The first examples of reductive depolymerization of lignin are reported under metal-free conditions. Using hydrosilanes as reductants and B(C₆F₅)₃ as a Lewis acid catalyst, wood lignin is efficiently converted to a narrow distribution of phenol derivatives at room temperature. A three-step methodology based on the selection of the wood species and the lignin extraction method followed by a convergent reductive depolymerization enables the production of four structurally defined aromatic compounds. The phenol products were successfully isolated in 7–24 wt% yield from lignin and 0.5–2.4 wt% yield from wood. The strategy is found to be robust and is applied to 15 different wood plants, including gymnosperm and angiosperm species. The efficiency of this novel methodology has been evaluated based on spectroscopic characterization of the lignin preparations and isolated yields of mono-aromatic products.

The first metal-free reduction of lignin model compounds is described. Using inexpensive PMHS and TMDS hydrosilanes as reductants, α-O-4 and β-O-4 linkages are reduced to primary alcohols and phenols under mild conditions using B(C₆F₅)₃as an efficient catalyst.