Lithium triflate (LiOTf): a highly efficient and reusable catalytic system for the synthesis of diversified quinolines under neat conditions

A series of diverse polyfunctionalized quinolines were easily prepared in excellent yields via a Friedlander reaction of o-aminoaryl ketone or o-aminoaryl aldehyde with alpha-methylene ketones using lithium triflate as an expeditious catalyst under solvent free conditions. The protocol provides a practical and straightforward approach toward highly functionalized quinoline derivatives in excellent yields. The catalyst is easily recoverable and less sensitive to moisture, which makes this protocol more advantageous.