Compounds featuring weakly-coordinating N-oxides or carbonyl groups, as for instance, quinoline N-oxide and quinonoid systems represent important structural scaffolds with potential biological activities. Due to their biological importance, significant efforts have been devoted to devise robust methods for their step-economical preparation. Among these approaches, the C–H activation strategy has emerged as a powerful, versatile and efficient tool in molecular sciences. This feature article summarizes recent key advances in transition-metal-catalyzed C–H functionalization for A-ring functionalization of heterocyclic and quinoidal compounds by challenging weakly-coordinating entities, published prior to May 2018.