Novel and Convenient Synthesis of Substituted Quinolines by Copper- or Palladium-Catalyzed Cyclodehydration of 1-(2-Aminoaryl)-2-yn-1-ols

Abstract

A general and convenient synthesis of substituted quinolines by regioselective copper- or palladium-catalyzed 6-endo-dig cyclization-dehydration of 1-(2-aminoaryl)-2-yn-1-ols is reported. The crude substrates were easily obtained by the Grignard reaction between the appropriate alkynylmagnesium bromide and 2-aminoaryl ketones and could be used without further purification for the subsequent cyclization step. Heteroannulation reactions were carried out in MeOH or DME as the solvent at 60 or 100 degrees C in the presence of CuCl(2) or PdX(2) (in conjunction with 10 equiv of KX, X = Cl, I) as the catalyst to afford the quinoline derivatives in good to excellent isolated yields based on starting 1-(2-aminoaryl)-2-yn-1-ols (66-90%).