Effective Synthesis and Modification of α‐Cyclodextrin‐Based [3]Rotaxanes Enabling Versatile Molecular Design

Akae, Yosuke; Sogawa, Hiromitsu; Takata, Toshikazu

doi:10.1002/ejoc.201900362

Cited by 19 publications

(10 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The said authors used an orthogonal agent containing the acylazide group as the RAFT initiator, and they demonstrated that various vinyl monomers could be polymerized in a living fashion from the initiator. Acylazide species can be easily synthesized starting from carboxylic acids by making the acids react with diphenylphosphoryl azide (DPPA) and then converting the products, thus obtaining reactive isocyanate groups by simple heating. − The thus produced acylazide species can be regarded as potential sources of the reactive moiety of the end-reactive polymer. For example, the hydroxyl group of 4-hydroxymethylbenzoylazide ( 1 ) can be utilized to initiate a living ring-opening polymerization of lactone species in mild reaction conditions, which would afford an end-reactive polyester (Figure ).…”

Section: Introductionmentioning

confidence: 99%

Alcohol Moiety-Tethering Acylazides as Versatile Isocyanate Precursors for Polymerization Initiators and Monomers

2021

Self Cite

View full text Add to dashboard Cite

We have developed alcohol moiety-containing stable acylazides as isocyanate precursors that can be employed as polymerization initiators and monomers. Living ring-opening polymerization of δ-valerolactone was initiated by 4-hydroxymethylbenzoylazide (1) in the presence of diphenyl phosphate as a catalyst under mild conditions to afford a polyester possessing the acylazide-functionalized initiation end. After the protection of the terminal OH group of the polyester, Curtius rearrangement of the acylazide moiety triggered by heating generated an isocyanate-terminated polyester quantitatively. Simple heating of 1 at 110 °C efficiently yielded in situ an alcohol–isocyanate compound acting as an AB-type monomer, which produced the corresponding polyurethane in 79% yield via a Lewis acid-catalyzed polyaddition. A pyridine moiety-containing acylazide also underwent a catalyst-free polyaddition to afford the corresponding polyurethane in 88% yield, performing a similar polyurethane synthesis in the presence of an isocyanate-containing polyester; moreover, it afforded a polyester–polyurethane block copolymer, emphasizing the versatility of alcohol moiety-containing stable acylazides.

show abstract

Section: Introductionmentioning

confidence: 99%

Alcohol Moiety-Tethering Acylazides as Versatile Isocyanate Precursors for Polymerization Initiators and Monomers

2021

Self Cite

View full text Add to dashboard Cite

show abstract

“…Commercially available solvents and reagents were used as received. Pseudo[3]rotaxane 1 and bulky diisocyanate 2 were synthesized as described in the literature . Poly(propylene glycol) bis(2,4-trylene diisocyanate terminated) ( NCO-PPG , M n = 2300) was purchased from Merck Co., Ltd. 1 H NMR spectra were recorded using a Bruker BioSpin AVANCE DPX-300 spectrometer and a Bruker AVANCEIIIHD500 spectrometer utilizing deuterated solvents.…”

Section: Methodsmentioning

confidence: 99%

“…Meanwhile, we developed methods for synthesizing CD-based rotaxanes by end-capping of pseudo[3]rotaxanes containing 1,12-diaminoalkane axles with bulky phenyl isocyanates. − Because [3]rotaxanes were obtained in good yields, this suggests that pseudo[3]rotaxane may be a useful comonomer for polyrotaxane synthesis. If we use an end-reactive polymer as a macromonomer for polymerization with pseudo[3]rotaxane, we can obtain polyrotaxane with a poor CD coverage, which is difficult to synthesize.…”

Section: Introductionmentioning

confidence: 99%

Main Chain-Type Polyrotaxanes Derived from Cyclodextrin-Based Pseudo[3]rotaxane Diamine and Macromolecular Diisocyanate: Synthesis, Modification, and Characterization

et al. 2020

Self Cite

View full text Add to dashboard Cite

We prepared main chain-type polyrotaxanes by urea bond-forming polyaddition of a diamine axle-containing αcyclodextrin (α-CD)-based pseudo[3]rotaxane to a macromolecular diisocyanate derived from poly(propylene glycol). Bulky isocyanate or aniline used as a comonomer worked as an effective stopper during the key step of the polyrotaxane synthesis. In the polymer preparation, the chain extension method worked effectively to increase the polymerization degree. Polyrotaxane was modified by the main chain extension and the cross-linking of hydroxyl groups of the CD wheels. The morphology and the effect of the rotaxane structure on the thermal and physical properties were evaluated. Some polymers exhibited sufficient toughness for industrial use. Because diamine-type pseudo[3]rotaxane is easily obtained on a large scale (100 g in a 1 L flask) from α-CD and 1,12diaminododecane, this study contributes to the synthesis of various polyrotaxanes for actual use.

show abstract

“…Later, the team prepared [48] a head-to-tail orientational isomer with high selectively on an oligophenylene(ethynylene) dumbbell on porous glass solid supports. Selective syntheses of tail-to-tail [49,50] and head-to-head [51][52][53][54] [3]rotaxanes have also been reported (see Section 3.1.2). A [3]rotaxane based on oligothiophene-threaded β-CD rings has also been synthesized [55] as a mixture of orientational isomers.…”

Section: Methodsmentioning

confidence: 99%

Exploring and Exploiting the Symmetry-Breaking Effect of Cyclodextrins in Mechanomolecules

Bruns

2019

Symmetry

View full text Add to dashboard Cite

Cyclodextrins (CDs) are cone-shaped molecular rings that have been widely employed in supramolecular/host–guest chemistry because of their low cost, high biocompatibility, stability, wide availability in multiple sizes, and their promiscuity for binding a range of molecular guests in water. Consequently, CD-based host–guest complexes are often employed as templates for the synthesis of mechanically bonded molecules (mechanomolecules) such as catenanes, rotaxanes, and polyrotaxanes in particular. The conical shape and cyclodirectionality of the CD “bead” gives rise to a symmetry-breaking effect when it is threaded onto a molecular “string”; even symmetrical guests are rendered asymmetric by the presence of an encircling CD host. This review focuses on the stereochemical implications of this symmetry-breaking effect in mechanomolecules, including orientational isomerism, mechanically planar chirality, and topological chirality, as well as how they support applications in regioselective and stereoselective chemical synthesis, the design of molecular machine prototypes, and the development of advanced materials.

show abstract

Effective Synthesis and Modification of α‐Cyclodextrin‐Based [3]Rotaxanes Enabling Versatile Molecular Design

Cited by 19 publications

References 50 publications

Alcohol Moiety-Tethering Acylazides as Versatile Isocyanate Precursors for Polymerization Initiators and Monomers

Alcohol Moiety-Tethering Acylazides as Versatile Isocyanate Precursors for Polymerization Initiators and Monomers

Main Chain-Type Polyrotaxanes Derived from Cyclodextrin-Based Pseudo[3]rotaxane Diamine and Macromolecular Diisocyanate: Synthesis, Modification, and Characterization

Exploring and Exploiting the Symmetry-Breaking Effect of Cyclodextrins in Mechanomolecules

Contact Info

Product

Resources

About