Iridium-promoted deoxyglycoside synthesis: stereoselectivity and mechanistic insight

Pal, Kumar Bhaskar; Guo, Aoxin; Das, Mrinmoy; Lee, Jiande; Báti, Gábor; Yip, Benjamin Rui Peng; Loh, Teck‐Peng; Liu, Xuewei

doi:10.1039/d0sc06529c

Cited by 13 publications

(4 citation statements)

References 72 publications

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“…Catalyzing the direct addition of an alcohol to a glycal is the most atom‐efficient route to 2‐deoxyglycosides [17] . Over the past few years, numerous chemists have made outstanding contributions to the synthesis of 2‐deoxysugar using various organocatalysts, [17b–h] as well as metal catalytic activators [17j–p] …”

Section: Introductionmentioning

confidence: 99%

L‐Proline Derived Thioamide Small Organic Molecule for the α‐Stereoselective Synthesis of 2‐Deoxyglycosides

et al. 2023

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L‐Prolinethioamide catalyzes direct stereoselective glycosylation of glycal donors to access 2‐deoxyglycosides under moderate reaction conditions. This proposed glycosylation protocol produced the desired products in up to 88% yield and shows greater tolerance of glycosyl acceptors and a broad substrate scope with better stereoselectivity. This method is also applicable for less nucleophilic acceptors such as phenol. In addition, 1,1′‐linked trehalose‐type analogues can also be accessed through this methodology. Further, mechanistic studies suggest that, in this glycosylation, L‐prolinethioamide operates via Brønsted acid/base catalysis.

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Section: Introductionmentioning

confidence: 99%

L‐Proline Derived Thioamide Small Organic Molecule for the α‐Stereoselective Synthesis of 2‐Deoxyglycosides

et al. 2023

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“…Generation of C−O bonds via greener and atom economical routes via purely organometallic pathways [4,6a,7g,11] has thus been a field of immense interest. While Marks has reported several examples of intramolecular O−H addition to multiple bonds, [11a–c] pioneering independent work by Goldman [4] and Hartwig [11d] has led to several recent reports [11e,12] on transition‐metal catalyzed intermolecular addition of O−H bonds across the double bond to yield ethers.…”

Section: Introductionmentioning

confidence: 99%

Pincer‐Ruthenium Catalyzed Oxygen Mediated Dehydrative Etherification of Alcohols and Ortho‐Alkylation of Phenols

2022

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In the current report, a dehydration strategy has been formulated for the selective etherification of secondary alcohols catalyzed by NNN pincer-ruthenium(II) carbonyl complexes based on bis(imino)pyridine ligands in the presence of molecular oxygen under solvent-free and base-free conditions at 140 °C. Under these conditions, very high yields (up to 92%, ca. 6133 TON) of the corresponding ethers are obtained at a very low catalyst loading (ca. 0.015 mol%). Mechanistic studies provide key evidence for the various events that occur during the catalytic cycle. While iodometric titration gives quantitative proof for the liberation of hydrogen peroxide in catalytic amounts and hence confirms the role of oxygen as a co-catalyst, DFT, HRMS, IR and 13 C NMR analysis are indicative of the non-labile nature of the ancillary CO ligand. On the other hand, DFT, NMR and HRMS studies reveal the hemi-labile nature of the pincer-ligand in the presence of oxygen. EPR analysis provide conclusive evidence for generation of Ru(III) species via single electron transfer (SET) from O 2 . Apparently the Ru(III) species ( Ph2 NN)RuCl 2 (CO)(OH) is the resting-state of the etherification reaction and several of its derivatives have been detected by HRMS analysis. The pincer-ruthenium catalyzed etherification of 1-phenyl ethanol has been successfully extended not only to various aromatic secondary alcohols but also to the cross-etherification and/or oalkylation of 1-phenyl ethanols with a variety of phenols. Readily available oxygen and tiny amounts (0.015 mol%) of pincer-Ru catalyst are the only requirement for this atom-economical and environmentally benign dehydrative etherification reaction which apparently has not been reported thus far.

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“…2-deoxysugars occur broadly in bioactive natural products and pharmaceutical agents [1][2][3]. They have been applied as clinical drugs in treating various diseases, including heart failure, cancers, and bacterial and viral infections [4][5][6][7]. However, the glycosidic bond of 2-deoxysugar is easily hydrolyzed by enzymes or acids, resulting in a short half-life in vivo, which limits its application in drug development [8,9].…”

Section: Introductionmentioning

confidence: 99%

Stereoselective Synthesis of 2-Deoxythiosugars from Glycals

et al. 2022

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2-deoxythiosugars are more stable than 2-deoxysugars occurring broadly in bioactive natural products and pharmaceutical agents. An effective and direct methodology to stereoselectively synthesize α-2-deoxythioglycosides catalyzed by AgOTf has been developed. Various alkyl thiols and thiophenols were explored and the desired products were formed in good yields with excellent α-selectivity. This method was further applied to the syntheses of S-linked disaccharides and late-stage 2-deoxyglycosylation of estrogen, L-menthol, and zingerone thiols successfully.

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Iridium-promoted deoxyglycoside synthesis: stereoselectivity and mechanistic insight

Abstract: Ir(i)-catalyzed α-selective O-glycosylation of glycals provided an access to both 2-deoxyglycosides and 2,3-unsaturated glycosides with a broad substrate scope. The underlying rationale of α-selectivity has been illustrated by the DFT study.

Cited by 13 publications

References 72 publications

L‐Proline Derived Thioamide Small Organic Molecule for the α‐Stereoselective Synthesis of 2‐Deoxyglycosides

L‐Proline Derived Thioamide Small Organic Molecule for the α‐Stereoselective Synthesis of 2‐Deoxyglycosides

Pincer‐Ruthenium Catalyzed Oxygen Mediated Dehydrative Etherification of Alcohols and Ortho‐Alkylation of Phenols

Stereoselective Synthesis of 2-Deoxythiosugars from Glycals

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