Straightforward Construction of Fused 6,7,5-Tricarbocyclic Systems by Tandem [5 + 2]/[4 + 2] Cycloadditions.
One-pot coupling of an intramolecular thermal [5C + 2C] pyrone-alkene cycloaddition to a [4C + 2C] Diels-Alder reaction provides immediate access to 6,7,5-tricarbocyclic systems bearing a 1,4-oxa-bridge in the seven-membered carbocycle. The transformation entails the net formation of four carbon-carbon bonds and creates three new cycles and a minimum of five new stereocenters. Preliminary attempts to open the oxa-bridge by reaction of the adducts with samarium diiodide and trimethylsilyl triflate led to relatively unexpected deoxygenated and aromatized products.
Ramón Rodríguez
J.
J
Departamento de Química Orgánica y Unidad Asociada al CSIC, Universidad de Santiago de Compostela, 15706 Santiago de Compostela, Spain.
Rumbo
Antonio
A
Castedo
Luis
L
Mascareñas
José L.
JL