Nitroxide-Mediated Polymerization of Methacrylic Esters: Insights and Solutions to a Long-Standing Problem

Nitroxide-mediated polymerization (NMP) is one of the most powerful reversible deactivation radical polymerization techniques and has incredibly gained in maturity and robustness over the last decades. However, control of methacrylic esters is one of the different aspects of NMP that still requires improvement. This family of monomers always represented an important challenge for NMP, despite the many different nitroxide structures that have been designed over the course of time. This Review aims to present the most successful strategies directed toward the control of the NMP technique of methacrylic esters and especially methyl methacrylate. NMP-derived materials comprising uncontrolled methacrylate segments will also be discussed.

Use of Fluorinated Organic Compounds in Living Radical Polymerizations

Controlled/living radical polymerization (LRP) is a field of special interest because it allows tailoring well-defined macromolecular architectures such as telechelic, block, graft or star copolymers. Since the eighties, several techniques have been reported [such as the iniferter method, nitroxide-mediated radical polymerization (NMP), atom transfer radical polymerization (ATRP), iodine transfer polymerization (ITP), and reversible addition-fragmentation chain transfer (RAFT)] giving rise to a huge number of publications and patents. This review aims at illustrating the contribution of fluorinated organic compounds in this area of research through the use of fluorinated initiators (dithiocarbamates, xanthates, tetraphenylethanes, alkoxyamines, fluorinated alkyl halides, and dithioesters) or other fluorinated molecules (ligands, solvents). Another point depicts the LRP of various fluorinated monomers (methacrylates, acrylates, styrenics, and alkenes). Finally, fluorinated block and graft copolymers prepared by LRP have been reported. A review with 165 references.

The persistent radical effect in organic synthesis

The persistent radical effect (PRE) is a principle that explains the highly selective cross-coupling between a persistent and a transient radical when both species are formed at equal rates. In this paper, the concept of the PRE is briefly discussed. Applications of the PRE in different reactions such as Co-mediated radical addition and cyclization reactions, Kharasch reactions catalyzed by transition metals, the Barton reaction, and our nitroxide-mediated tin-free radical cyclizations are presented. Some future perspectives for the PRE in organic synthesis are also provided.