The synthesis of cyclic polymers by olefin metathesis: Achievements and challenges

Abstract

This manuscript is dedicated to Professor Mitsuo Sawamoto's outstanding achievements in polymer chemistry and recognizes his recent retirement from 40 years of exceptional service to Kyoto University.ABSTRACT: Cyclic polymers have drawn considerable interest for their peculiar physical properties in comparison to linear polymers, despite their equivalent compositions. Synthetically, cyclic polymers can be accessed through either macrocyclic ringclosure or by ring-expansion polymerization, but the main challenge with either method is the production of highly pure cyclic polymer samples. This highlight describes advances in the area of cyclic polymer synthesis, with a particular focus on ring-expansion metathesis polymerization. Methods for characterizing cyclic polymers and assessing their purity are also discussed in order to emphasize the need for additional robust and reliable methods for synthesizing and studying topologically complex macromolecules.

Toward E-selective Olefin Metathesis: Computational Design and Experimental Realization of Ruthenium Thio-Indolate Catalysts

“…Olefin metathesis offers an atomefficient catalytic alternative, in which olefinic fragments are rearranged by scission and regeneration of carbon-carbon double bonds [8][9][10]. Thanks to the ease of handling and functional-group tolerance of ruthenium catalysts [11][12][13], olefin metathesis has been widely adopted for the synthesis of complex organic molecules [14][15][16][17], including pharmaceuticals [18][19][20][21], and soft materials [22][23][24][25][26][27][28][29][30][31].…”

Synthesis of Cyclic Polyolefin: Ring‐Opening Metathesis Polymerization by Binuclear Vanadium Complexes†

“…The following ring‐expansion metathesis polymerization (REMP) will release the cyclic polymer and regenerate the cyclic catalyst. [ 18‐20 ] Especially in the step of release polymer by backbiting, the internal carbon double bond has similar possibility to react with either metal alkylidenes, which will lead to different polymer sizes.…”

Well-defined cyclic polymer synthesis via an efficient etherification-based bimolecular ring-closure strategy

“…1,3 In general, there are two major strategies to synthesize cyclic polymers: (a) ring-expansion, where the cyclic topology of the growing polymer chain is preserved throughout, and (b) ring-closure of a linear polymer. 4,5 The ring-expansion approach is induced by the insertion of monomer units into an activated ( pseudo) cyclic chain. 6,7 This method avoids high dilution and precursors with functionalized end groups; however, it has limitations towards different monomers.…”