Natural eutectogels: sustainable catalytic systems for C–C bond formation reactions†
Natural eutectogels were prepared by combining the properties of amino acids with the ones of deep eutectic solvents. The soft materials obtained were fully characterised by determining the gel–sol transition temperatures and analysing the mechanical and morphological features through rheological measurements and polarised optical microscopy. All eutectogels were tested as catalytic reaction media for the enantioselective aldol reaction and the best performing one was also used to carry out the Michael addition. In both cases, eutectogels proved to have great potential as sustainable reaction media, allowing them to perform processes under mild conditions, affording excellent yields and, in some cases, also good enantiomeric excess. Catalytic soft materials can be reused up to five cycles keeping the stereochemical control of the reaction and using a recommended solvent by recent sustainable solvent guidelines.