Assessing biocatalysis using dihydrolevoglucosenone (Cyrene™) as versatile bio-based (co)solvent

An emerging biogenic aprotic solvent is the cellulose-derived dihydrolevoglucosenone, or 6,8-dioxabicyclooctanone (Cyrene (TM)). This paper explores the use of Cyrene in lipase-catalyzed biotransformations, both in aqueous solutions - as co-solvent - as well as non-conventional media for synthesis. Cyrene is useful as organic solvent for lipophilizations using benzoic acid and glycerol as a model system for substrates with unpaired solubilities. The immobilized lipase B from Candida antarctica is active in Cyrene, yielding up to similar to 10 g product L-1. Interestingly, crosslinked aggregates immobilized lipases (CLEA) remain significantly stable in Cyrene, enabling its use along several catalytic cycles. Cyrene is highly hygroscopic and forms geminal-diol structures with water, leading to solvent mixtures with a (tailored) gradient of polarities, what may be promising for biocatalysis in aqueous solutions. CALK displays hydrolytic reactions with different proportions of Cyrene as cosolvent, and CLEA derivatives remain fully active over 6 cycles at 30 % v/v Cyrene.