# Selective Acetylation of Unprotected Thioglycosides and Fully Unprotected Monosaccharides with Candida antarctica Lipase‑B

## TL;DR

Researchers developed a new method using an enzyme to selectively acetylate sugars, improving the synthesis of protected saccharides.

## Contribution

A novel enzymatic acetylation method using Candida antarctica lipase-B for selective sugar protection was developed.

## Key findings

- Enzymatic acetylation of thio-d-galactopyranoside at positions 2 and 6 was successfully achieved.
- Improved synthesis methods for known saccharides like d-glucose and l-rhamnose were discovered.
- Enzymatic acetal formation between positions 4 and 6 was identified as a new reaction pathway.

## Abstract

A selective enzymatic acetylation method for the protection
of
the second and the sixth positions of thio-d-galactopyranoside
was found using immobilized Candida antarctica lipase-B (CAL-B). Unfortunately, it was determined that the immobilized
enzyme cannot be recycled effectively. The optimized acetylation method
was screened with different thioglycosides and with fully unprotected
saccharides. New methods for several new partially protected saccharides
were found, while the synthesis of some known saccharides, e.g., the
third and the sixth position-protected d-glucose or the fourth
position-protected l-rhamnose, was improved. Furthermore,
an enzymatic acetal formation between the fourth and the sixth positions
was discovered. The main limitation for acetylation reactions with
CAL-B has been determined to be the substrate solubility.