# Triphenylphosphine‐Catalyzed Synthesis of β‐Thiopropionate Thioesters or Esters via the Reaction of Maleic Anhydride with Thiols and Alcohols

## TL;DR

This paper describes a new method using triphenylphosphine to efficiently synthesize β-thiopropionate thioesters or esters from maleic anhydride and thiols or alcohol/thiol mixtures.

## Contribution

The study introduces a novel one-pot catalytic method for synthesizing β-thiopropionate derivatives using triphenylphosphine.

## Key findings

- A unique product is formed when two different thiols react with maleic anhydride in a single step.
- The reaction proceeds in two steps when an alcohol/thiol mixture is used.
- Triphenylphosphine catalyzes the decarboxylative ring-opening of maleic anhydride efficiently.

## Abstract

In this study, the one‐pot reaction of maleic anhydride with a combination of aromatic and aliphatic thiols, or with an alcohol and thiol mixture, in the presence of triphenylphosphine catalyst has been investigated. The reaction with the mixture of thiols occurs in a single step, and despite the presence of two different thiols in the reaction medium, a unique product is formed. The aromatic thiol facilitates the ring‐opening of the anhydride, while the aliphatic thiol participates solely in the Michael addition to the intermediate. When a mixture of alcohol and thiol is used in the medium, the reaction proceeds in two steps. In this reaction, the alcohol opens the anhydride ring, and the thiol induces nucleophilic addition to the acrylate intermediate.

Decarboxylative ring‐opening of maleic anhydride with a combination of aromatic and aliphatic thiols or an alcohol/thiol mixture for the synthesis of β‐thiopropionate thioesters or esters, catalyzed by triphenylphosphine.© 2025 WILEY‐VCH GmbH