# Facile Diastereoselective Synthesis of Dihydroxyadipic Acid and Dihydroxyadipic Dilactone by Catalytic Reduction of Biosourced 3‑Hydroxy-2-Pyrone-6-Carboxylic Acid

## TL;DR

This paper presents a simple and selective method to synthesize dihydroxyadipic acid and its dilactone form from a renewable chemical source.

## Contribution

The study introduces a novel catalytic reduction method for producing dihydroxyadipic acid and its dilactone with high diastereoselectivity.

## Key findings

- Catalytic hydrogenation of 3-hydroxy-2-pyrone-6-carboxylic acid yields dihydroxyadipic acid with high diastereoselectivity.
- The dilactone derivative was synthesized via intramolecular condensation and shows potential as a polymer comonomer.
- A preliminary polymerization test with the dilactone and diamine was successfully demonstrated.

## Abstract

3-Hydroxy-2-pyrone-6-carboxylic acid is a versatile chemical
easily
prepared from aldaric acids, a family of compounds obtained from renewable
resources. Herein, an efficient synthesis of dihydroxyadipic acid
by catalytic hydrogenation of this pyrone at room temperature and
atmospheric pressure is reported. The reaction performed in organic
solvents showed high diastereoselectivity, resulting in the possibility
to obtain the racemic mixture of dihydroxyadipic acid (R,R) and (S,S)
that was further converted to the dilactone 2,5-dioxabicyclo[2.2.2]­octane-3,6-dione
by a double intramolecular condensation reaction. This compound is
a promising comonomer and/or chain-extender in the synthesis of polymers.
As an example, a preliminary test of the polymerization reaction of
the dilactone in the presence of a diamine is reported.