γ-selectivity in the ceric ammonium nitrate promoted oxidative addition of silyl dienol ethers to silyl enol ethers

Trimethylsilyl dienol ethers are easily oxidized by ceric ammonium nitrate to give α-carbonylallyl radicals which are able to add to enolic carbon-carbon double bonds with very high γ regioselectivity, allowing the method to be applied to the synthesis of 6-oxo-α,β-unsaturated carbonyl compounds.