Palladium-catalyzed indolization of N-aroylbenzotriazoles with disubstituted alkynes.

The palladium-catalyzed denitrogenative indolization of N-aroylbenzotriazoles 1 and internal alkynes 2 produced the corresponding polysubstituted indoles 3 in good to high yields. For example, the reaction of 5,6-dimethyl-1-[4-(trifluoromethyl)benzoyl]benzotriazole (1j) with 6-dodecyne (2a), 4-octyne (2b), and diphenylacetylene (2f) in the presence of 10 mol % of Pd(PPh(3))(4) without solvent at 130 degrees C gave the corresponding indoles 3i, 3l, and 3p in 74, 71, and 41% yields, respectively. In the present reaction, the aroylbenzotriazole acts as a synthetic equivalent of a 2-haloanilide in Larock's indole synthesis.