Copper-catalyzed radical cascades of para-quinone methides with AIBN and HO via α-cyanoalkylation by C-C bond cleavage: new access to benzofuran-2(3H)-ones.

We describe the first one-pot construction of a benzofuran-2(3H)-one scaffold via a radical cascade reaction of para-quinone methides with azodiisobutyronitrile and water. In the presence of CuI (20 mol%), this cascade proceeds smoothly through 1,6-conjugate addition/aromatization, α-cyanoalkylation by unstrained and non-polar C(aryl)-C(t-butyl) bond cleavage, and downstream cyano-insertion/cyclization/hydrolysis, which leads to cyano-containing benzofuran-2(3H)-ones with an excellent functional-group compatibility.