A quick and efficient route to substituted quinolines by electrophilic cyclization of 1-(2-aminoaryl)-2-yn-1-ols

Abstract

A practical method for the synthesis of substituted quinolines from 2-aminoarylketones (via 1-(2-aminoaryl)-2-yn-1-ols) using mild and simple reaction conditions is described. A study of several electrophiles in various reaction conditions is presented. Out of three electrophilic iodine sources (I2, NIS and ICl) studied, I2 was found to work efficiently for the synthesis of 3-iodoquinolines. Several Brønsted acids (pTSA, PPTS, AcOH, TFA, HCl) were able to catalyze the formation of 2,4-substituted quinolines from the same starting materials. Good to excellent overall yields were observed with both aromatic and aliphatic substitutions at the reaction center.