One-Pot Synthesis of 2,4-Disubstituted Indoles from N-Tosyl-2,3-dichloroaniline Using Palladium-Dihydroxyterphenylphosphine Catalyst

4-Chloroindoles were synthesized from readily available 2,3-dichloroaniline derivatives and terminal alkynes. The catalyst composed of palladium and dicyclohexyl(dihydroxyterphenyl)phosphine (Cy-DHTP) enabled ortho-selective Sonogashira coupling, and subsequent cyclization afforded 4-chloroindoles in high yields. This transformation was successfully applied to the one-pot synthesis of 2,4-disubstituted indoles via Suzuki-Miyaura coupling after indole formation.