Advances in deep eutectic solvents and water: applications in metal- and biocatalyzed processes, in the synthesis of APIs, and other biologically active compounds

Abstract

This review highlights recent advances in metal- and biocatalyzed transformations, in the synthesis of APIs and other biologically active compounds, when employing deep eutectic solvents and water as environmentally responsible solvents.

Scalable Negishi Coupling between Organozinc Compounds and (Hetero)Aryl Bromides under Aerobic Conditions when using Bulk Water or Deep Eutectic Solvents with no Additional Ligands

“…With regard to 2 a , very good to excellent yields (70–98 %) of the desired coupled products ( 3 – 16 ) were obtained when using water for the aryl bromides bearing an aldehyde, a ketone, an ester, a nitrile, an alcohol, or a nitro functional group at the ortho ‐, meta ‐, and para ‐positions, or additional halogens such as fluorine or chlorine. Particularly noteworthy was the lack of sensitivity of the alcohol moiety to the “on‐water” reaction conditions ( 15 , 16 : 75–84 % yield), [5b,f] as it was found that the substrates with functional groups containing hydrogens, whose acidity was comparable to that of water, were unresponsive under micellar conditions [9c] . All of these products could not be prepared by subjecting n ‐BuLi, in place of 2 a , to the Pd‐catalyzed cross‐coupling reactions “on water”, as reported [12g] .…”

“…Increasing environmental awareness has pressured chemists, both in academia and in industry, to become more proactive in addressing public concerns that are related to the environmental effects of reagents, products, and solvents during their use and as waste, and to drive the field of synthetic chemistry toward more green practices [4] . In this vein, the past decade has witnessed a flourish in the number of papers dealing with transition metal‐catalyzed cross‐coupling reactions run in less environmentally impactful reaction media, such as bio‐based solvents [e.g., glycerol, 2‐methyltetrahydrofuran (2‐MeTHF), γ‐valerolactone, Deep Eutectic Solvents (DESs)], [5] and aqueous media [5f, 6] …”

“…The yield of the nitro derivative 48 could also be improved in DES from 65 to 78 %. As testified by the recent literature, although sharing some physicochemical properties (e.g., a strong H‐bonded network), water and DES have been proven to be not on the same ground as far as the reactivity of the organometallic compounds is concerned [5b,f, 12g, 20] . Thus, they can advantageously and complementarily be used in organometallic chemistry.…”

Enzymatic Polymerization of Dihydroquercetin (Taxifolin) in Betaine-Based Deep Eutectic Solvent and Product Characterization

“…DESs are characterized by low volatility, high thermal stability, conductivity, and low toxicity; additionally, they are biodegradable. Another advantage of DESs over ILs is the ease of preparation and the ability to vary their physicochemical properties depending on the nature of the HBA or HBD, the molar ratio of the components, and the water content [5][6][7][8][9][10][11]. DESs have low (almost zero) vapor pressure and are viscous liquids.…”

Effective asymmetric preparation of (R)-1-[3-(trifluoromethyl)phenyl]ethanol with recombinant E. coli whole cells in an aqueous Tween-20/natural deep eutectic solvent solution

“…Natural deep eutectic solvents (NADESs), a class of emerging non-conventional solvents, have been employed in many fields due to their advantages including environmentally friendly, easy to prepare and good biocompatibility (Hansen et al 2021 ). In the process of biocatalytic reactions, it has been reported that NADESs have some functions such as improving cell membrane permeability, facilitating the mass transport and alleviating substrate inhibition (Cicco et al 2021 ; Gotor-Fernandez and Paul 2019 ; Panic et al 2021 ; Patzold et al 2019 ; Perna et al 2020 ). NADES was typically composed of a hydrogen bond acceptor (HBA, such as choline chloride (ChCl)), and a hydrogen bond donor (HBD, such as polyols, carboxylic acids, amino acids, or sugars) (Benvenutti et al 2019 ).…”