Transesterification reactions are fundamental transformations in organic chemistry, yet performing them in aqueous media is challenging because of the competing hydrolysis reaction. In this study, we describe a mutant of alcohol oxidase from Phanerochaete chrysosporium (PcAOx-VPN) that also exhibits transesterification activity. Moreover, PcAOx-VPN displays no detectable hydrolytic activity, owing to its hydrophobic active site, which effectively excludes water. These characteristics make PcAOx-VPN a promising catalyst for transesterification reactions in aqueous media, a context that is typically compromised by competing hydrolysis.

This study explores a chemoenzymatic cascade to synthesise chiral β-hydroxy ketones by integrating the selective oxyfunctionalisation capabilities of peroxygenases with the carbon-carbon bond-forming progress of organocatalysts. Initial results with simple organocatalysts demonstrated poor performance due to mutual inactivation of the biocatalyst and organocatalyst. However, the use of more complex prolinamide derivatives improved the reaction efficiency and enantioselectivity, enabling a one-pot, one-step synthesis process. This methodology was further optimised to produce high yields of enantiomerically pure aldol products and was shown to be extendable to other substituted toluenes and aldol donors.

Unspecific peroxygenases (UPOs) are promising biocatalysts for oxyfunctionalisation reactions, owing to their simplicity of handling, stability and robustness. A limitation of using UPOs on a large scale is their deactivation in the presence of even rather modest concentrations of H₂O₂, requiring a constant and controlled supply of low amount of H₂O₂. Herein, we report an organometallic complex [Cp*Ir(pica)NO₃] {pica=picolinamidate=κ²-pyridine-2-carboxamide ion (−1)} 1 capable of efficiently regenerating FMNH₂ from FMN (TOF=350 h⁻¹, 298 K), driven by NaHCOO; FMNH₂, in turn, spontaneously reacts with O₂ leading to H₂O₂. After having studied the compatibility of 1 with the UPO from Agrocybe aegerita (rAaeUPO PaDa-I) and individuated the best experimental conditions, we applied such a hybrid catalytic tandem in some hydroxylation, epoxidation and sulfoxidation reactions. Best performances were obtained by using a 1/rAaeUPO molar ratio of 50. TONs for the biocatalyst of up to 18933 were obtained for the transformation of ethylbenzene derivatives into (R)-1-phenylethanols (ee>99 %). 1/rAaeUPO was found to oxidise also cis-methyl styrene (TON=13488), leading exclusively (1R,2S)-cis-methyl styrene oxide (ee>99 %), cyclohexane (TON=1634) and thioanisole (TON=1369).