Sc(OTf)3-catalyzed or t-BuOK promoted tandem reaction of 2-(2-(alkynyl)benzylidene)malonate with indole

Tandem reaction of 2-(2-(alkynyl)benzylidene)malonate with indole was investigated. (Z)-1-Benzylidene-3-(1H-indol-1-yl)-1H-indene-2,2(3H)-dicarboxylate was generated in the presence of t-BuOK at room temperature; whereas 3-((1H-indol-3-yl)(2-(alkynyl)aryl)methyl)-1H-indole was obtained when Sc(OTf)(3) was utilized as catalyst at 50 degrees C.