Application of Deep Eutectic Solvents in Promiscuous Lipase‐Catalysed Aldol Reactions

Abstract The application of deep eutectic solvents has been demonstrated for the first time in promiscuous lipase‐catalysed aldol reactions. The model reaction between 4‐nitrobenzaldehyde and acetone was examined in depth, with excellent compatibility being found between porcine pancreas lipase and choline chloride/glycerol mixtures for the formation of the aldol product in high yields. The system was compatible with a series of aromatic aldehydes and ketones including acetone, cyclopentanone and cyclohexanone. In some cases, the corresponding α,β‐unsaturated carbonyl compounds were found as minor products. Control experiments demonstrate that the enzymatic preparation was also responsible for a collateral dehydration reaction once the aldol product is formed.