivatives in water: reactions of indole-2,3-diones with 1,2-difunctionalized benzene

An efficient, facile and greener protocol for the synthesis of indole derivatives viz., 3′H-spiro[indole-3,2′-[1,3]benzothiazole]-2(1H)-ones, 6H-indolo[2,3-b]quinoxalines and 3-(2-hydroxy-phenylimino)-1,3-dihydro-indol-2-ones, by the reactions of indole-2,3-diones with 1,2-difunctionalized benzene using tetrabutylammonium bromide (TBAB), as a surfactant under aqueous micellar media is described. This methodology has advantages of simple handling, mild reaction conditions and high yields of products in shorter reaction time as well as environmentally benign synthesis.