Oxidative metal-free C-C bond activation of a β-β lignin model compound by H2O2/HCOOH system

We report the first example of an oxidative C-C bond activation with the H2O2/HCOOH system in a beta-beta lignin model compound. Selective hemi (synthesis) of acuminatolide from sesamin in good yield (87 %) was achieved without any metal catalyst under an easy-to-handle and accessible protocol. As a side product, 2,5-dihydroxy-1,4-benzoquinone was identified and confirmed in the sesamin reaction as the destination of the aromatic fragment lost in C-Ph-C-alpha bond activation; the use of guaiacol and phenol as complementary model compounds support this proposal. An excess of H2O2/HCOOH (20 equiv. Respect to sesamin) is needed, owing to the decomposition pathways of both oxidants. However, system advantages and applications considering H2O2 low cost, HCOOH potential production from biomass, and direct incorporation of new functional groups are important features.