A 2,4-O-[(Z)-2-butenylene]-bridged glucopyranose: efficient construction of the bicyclic skeleton and its axial-rich twist-boat conformation

Cao, Yang; Kasai, Yusuke; Bando, Masafumi; Kawagoe, Mayumi; Yamada, Hidetoshi

doi:10.1016/j.tet.2009.01.019

Cited by 9 publications

(5 citation statements)

References 32 publications

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“…With this consideration in mind, we chose an EDB group. The glycosylation reaction using the EDB-bridged glucosyl fluoride 8 afforded the corresponding glucosides with a selectivity even at room temperature [supplementary material sections 2 and 19 to 24 (SM-2, - [19][20][21][22][23][24]]. The reaction proceeded through the corresponding oxocarbenium ion intermediate, as similar a selectivities were observed with 8-a and 8-b (SM-15, -16).…”

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confidence: 91%

“…On the other hand, the attachment of a bridge between the two discontiguous oxygen atoms on the pyranose ring produces a bicyclic skeleton in which the newly formed ring modulates the conformation of the pyranose scaffold. A short bridge locks the conformation into a motif with more axial substituents, as seen in 5 and 7 (18) and others (19)(20)(21)(22)(23). By contrast, when the O-3 and O-6 atoms were bridged by the EDB group, the pyranose conformation was modified by subtle structural alteration (Fig.…”

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confidence: 99%

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Conformationally supple glucose monomers enable synthesis of the smallest cyclodextrins

Ikuta

Hirata

Wakamori

et al. 2019

Science

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Cyclodextrins (CDs) are cyclic oligomers of α-1,4-d-glucopyranoside and are known mainly as hexamers to octamers. The central cavities of CDs can retain small molecules, enabling diverse applications. The smallest members, CD3 and CD4, have ring sizes too small to permit the most stable conformations of glucopyranose and have not been accessible synthetically. In this study, we present methods to chemically synthesize both CD3 and CD4. The main factor in the successful synthesis is the creation of a glucopyranose ring conformationally counterbalanced between equatorial- and axial-rich forms. This suppleness is imparted by a bridge between O-3 and O-6 of glucose, which enables the generation of desirable, albeit deformed, conformers when synthesizing the cyclic trimer and tetramer.

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confidence: 91%

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confidence: 99%

Conformationally supple glucose monomers enable synthesis of the smallest cyclodextrins

Ikuta

Hirata

Wakamori

et al. 2019

Science

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“…Based on the above observations, superarmed glycosyl donors were introduced. , Equatorial hydroxyl groups are protected with bulky silyl protective groups, inducing a ring-flip, which increases the reactivity by 3 orders of magnitude . A similar increase in reactivity is also achievable by other means, e.g., 3,6- O -tethering , and molecular levers . In this work, a molecular conformational switch, which can induce a ring-flip, is presented.…”

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confidence: 98%

Conformationally Switchable Glycosyl Donors

Holmstrøm

Pedersen

2019

J. Org. Chem.

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Glycosyl donors functionalized with 2,2′-bipyridine moieties on the 3-OH and 6-OH or the 2-OH and 4-OH undergo a conformational change when forming 1:1 complexes with Zn2+ ions. The pyranoside ring of the zinc complexes adopted axial-rich skew boat conformations. The reactivities of the two glycosyl donors were investigated by performing a series of glycosylations in the presence or absence of Zn2+ ions. These glycosylations suggested a decrease in reactivity when binding Zn2+. The conformational effect of binding Zn2+ was therefore studied using a third glycosyl donor, unable to undergo conformational changes when binding Zn2+. From competition experiments, it was observed that the binding-induced conformational change increased the reactivity slightly compared to the glycosyl donor unable to undergo a conformational change.

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“…Despite the power of this approach, the tethering of the conformationally restricting group between O-3 and O-5 complicates the synthesis of structures in which O-5 of the β-Ara f residues is further modified (see Figure A). We therefore envisioned an approach to these targets in which the conformation of the ring is locked with a 2,3- O -xylylene group ( 6 − 8 , Scheme ). , It was anticipated that oxacarbenium ions generated from these thioglycosides would adopt conformations favoring β-Ara f formation. We report here the methodology using this new donor type and its application to the synthesis of a mycobacterial arabinan fragment.…”

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confidence: 99%

β-Selective Arabinofuranosylation Using a 2,3-O-Xylylene-Protected Donor

Imamura

Lowary

2010

Org. Lett.

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Reported is a novel stereoselective beta-arabinofuranosylation that makes use of a conformationally restricted 2,3-O-xylylene-protected arabinofuranosyl donor. Optimization of the reaction conditions showed that factors including the structure of the acceptor alcohol, substrate concentration, and protecting group on O-5 of the donor affect the stereochemical outcome of the glycosylation. To demonstrate the utility of the methodology, the synthesis of an oligosaccharide fragment from the mycobacterial cell wall polysaccharide lipoarabinomannan was carried out.

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A 2,4-O-[(Z)-2-butenylene]-bridged glucopyranose: efficient construction of the bicyclic skeleton and its axial-rich twist-boat conformation

Cited by 9 publications

References 32 publications

Conformationally supple glucose monomers enable synthesis of the smallest cyclodextrins

Conformationally supple glucose monomers enable synthesis of the smallest cyclodextrins

Conformationally Switchable Glycosyl Donors

β-Selective Arabinofuranosylation Using a 2,3-O-Xylylene-Protected Donor

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