Cascade annulations of aryldiazonium salts, nitriles and halo-alkynes leading to 3-haloquinolines

Abstract A regiospecific access to 3-haloquinolines has been developed via a three-component annulation of aryldiazonium salts, nitriles and haloalkynes. This reaction proceeds through an initial formation of reactive nitrilium ion and further cascade annulation with haloalkynes. This method provides a straightforward access to a diverse array of functionalized quinolones (28 examples) under mild conditions and exhibits broad functional group tolerance. Applications of this method in a gram scale reaction and a formal synthesis of Pitavastatin are illustrated.