Formation of tetrasubstituted C-C double bonds via olefin metathesis: challenges, catalysts, and applications in natural product synthesis

Among the many types of transition-metal-catalysed C-C bond forming reactions, olefin metathesis is without a doubt one of the most thriving fields in modern organic synthetic chemistry. This is due to a wide range of transformations that are possible by olefin metathesis with commercially available and user friendly catalysts. Until recently, the formation of tetrasubstituted double bonds via olefin metathesis is considered as a very challenging topic. Although much attention has already been given in the last two decades to improve this transformation by the modification of catalysts, optimising the conditions, substrate modification and so on, however, none are universally attractive so far. So the field is still quite open and looking for a simple and general solution that suits all challenging substrates. In this context, this review is an attempt to provide a broad but digestible overview of tetrasubstituted C-C double bond formation via olefin metathesis, with an emphasis on the recent developments achieved in this area. These developments are actually signifying the great potential for further advancement of this exhilarating research field.