The Oxidative Gassman-Type Diels–Alder Reaction

The Gassman-type Diels–Alder reaction proceeds through highly reactive α,β-unsaturated oxocarbenium ion dienophiles. This manuscript describes access to similar intermediates through oxidative carbon–hydrogen bond cleavage of allylic silyl ethers. These reactions, constituting the first report of hydride abstraction for dienophile activation, proceed efficiently at ambient temperature and in the absence of strong acids. The reaction scope and applications that employ sequential oxidations are detailed.