A Biocatalytic Platform for the Synthesis of Organofunctional Silanes and Siloxanes

Organofunctional silanes are highly useful reagents in material science, functioning as effective crosslinking agents and adhesion promoters. Traditionally, their synthesis relies on precious transition-metal catalysts, which require downstream purification and increase overall costs. Herein, we present a green and sustainable biocatalytic platform for the enantioselective synthesis of diverse organofunctional silanes bearing ester and cyano groups. Directed evolution of Thermus amyloliquefaciens protoglobin (TamPgb) produced efficient enzymes for cyclopropanation of vinyl silanes and siloxanes using diazo compounds and N-tosylhydrazones as carbene precursors with excellent diastereo- and enantiocontrol (up to 2500 TTN, >99% dr, >99% ee). Notably, we demonstrate for the first time that N-tosylhydrazones can serve as carbene precursors in enzymatic reactions, providing a safer and more practical alternative for industrial applications.