# Copper(II) Trifluoromethanesulfonate as an Efficient, Versatile, and Dual-Purpose Catalyst for the Regioselective Acetylation of l‑Sorbose under Neat and Solvent-Directed Conditions

## TL;DR

Copper(II) trifluoromethanesulfonate efficiently and selectively catalyzes the acetylation of l-sorbose under different solvent conditions.

## Contribution

A dual-purpose catalyst enables regioselective acetylation of l-sorbose with solvent-controlled outcomes.

## Key findings

- Copper(II) trifluoromethanesulfonate catalyzes acetylation of l-sorbose efficiently.
- Solvent-free conditions favor open-chain products, while coordinating solvents favor cyclic derivatives.
- The catalyst enables selective and sustainable synthesis of sugar derivatives.

## Abstract

Herein, we report that copper­(II) trifluoromethanesulfonate
[Cu­(OTf)2], a stable, versatile, and dual-purpose catalyst,
efficiently catalyzed the acetylation of l-sorbose under
various conditions following metal trifluoromethanesulfonate screening.
Regioselectivity is critically governed by solvents: solvent-free
reactions favor the open-chain keto-sorbopentaacetate,
whereas coordinating solvents direct acetylation toward the cyclic
α-l-sorbopyranosyl tetraacetate. These findings underscore
the pivotal role of solvents in steering reaction pathways, enabling
selective and sustainable synthesis of structurally distinct sugar
derivatives while using a minimal amount of catalysts.