Asymmetric 1,2-oxidative alkylation of conjugated dienes via aliphatic C-H bond activation

The merging of transition-metal catalysis with radical chemistry offers a versatile platform for three-component difunctionalization of alkenes, allowing the construction of molecular complexity from readily available feedstocks. However, the direct use of hydrocarbon feedstocks as sp3-hybridized carbon radical precursors to participate in catalytic enantioselective functionalization of alkenes remains elusive. Here we describe an asymmetric 1,2-oxidative alkylation of conjugated dienes based on direct functionalization of strong and neutral C(sp3)-H bonds enabled by the combination of hydrogen atom transfer and copper catalysis. This approach allows carbon-centred radicals to be generated by selective activation of aliphatic C-H bonds, which are ubiquitous in hydrocarbons and other radical precursors. These radicals then react with 1,3-dienes to give allylic radicals which participate in copper-mediated asymmetric C-O coupling. This protocol provides a single-step access to various synthetically useful allylic esters directly from widely available chemical feedstocks. Enantioselective difunctionalization of alkenes mediated with radicals and using selective C-H bond activation remains unexplored. Now, an asymmetric 1,2-oxidative alkylation of conjugated dienes, based on direct functionalization of strong and neutral C(sp3)-H bonds, is reported using a combination of hydrogen atom transfer and copper-catalysed reactions.