Non-Conventional Media as Strategy to Overcome the Solvent Dilemma in Chemoenzymatic Tandem Catalysis

The amazing potential of multi-catalytic cascade reactions to reduce the number of reaction steps and to solve synthetic problems brings the challenge of an increasing complexity that must be controlled. Particularly chemo-enzymatic reactions are prone to conflicts regarding different optimal reaction conditions for chemical and biological catalysts. The preference of many chemical catalysts for hydrophobic (and often water-free) solvent and of many enzymes for water poses a solvent dilemma. Recently, non-conventional solvents have been very successful to provide suitable reaction media for catalysts that otherwise require very different solvents, and to alleviate fundamental problems such as the low solubility of many substrates in aqueous solvents. In the last few years, several examples underlined the considerable potential of ionic liquids and deep eutectic solvents for the engineering of cascade reactions. This mini-review showcases the recent developments on the implementation of the so-called non-conventional media in such processes.