Metal-Free Oxidative C-C Bond Formation through C-H Bond Functionalization

The formation of C-C bonds embodies the core of organic chemistry because of its fundamental application in generation of molecular diversity and complexity. C-C bond-forming reactions are well-known challenges. To achieve this goal through direct functionalization of C-H bonds in both of the coupling partners represents the state-of-the-art in organic synthesis. Oxidative C-C bond formation obviates the need for prefunctionalization of both substrates. This Minireview is dedicated to the field of C-C bond-forming reactions through direct C-H bond functionalization under completely metal-free oxidative conditions. Selected important developments in this area have been summarized with representative examples and discussions on their reaction mechanisms.

Rhodium-catalyzed oxidative decarbonylative Heck-type coupling of aromatic aldehydes with terminal alkenes

A rhodium-catalyzed oxidative decarbonylative Heck-type coupling of aromatic aldehydes and terminal alkenes to afford 1,2-disubstituted alkenes with good regio- and E-selectivity is developed.

To be or not to be metal-free: trends and advances in coupling chemistries

Coupling reactions have been part of several extensive studies in order to develop innovative and greener protocols that can generate a wide range of compounds with applications in pharmaceuticals, agrochemicals and biologically active compounds. Metal-free couplings are an important and increasingly trendy field that has attracted a significant deal of interest in recent years, generating a lot of controversy on the issue of whether metal free is really free. Aside from focusing on such a controversial topic itself, this contribution aims to provide a brief introduction on coupling chemistry to point out the transition of this technology from metal-catalyzed to metal-free. This is followed by a range of key selected synthetically useful metal-free processes and a brief commentary on the current debate of whether metal-free reactions are really metal-free and the required experiments for a full understanding of a metal-free coupling process.