Silacycle-Templated Intramolecular Diels–Alder Cyclizations for the Diastereoselective Construction of Complex Carbon Skeletons

The utility of the dioxasiline ring as a π-facial directing group in the intramolecular Diels–Alder cyclization is explored. An initial investigation of substrate scope demonstrates that the rigidity of this directing group delivers robust stereocontrol across a number of substrates, affording single diastereomers in moderate to good yields. A mechanistic investigation reveals that the reactive diene is formed through γ deprotonation followed by [1,5] hydride shifts.