抄録
While multi-component reaction (MCR) is a powerful approach to the development of efficient and practical synthetic methods that minimize the reagents, solvents, cost, time, and formation of waste, a catalytic tandem reaction including MCR would be more attractive to achieve this goal. We investigated tandem three-component coupling-indole formation using some ethynylanilines, secondary amines, and paraformaldehyde under various conditions. We found that this tandem reaction requires only 1 mol % of CuBr and 1.1 equivalents of amine components to give the desired 2-(aminomethyl)indoles in high yields. Furthermore, in combination with the palladium-catalyzed C-H activation, this MCR-indole formation is also applicable to the two-step synthesis of polycyclic indoles such as dihydrobenzoazepine-fused indole and tetrahydropyridine-fused indole in high chemical yields.
