TY - JOUR

T1 - Stereoselective O-Glycosylations by Pyrylium Salt Organocatalysis**

AU - Nielsen, Michael Martin

AU - Holmstrøm, Thomas

AU - Pedersen, Christian Marcus

N1 - Publisher Copyright: © 2021 Wiley-VCH GmbH

PY - 2022

Y1 - 2022

N2 - Despite many years of invention, the field of carbohydrate chemistry remains rather inaccessible to non-specialists, which limits the scientific impact and reach of the discoveries made in the field. Aiming to increase the availability of stereoselective glycosylation chemistry for non-specialists, we have discovered that several commercially available pyrylium salts catalyze stereoselective O-glycosylations of a wide range of phenols and alkyl alcohols. This catalytic reaction utilizes trichloroacetimidates, an easily accessible and synthetically proven electrophile, takes place under air and only initiates when all three reagents are mixed, which should provide better reproducibility by non-specialists. The reaction exhibits varying degrees of stereospecificity, resulting in β-selective glycosylations from α-trichloroacetimidates, whilst an α-selective glycosylation proceeds from β-trichloroacetimidates. A mechanistic study revealed that the reaction likely proceeds via an SN2-like substitution on the protonated electrophile.

AB - Despite many years of invention, the field of carbohydrate chemistry remains rather inaccessible to non-specialists, which limits the scientific impact and reach of the discoveries made in the field. Aiming to increase the availability of stereoselective glycosylation chemistry for non-specialists, we have discovered that several commercially available pyrylium salts catalyze stereoselective O-glycosylations of a wide range of phenols and alkyl alcohols. This catalytic reaction utilizes trichloroacetimidates, an easily accessible and synthetically proven electrophile, takes place under air and only initiates when all three reagents are mixed, which should provide better reproducibility by non-specialists. The reaction exhibits varying degrees of stereospecificity, resulting in β-selective glycosylations from α-trichloroacetimidates, whilst an α-selective glycosylation proceeds from β-trichloroacetimidates. A mechanistic study revealed that the reaction likely proceeds via an SN2-like substitution on the protonated electrophile.

U2 - 10.1002/anie.202115394

DO - 10.1002/anie.202115394

M3 - Journal article

C2 - 34847269

AN - SCOPUS:85121674831

VL - 61

JO - Angewandte Chemie International Edition

JF - Angewandte Chemie International Edition

SN - 1433-7851

IS - 6

M1 - e202115394

ER -