An efficient synthesis of 2,2-bis(1H-indol-3-yl)-2H-acenaphthen-1-one catalyzed by recyclable solid superacid SO42−/TiO2 under grinding condition

An efficient synthesis of symmetrical 2,2-bis(1H-indol-3-yl)-2H-acenaphthen-1-one is achieved via a reaction of acenaphthenequinone and indoles catalyzed by solid superacid SO42−/TiO2 under solvent-free conditions at room temperature by grinding, which provides an efficient route to the synthesis of symmetrical 2,2-bis(1H-indol-3-yl)-2H-acenaphthen-1-one. This procedure offers several advantages including solvent-free conditions, excellent yields of products, simple work-up as well as reuse of catalysts which makes it a useful and attractive protocol for the synthesis of these compounds.