Chemicals were purchased from Sigma Aldrich, abcr GmbH, Fisher, or TCI and used without further purification. Where specified, solvents were dried over 3 Å molecular sieves for at least 48 h. Biotransformations were carried out in a COY chamber, using degassed buffers and solvents. GDH-101 was provided by Johnson Matthey (JM). NMR spectra were recorded on an Agilent 400/54 Premium Shielded Spectrometer; 1 H-spectra referenced relative to TMS, C-spectra referenced using absolute referencing relative to the corresponding 1 H-spectrum. EREDs were produced in E. coli BL21 Gold(DE3) and purified by immobilised metal affinity chromatography, as previously described. Vinyl sulfides 2a to 2g were synthesised based on literature. Further details can be found in the electronic supporting information.