Metal-Free Ring-Opening Metathesis Polymerization: From Concept to Creation.

Ring-opening metathesis polymerization (ROMP), which is derived from transition-metal-based olefin metathesis, has evolved into one of the most prevalent technologies for making functional polymeric materials in academia and in industry. The initial discovery of and advances in ROMP used ill-defined mixtures of metal salts to initiate polymerization. The initiators most commonly used today, developed with tremendous efforts, are well-defined metal-alkylidene complexes that have enabled a good mechanistic understanding of the polymerization as well as improvement of the initiators' activity, stability, and functional group tolerance.

Molecular Weight Control via Cross Metathesis in Photo-Redox Mediated Ring-Opening Metathesis Polymerization.

Photo-redox mediated ring-opening metathesis polymerization (photo-ROMP) is an emerging ROMP technique that uses an organic redox mediator and a vinyl ether initiator, in contrast to metal-based initiators traditionally used in ROMP. The reversibility of the redox-mediated initiation and propagation steps enable spatiotemporal control over the polymerization. Herein, we explore a simple, inexpensive means of controlling molecular weight, using alpha olefins as chain transfer agents.

Preparation of 6-aminocyclohepta-2,4-dien-1-one Derivatives via Tricarbonyl(tropone)iron.

aza-Michael adducts of tricarbonyl(tropone)iron are synthesized by two different methods. Primary aliphatic amines and cyclic secondary amines participate in a direct aza-Michael reaction with tricarbonyl(tropone)iron under solvent-free conditions. Less nucleophilic aniline derivatives and more hindered secondary amines add efficiently to the cationic tropone complex formed by protonation of tricarbonyl(tropone)iron.