A robust and tunable halogen bond organocatalyzed 2-deoxyglycosylation involving quantum tunneling

Xu, Chunfa; Rao, V. U. Bhaskara; Weigen, Julia; Loh, Charles C. J.

doi:10.1038/s41467-020-18595-2

Cited by 54 publications

(37 citation statements)

References 104 publications

(203 reference statements)

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“…The additional control experiment was carried out to show the importance of XB in the present catalysis (Scheme 4). When the reaction was performed in optimal condition with 5 mol% of TBAI (tetrabutylammonium iodide), a halogen‐bond disruptor, [8j] which provided almost no reaction. Based on these observations, a plausible key intermediate structure for the present reaction was constructed and optimised at the M06‐2X/6‐31G(d,p) (def2‐TZVP for iodine) level of theory in toluene within Gaussian 16, with structures generated by GaussView 6 (Figure 5).…”

Section: Resultsmentioning

confidence: 99%

Chiral Binaphthyl‐Based Iodonium Salt (Hypervalent Iodine(III)) as Hydrogen‐ and Halogen‐Bonding Bifunctional Catalyst: Insight into Abnormal Counteranion Effect and Asymmetric Synthesis of N,S‐Acetals

et al. 2022

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Asymmetric construction of chiral N,S‐acetal skeletons is important because they are widely present in natural products and pharmaceuticals. Halogen‐bonding is a unique interaction that has been an organic synthesis focus, although research into chiral variants is limited. Halonium salts have been found to act as halogen‐bonding catalysts and asymmetric catalysis using chiral bromonium salts under basic conditions was recently discovered by our group. Herein, we report the asymmetric syntheses of chiral N,S‐acetals in good‐to‐excellent yields and enantioselectivities (82–97% ee) through bulky thiol additions to imines catalysed by a chiral iodonium salt under neutral conditions. The reaction mechanism was studied using NMR experiments and DFT calculations of a plausible intermediate, which revealed that the imine substrate is activated by the catalyst in a bidentate manner. The abnormal counteranion effect observed for the tetrakis[3,5‐bis(trifluoromethyl)phenyl]borate anion in the present system was examined by 1H NMR spectroscopy.

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Section: Resultsmentioning

confidence: 99%

Chiral Binaphthyl‐Based Iodonium Salt (Hypervalent Iodine(III)) as Hydrogen‐ and Halogen‐Bonding Bifunctional Catalyst: Insight into Abnormal Counteranion Effect and Asymmetric Synthesis of N,S‐Acetals

et al. 2022

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“… Xu et al (2020 ) reported noncovalent halogen bonding (XB) catalyzed α-stereoselective 2-deoxyglycosylation based on d -glycals (IV in Scheme 13 ). This report described the use of noncovalent XB catalyst ( 137 ) for the glycosylation using a variety of d -glycals ( 122 ) of numerous different acceptors which resulted in the corresponding 2-deoxyglycosides ( 124 ) in excellent yields and α-stereoselectivity.…”

Section: Techniques For 12- Cis Glycosylation Reac...mentioning

confidence: 99%

Recent Advances in Stereoselective Chemical O-Glycosylation Reactions

Mukherjee

Ghosh

Hanover

2022

Front. Mol. Biosci.

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Carbohydrates involving glycoconjugates play a pivotal role in many life processes. Better understanding toward glycobiological events including the structure–function relationship of these biomolecules and for diagnostic and therapeutic purposes including tailor-made vaccine development and synthesis of structurally well-defined oligosaccharides (OS) become important. Efficient chemical glycosylation in high yield and stereoselectivity is however challenging and depends on the fine tuning of a protection profile to get matching glycosyl donor–acceptor reactivity along with proper use of other important external factors like catalyst, solvent, temperature, activator, and additive. So far, many glycosylation methods have been reported including several reviews also. In the present review, we will concentrate our discussion on the recent trend on α- and β-selective glycosylation reactions reported during the past decade.

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“…A similar type of catalyst (157) was used in the preparation of 2-deoxyglycosides in high α-selectivity from glucals and various glycosyl acceptors. 53 Also, in this case, the use of tetraisopropyldisiloxane as the protecting group in the case of glucals was necessary (Scheme 23). According to the authors, after extensive investigation, a complex reaction network of multiple dynamic interactions is operative.…”

Section: Organic and Biomolecular Chemistry Reviewmentioning

confidence: 99%