Regioselective alkynylation of 2-aryl-4-chloro-3-iodoquinolines and subsequent arylation or amination of the 2-aryl-3-(alkynyl)-4-chloroquinolines

Palladium–CuI catalyzed Sonogashira coupling of 2-aryl-4-chloro-3-iodoquinolines with terminal acetylenes (1 equiv) in triethylamine afforded the 2-aryl-3-(alkynyl)-4-chloroquinolines as sole products. The 2-aryl-4-chloro-3-iodoquinolines coupled with excess terminal acetylenes (2.5 equiv) in dioxane/water to yield the 2-aryl-3,4-bis(alkynyl)quinoline derivatives in a one-pot operation. The 2-aryl-3-(alkynyl)-4-chloroquinolines were, in turn, subjected to arylation via Suzuki cross-coupling with arylboronic acid derivatives or amination with methylamine, respectively. The structures of the products of successive Sonogashira and Suzuki cross-couplings were also confirmed by X-ray crystallography.