Synthetic Strategy for Mechanically Interlocked Cyclic Polymers via the Ring-Expansion Polymerization of Macrocycles with a Bis(hindered amino)disulfide Linker

2021 ◽  
Author(s):  
Rikito Takashima ◽  
Daisuke Aoki ◽  
Hideyuki Otsuka
Keyword(s):  
Ring Expansion ◽  
Cyclic Polymers ◽  
Synthetic Strategy

Synthesis of Cyclic Polymers:  Ring-Expansion Reaction of CyclicS-Dithioester with Thiiranes

2005 ◽  
Vol 38 (14) ◽  
pp. 5964-5969 ◽  
Author(s):  
Hiroto Kudo ◽  
Shinya Makino ◽  
Atsushi Kameyama ◽  
Tadatomi Nishikubo
Keyword(s):  
Ring Expansion ◽  
Cyclic Polymers ◽  
Ring Expansion Reaction

scholarly journals Synthesis of Highly Functionalised Furo[3,4-b]pyrans: Towards the Fungal Metabolite (−)-TAN-2483B

2021 ◽  
Author(s):  
◽  
R.M. Kalpani K. Somarathne
Keyword(s):  
Natural Products ◽  
Total Synthesis ◽  
Natural Product ◽  
Cyclopropane Ring ◽  
Ring Expansion ◽  
Ethyl Esters ◽  
Pyran Ring ◽  
Synthetic Strategy ◽  
Alternative Approach ◽  
Synthetic Approaches

<p>Carbohydrate-derived cyclopropanes combine both the stereochemical wealth of carbohydrates and the reactivity of cyclopropanes. A diverse variety of reaction modes for these cyclopropyl carbohydrates can be harnessed for the synthesis of natural products and other targets.  The natural products (−)-TAN-2483A and (−)-TAN-2483B are fungal secondary metabolites displaying a variety of bioactivities such as inhibition of c-src kinase action and parathyroid hormone-induced bone resorption. This thesis described several synthetic approaches to the natural product (−)-TAN-2483B and analogues of (−)-TAN-2483B employing cyclopropane ring expansion.  The synthetic route to (−)-TAN-2483B began with the readily available substrate D-mannose. The pyran ring unsaturation of the natural product was established by a cyclopropanation-ring expansion sequence. A synthetic strategy via dichlorocyclopropane-based intermediates is described in chapter 2. This being unsuccessful, an alternative approach via 2-fomyl-glycal was developed in chapter 3. The chapter 2 and 3 provided a solid background for the achievement of the analogues synthesis illustrated in chapter 4 via dibromocyclopropane. Lewis acid-mediated alkynylation followed by Pdcatalysed carbonylative lactonisation was successfully utilised in the revelation of the furo[3,4-b]pyran ring skeleton. This route afforded analogues of TAN-2483B; the Z-and E-unsaturated ethyl esters 140 and 141 and hydroxy(−)-TAN-2483B 145. The total synthesis of (−)-TAN-2483B was not achieved due to unforeseen obstacles encountered in the deoxygenation of the side arm of 335 (Chapter 4) into the E-propenyl side arm of (−)-TAN-2483B.</p>

scholarly journals A scalable and continuous access to pure cyclic polymers enabled by quarantined heterogeneous catalysts

2021 ◽  
Author(s):  
Ki-Young Yoon ◽  
Jinkyung Noh ◽  
Quan Gan ◽  
Julian Edwards ◽  
Robert Tuba ◽  
...  
Keyword(s):  
Heterogeneous Catalysts ◽  
Continuous Process ◽  
Ring Expansion ◽  
Ruthenium Catalysts ◽  
Cyclic Polymers ◽  
Cyclic Polymer ◽  
Polymer Separation ◽  
Scalable Synthesis ◽  
Kinetics Of

Cyclic polymers are topologically interesting and envisioned as a lubricant material. However, scalable synthesis of pure cyclic polymers remains elusive. The most straightforward way is to recycle a used catalyst for the synthesis of cyclic polymers. Unfortunately, it is demanding because of the catalyst’s vulnerability and inseparability from polymers, which depreciates the practicality of the process. Here, we develop a continuous process streamlined in a circular way that polymerization, polymer separation, and catalyst recovery happen in situ, to dispense a pure cyclic polymer after bulk ring-expansion metathesis polymerization of cyclopentene. It is enabled by introducing silica-supported ruthenium catalysts and a newly-designed glassware. Also, different depolymerization kinetics of the cyclic polymer from its linear analogue is discussed. This process minimizes manual labor, maximizes security of vulnerable catalysts, and guarantees purity of cyclic polymers, thereby showcasing a prototype of a scalable access to cyclic polymers with increased reusability of precious catalysts (≥415,000 turnovers).

Introducing “Ynene” Metathesis: Ring-Expansion Metathesis Polymerization Leads to Highly Cis and Syndiotactic Cyclic Polymers of Norbornene

2016 ◽  
Vol 138 (20) ◽  
pp. 6408-6411 ◽  
Author(s):  
Soufiane S. Nadif ◽  
Tomohiro Kubo ◽  
Stella A. Gonsales ◽  
Sudarsan VenkatRamani ◽  
Ion Ghiviriga ◽  
...  
Keyword(s):  
Ring Expansion ◽  
Cyclic Polymers ◽  
Metathesis Polymerization

Synthesis of cyclopolyolefins via ruthenium catalyzed ring-expansion metathesis polymerization

2014 ◽  
Vol 86 (11) ◽  
pp. 1685-1693 ◽  
Author(s):  
Robert Tuba
Keyword(s):  
Preliminary Investigation ◽  
Engineering Application ◽  
Physical And Mechanical Properties ◽  
Ring Expansion ◽  
Structure Property ◽  
Cyclic Polymers ◽  
Metathesis Polymerization ◽  
Material Development ◽  
Recent Developments ◽  
Group Density

Abstract Polymers exhibiting cyclic topology have attracted great interest over the past 30 years. Macrocycles or cyclopolymers with more than 20 repeating monomer units are considered exceptional candidates for thermoplastic engineering application due to unique properties in comparison to their linear analogues including large hydrodynamic radii and functional group density, heat resistance, good insulating ability and low intrinsic viscosity. Cyclic polymers are thus expected to exhibit improved physical and mechanical properties for certain applications due to the absence of end groups. Although synthetic challenges have historically limited research on cyclic polymers, recent developments in ruthenium catalyzed ring-expansion metathesis polymerization (REMP) have enabled the synthesis and the preliminary investigation of structure-property relationships of high molecular weight macrocycles. In REMP reactions the polymer formation is proposed to proceed through a transient macrocyclic complex in which both ends of the growing polymer chain remain attached to the Ru center. This article summarizes the recent discoveries on the field of REMP assisted cyclopolymer based material development.

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