ENCAT · Synthesis of new Schiff base derived catalysts: application towards enantioselective reactions in greener and more sustainable media
FP7 — People (Marie Curie Actions)
- Duration
- 2009-12-03 → 2012-12-02
- EU contribution
- €45,000
- Participants
- 1
- Scheme
- MC-ERG
Lines connect the coordinator with its partners.
Results in brief
Synthesis of new Schiff base derived catalysts: application towards enantioselective reactions in greener and more sustainable media
The epoxidation reaction is one of the most interesting and versatile tools in organic chemistry, especially in multi-step synthesis. Even if the epoxide is not the final target molecule, it gives access to numerous compounds. Its versatility comes from the fact that two potential stereogenic centres may be controlled in the same reaction. Considering this crucial importance, many catalytic systems and experimental conditions have been evaluated over the past 20 years. Unfortunately, the results obtained to date still suffer from major drawbacks. The latter are often related to a tedious and costly synthesis (i.e. porphyrins), a limited stability (i.e. salens) and/or require the use of non-environmentally friendly oxidant. The ENCAT project (November 2009-October 2010) aimed at developing a new series of readily affordable ligands that could be used for complexing non-toxic metals and evaluate the catalytic activity of the new complex for the epoxidation of terminal olefins in an environmentally friendly medium. To this end, we undertook the preparation of new pyrrole-containing salen type ligands that were hoped to display a catalytic activity as high as the parent salens whilst displaying an enhanced stability (Scheme 1). The synthetic strategy was validated and a series of three new ligands were prepared. The manganese complexes were synthesized and their catalytic activity was evaluated towards the H2O2 and PhIO-mediated epoxidations of three olefins, namely cyclooctene, styrene, and alpha-pinene. These studies revealed that: 1) these new systems display a strong catalase activity when H2O2 is used as terminal oxidant; and 2) a promising activity when PhIO is used as terminal oxidant (see the draft that has just been accepted for publication in Dalton Transactions). Physicochemical characterisations were carried out by colleagues from the Inorganic Laboratory at the University of Orsay for understanding the intrinsic mechanisms and structural factors that control the catalytic activity. Based on those findings, the synthesis of a new series of ligands was planned but as Dr SZYDLO succeeded in getting a full-time job in a private company (early November 2010), the ENCAT project had to be ended by anticipation after 12 months. However, this project will be further continued in a different frame.
Data: CORDIS, © European Union
Project objective
Over the past few years, the need for greener processes in chemical industries has considerably grown up. In order to solve the issue of organic solvents, non-pollutants media such as water, fluorinated solvents and supercritical fluids (SCFs) have attracted increasing attention. Beside, the demand for enantiopure compounds in the life sciences has stimulated interest in asymmetric catalysis. So the use of asymmetric catalysts in green solvents holds much promise for the development of sustainable chemical manufacturing. Among numerous catalysts, Schiff base complexes of metal ions show high catalytic activity and are commonly used in various reactions but the employment of these catalysts in environmentally friendly solvents still rare particularly for asymmetric catalysis. Also we propose to develop new chiral Schiff base complexes, which can be used in supercritical fluids and perfluorinated solvents. We will focus on supercritical carbon dioxide (scCO2). One of the challenges of the proposal consists in obtaining soluble ligands in these media. The synthesis of ligands with hydrocarbon or fluorocarbon chains should solve this issue. Another concept that will be envisaged is the use of water-soluble catalysts in scCO2-water biphasic systems by addition of hydrophilic arms on the ligands. The ligands will be synthesized in few steps by condensation of primary amines and aldehydes to match the demand of low-cost, environmentally friendly, and rapid synthesis. After complexation with metals, reactions such as oxidation, epoxidation and aldolisation will be studied as well as the recovery and reuse of the catalysts. Particularly, small cyclic ether molecules will be engaged in enantioselective reactions as models to develop useful methodologies in the synthesis of bioactive cyclic ethers. Finally, our objective is to bring efficient tools for the chemists worldwide to transfer the asymmetric catalysis methodology to large-scale synthesis technology.
Original text from CORDIS.
Participants
- UNIVERSITE LYON 1 CLAUDE BERNARD · Villeurbanne CedexCoordinatorFrance
Links
Data: CORDIS, © European Union