Editorial: The Catalysis of Ring Synthesis

Abstract

Ring systems -aromatic or non-aromatic carbocyclic and heterocyclic structures -represent key scaffolds in biologically important molecules. In particular, heterocycles are fundamental building blocks of most small-molecule drugs on the market today. Furthermore, aromatic and heteroaromatic ring systems are of eminent importance for material sciences and are playing a significant role as chromophores, liquid crystalline materials, molecular receptors, redox materials, organic light-emitting diodes, and photochemical switches, etc.Catalysis, including transition-metal catalysis, organocatalysis, nanocatalysis, photoredox catalysis, has become as a powerful tool for the synthesis of different ring systems. This Special Collection "The Catalysis of Ring Synthesis" covers the most recent strategies of ring synthesis and presents the current advances in the field.A Review by Kotha and co-authors summarizes new synthetic methods to diverse cage polycycles potentially useful for high energy density materials synthesis. [1] In the Review paper by Neto and Zeni the diverse variety of synthesis of pyrrole derivatives using the reaction of alkynes with nitrogencompounds under transition metal-catalyzed and metal-free conditions, is presented. [2] A Minireview from the group of Das reflects the impressive state of the art in photoredox catalysis and the recent applications of photocatalysis to [2 + 2] and [4 + 2] cycloaddition reactions under the irradiation of visible light. [3] Efficient organocatalyzed and/or transition-metal-catalyzed synthesis of azirine, pyridine, piperidine, indole, indoxyl, benzimidazole, carbazole, spiro pyrrolidone, γ-(thio)butyrolactone, quinolone derivatives and oligocyclic systems are reported in a total of 12 Communications. A highly efficient enantioselective organocatalytic synthesis of trisubstituted [a]