Glycosidic bond formation in aqueous solution: on the oxocarbenium intermediate

Area of Science:

• Computational Chemistry
• Biophysical Chemistry
• Organic Chemistry

Background:

• Glycosidic bond formation is crucial in carbohydrate chemistry and biology.
• Understanding reaction mechanisms aids in designing synthetic pathways and predicting reactivity.

Purpose of the Study:

• To elucidate the specific acid-catalyzed mechanism of glycosidic bond formation between methanol and alpha-d-glucopyranoside.
• To characterize the reaction intermediate and its properties in aqueous solution.

Main Methods:

• Car-Parrinello molecular dynamics simulations were employed.
• Simulations were conducted in aqueous solution at 300 K.

Main Results:

• The reaction proceeds through a non-solvent equilibrated oxocarbenium cation intermediate.
• This intermediate is characterized by the loss of a hydrogen-bonding interaction between the ring oxygen and water.
• The reaction mechanism was identified as D(N)A(N).

Conclusions:

• The study provides detailed insights into the molecular-level mechanism of acid-catalyzed glycosylation.
• The findings contribute to the fundamental understanding of carbohydrate chemistry and reaction dynamics.