Superbase‐Mediated Indirect Friedländer Reaction: A Transition Metal‐Free Oxidative Annulation toward Functionalized Quinolines

A superbase mediated indirect Friedländer reaction towards functionalized quinolines has been realized. The reaction was performed with o‐aminobenzyl alcohol and ketones having an active methylene moiety in the presence of KOH and in DMSO. The reaction proceeds predominantly via initial formation of an imine intermediate and subsequent oxidation of the benzyl alcohol functionality and condensation to afford substituted quinolines. We could also demonstrate that a minor fraction of the reaction proceeds via a chalcone intermediate. The transition metal‐free oxidative annulation was found to be general affording 2‐substituted, 2,3‐disubstituted/fused or multi‐substituted quinolines. The reaction was extended towards the functionalization of natural products and the applicability of the reaction for gram‐scale synthesis of quinolines was also demonstrated. A transition metal‐free superbase mediated indirect Friedländer reaction was developed for accessing functionalized quinolines using o‐aminobenzyl alcohol and ketones with an active methylene moiety. The reaction was employed in the functionalization of natural products and the applicability of the reaction for gram‐scale synthesis of quinolines was also demonstrated.