# Phosphine Catalyzed Michael-Type Additions: The Synthesis of Glutamic Acid Derivatives from Arylidene-α-amino Esters

## TL;DR

This paper describes a phosphine-catalyzed method to synthesize glutamic acid derivatives from specific esters and alkenes.

## Contribution

The novel contribution is the use of phosphine catalysts to optimize the synthesis of glutamic acid derivatives via Michael-type additions.

## Key findings

- Phosphine catalysts enable efficient synthesis of Michael-type addition products with high purity.
- The process allows for the production of pyroglutamate derivatives in high yields through reduction and cyclization.
- Acidic hydrolysis provides a direct route to glutamate surrogates from the imino group.

## Abstract

The reaction of arylidene-α-amino esters with electrophilic alkenes to yield Michael-type addition compounds is optimized using several phosphines as organocatalysts. The transformation is very complicated due to the generation of several final compounds, including those derived from the 1,3-dipolar cycloadditions. For this reason, the selection of the reaction conditions is a very complex task and the slow addition of the acrylic system is very important to complete the process. The study of the variation in the structural components of the starting imino ester is performed as well as the expansion of other electron-poor alkenes. The crude products have a purity higher than 90% in most cases without any purification. A plausible mechanism is detailed based on the bibliography and the experimental results. The synthesis of pyroglutamate entities, after the reduction of the imino group and cyclization, is performed in high yields. In addition, the hydrolysis of the imino group, under acidic media, represents a direct access to glutamate surrogates.