During the last three decades the use of hydrolases for the catalysis of environmentally friendly organic processes under mild reaction conditions has been well documented. Hydrolases have shown themselves to be ideal tools for the acceleration of synthetic transformations because of their high stability, catalytic efficiency, commercial availability and broad substrate specificity in a wide spectrum of biocatalyzed processes. In recent years, novel examples have appeared related to non-conventional reactions catalyzed by hydrolytic enzymes. Amongst these, lipases and acylases have gained much attention as promiscuous biocatalysts showing good levels of reactivity in C–C bond formation, C–heteroatom bond formation, oxidative processes, and novel hydrolytic reactions. This critical review covers recent investigation in the field of catalytic promiscuity, and highlights the most surprising and uncommon activities that this class of enzymes shows in organic synthetic transformations (111 references).

A series of synthetic nicotinamide cofactors were synthesized to replace natural nicotinamide cofactors and promote enoate reductase (ER) catalyzed reactions without compromising the activity or stereoselectivity of the bioreduction process. Conversions and enantioselectivities of >99% were obtained for C═C bioreductions, and the process was successfully upscaled. Furthermore, high chemoselectivity was observed when employing these nicotinamide cofactor mimics (mNADs) with crude extracts in ER-catalyzed reactions.

Deep eutectic solvents (DES) are a class of neoteric solvents used in multiple applications amongst which biocatalytic processes. Due to its simple preparation, low cost and inherent biodegradable properties, its use as a non-volatile biocompatible co-solvent with both whole cells and isolated enzymes has displayed increased enzyme activity and stability translating to higher product conversions and a surprising higher enantioselectivity in a range of biotransformations. This review lays out the latest updates on the use of DES in redox biocatalytic reactions. With that purpose, a clear division has been made to summarize the application of DES in bioreduction reactions using whole cells and purified alcohol dehydrogenases, oxidations involving alcohol dehydrogenases, heme-dependent enzymes, peroxidases, laccases and catalases, ozonolysis reactions, and finally mention the application of lipase in the mediation of chemoenzymatic epoxidation and Baeyer-Villiger reactions.