Effective Production of Selected Dioxolanes by Sequential Bio- and Chemocatalysis Enabled by Adapted Solvent...

Most combinations of chemo- and biocatalysis take place in aqueous media or require a solvent change with complex intermediate processing. Using enzymes in the same organic solvent as the chemocatalyst eliminates this need. Here, it was shown that a complete chemoenzymatic cascade to form dioxolanes could be carried out in a purely organic environment. The result, including downstream processing, was compared with a classical mode, shifting solvent. First, a two-step enzyme cascade starting from aliphatic aldehydes to chiral diols (3,4-hexanediol and 4,5-octanediol) was run either in an aqueous buffer or in the potentially biobased solvent cyclopentyl methyl ether. Subsequently, a ruthenium molecular catalyst enabled the conversion to dioxolanes [e. g., (4S,5S)-dipropyl-1,3-dioxolane]. Importantly, the total synthesis of this product was not only highly stereoselective but also based on the combination of biomass, CO₂ , and hydrogen, thus providing an important example of a bio-hybrid chemical.