Carbene-Mediated Quaternarization of the Anomeric Position of Carbohydrates: Synthesis of Allylic Ketopyranosides, Access to the Missing α-Gluco and β-Manno Stereoisomers, and Preparation of Quaternary 2-Deoxy 2-Acetamido Sugars

Mébarki, Kévin; Gavel, Marine; Heis, Floriane; Joosten, Antoine; Lecourt, Thomas

doi:10.1021/acs.joc.7b01493

Cited by 8 publications

(3 citation statements)

References 34 publications

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“…In the presence of diphenylborinic acid ( 3a , 10 mol %), quinuclidine (20 mol %) and Ir[dF(CF 3 )ppy] 2 (dtbbpy)PF 6 , ( 4 , 1 mol %), irradiation of rhamnopyranoside 1a and methyl acrylate with a blue LED in acetonitrile at 25 °C generated spiro -fused butyrolactone 2a in 72% yield (Scheme ). The structure of 2a was established by nuclear magnetic resonance (NMR) analysis ( 1 H– 1 H COSY, 1 H– 13 C HMBC and NOE difference spectra).…”

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confidence: 99%

Site-Selective and Stereoselective C–H Alkylations of Carbohydrates via Combined Diarylborinic Acid and Photoredox Catalysis

et al. 2019

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Diphenylborinic acid serves as a cocatalyst for site- and stereoselective C–H alkylation reactions of carbohydrates under photoredox conditions using quinuclidine as the hydrogen atom transfer mediator. Products arising from selective abstraction of the equatorial hydrogens of cis-1,2-diol moieties, followed by C–C bond formation with net retention of configuration, are obtained. Computational modeling supports a mechanism involving formation of a tetracoordinate borinic ester, which accelerates hydrogen atom transfer with the quinuclidine-derived radical cation through polarity-matching and/or ion-pairing effects.

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confidence: 99%

Site-Selective and Stereoselective C–H Alkylations of Carbohydrates via Combined Diarylborinic Acid and Photoredox Catalysis

et al. 2019

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“…TBAF mediated deprotection led to complete degradation. By contrast, the use of HF.pyridine smoothly gave alcohol 28 in nearly quantitative yield [33] . Finally, the tosyl group of 22 a was removed in 74 % yield by exploiting the conditions described by Ragnarsson et al.…”

Section: Resultsmentioning

confidence: 99%

“…By contrast, the use of HF.pyridine smoothly gave alcohol 28 in nearly quantitative yield. [33] Finally, the tosyl group of 22 a was removed in 74 % yield by exploiting the conditions described by Ragnarsson et al to provide the NÀ H-free oxazolidinone 29. [34] Compound 29 showed a coupling constant of 7.5 Hz between H-3 and H-4, in agreement with the literature for NÀ H-free ADGa in allal series.…”

Section: Resultsmentioning

confidence: 99%

Ferrier/Aza‐Wacker/Epoxidation/Glycosylation (FAWEG) Sequence to Access 1,2‐Trans 3‐Amino‐3‐deoxyglycosides

Geulin

Bourne‐Branchu

Ayed

et al. 2023

Chemistry A European J

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3‐Amino‐3‐deoxyglycosides constitute an essential class of nitrogen‐containing sugars. Among them, many important 3‐amino‐3‐deoxyglycosides possess a 1,2‐trans relationship. In view of their numerous biological applications, the synthesis of 3‐amino‐3‐deoxyglycosyl donors giving rise to a 1,2‐trans glycosidic linkage is thus an important challenge. Even though glycals are highly polyvalent donors, the synthesis and reactivity of 3‐amino‐3‐deoxyglycals have been little studied. In this work, we describe a new sequence, involving a Ferrier rearrangement and subsequent aza‐Wacker cyclization that allows the rapid synthesis of orthogonally protected 3‐amino‐3‐deoxyglycals. Finally a 3‐amino‐3‐deoxygalactal derivative was submitted for the first time to an epoxidation/glycosylation with high yield and great diastereoselectivity, highlighting FAWEG (Ferrier/Aza‐Wacker/Epoxidation/Glycosylation) as a new approach to access 1,2‐trans 3‐amino‐3‐deoxyglycosides.

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Discussion Addendum For: Protection of Alcohols Using 2‐Benzyloxy‐1‐Methylpyridinium Trifluoromethanesulfonate: Methyl ( R )‐(‐)‐3‐Benzyloxy‐2‐methyl Propanoate

2020

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Benzyl ethers are important protecting groups in organic synthesis, but traditional installation methods, such as the Williamson ether synthesis or reaction of an alcohol with benzyl trichloroacetimidate, often limit their formation with substrates containing functional groups unable to tolerate strongly basic or acidic conditions, respectively. The reaction of N,N‐dimethylaniline occurred via an N‐methyl to benzyl exchange instead of the expected electrophilic aromatic substitution. This illustrates that amines can also trap the putative phenylcarbenium species released during the thermal activation of 2‐benzyloxy‐1‐methylpyridinium triflate (BnOPT). Benzylation can generally be achieved chemoselectively using BnOPT with triethylamine in the presence of alcohols, amides, and other functional groups. The mild and nearly neutral conditions associated with the use of BnOPT is the main advantage of the benzylation protocol.

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Carbene-Mediated Quaternarization of the Anomeric Position of Carbohydrates: Synthesis of Allylic Ketopyranosides, Access to the Missing α-Gluco and β-Manno Stereoisomers, and Preparation of Quaternary 2-Deoxy 2-Acetamido Sugars

Cited by 8 publications

References 34 publications

Site-Selective and Stereoselective C–H Alkylations of Carbohydrates via Combined Diarylborinic Acid and Photoredox Catalysis

Site-Selective and Stereoselective C–H Alkylations of Carbohydrates via Combined Diarylborinic Acid and Photoredox Catalysis

Ferrier/Aza‐Wacker/Epoxidation/Glycosylation (FAWEG) Sequence to Access 1,2‐Trans 3‐Amino‐3‐deoxyglycosides

Discussion Addendum For: Protection of Alcohols Using 2‐Benzyloxy‐1‐Methylpyridinium Trifluoromethanesulfonate: Methyl ( R )‐(‐)‐3‐Benzyloxy‐2‐methyl Propanoate

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