Organic electrosynthesis: electrochemical alkyne functionalization
Methods and techniques that can be used to perform various chemical transformations in an environmentally friendly and safe manner are a current hot topic of interest to the scientific community. Here, we specify one such approach that is able to efficiently synthesize highly functionalised compounds without the need for expensive inorganic catalysts and, in many cases, without harsh reagents and thus, reduce the waste and potential dangers they would otherwise pose. This methodology of electrochemistry has become well established as a synthetic route of significant importance, wherein electricity is provided as the acting oxidising/reducing agent, and even under mild conditions, highly reactive species can be generated in a controlled fashion. In addition, more and more modern day energy is being produced through renewable sources and therefore, electrochemical applications are becoming increasingly more sustainable and economically attractive. Although rare within biological systems, the functionalization of alkynes involves many key chemical transformations including, but not limited to, annulations, hetero-cyclisation reactions, polycyclic aromatic hydrocarbon formation, alkyne–azide cycloaddition in click chemistry, indole derivative synthesis, etc. In recent years, much attention has focused on exploiting carbon–carbon double and triple bonds in chemical transformations using electrolysis. Herein, we outline examples of electrochemical alkyne functionalization reactions in connection with green and sustainable chemistry that proceed with excellent atom economy.