Zirconium-catalysed hydrosilylation of esters and depolymerisation of polyester plastic waste

Marie Kobylarski (1) , Liam Donnelly (1) , Jean-Claude Berthet (1) , Thibault Cantat (1)

1 LCMCE - Laboratoire de Chimie Moléculaire et de Catalyse pour l'Energie (ex LCCEF)

Schwartz's reagent, Cp2Zr(H)Cl, has traditionally been used as a stoichiometric reagent for the reduction of unsaturated organic molecules. Recently, methods to use Cp2Zr(H)Cl as a catalyst have been developed through turnover of the [Zr]–X intermediates, formed upon reaction with an organic substrate, by hydride reagents. Herein, we report the development of a new catalytic pathway for the reduction of esters that uses the bench-stable silane Me(OMe)2SiH (DMMS) as a mild stoichiometric reductant and Cp2Zr(H)Cl as the catalyst. This system exploits the regeneration of [Zr]–H through the σ-bond metathesis of [Zr]–OR with [Si]–H to achieve catalyst turnover. These reaction conditions tolerate a range of reducible functional groups (e.g. alkyne, alkene, and nitro) and give high yields of the corresponding alcohols (up to 91% isolated yield). This methodology also proved fruitful for the reductive depolymerisation of a variety of polyesters found in household plastic waste.

Domains: Material chemistry; Catalysis

Marie Kobylarski, Liam Donnelly, Jean-Claude Berthet, Thibault Cantat. Zirconium-catalysed hydrosilylation of esters and depolymerisation of polyester plastic waste. Green Chemistry, 2022, 24, pp.6810-6815. ⟨10.1039/D2GC02186B⟩. ⟨cea-03772514⟩