Tetraquinanes via [4 + 4] photocycloaddition/transannular ring closure.

Intramolecular [4 + 4] photocycloaddition of a furan and a cyclopentane-annulated 2-pyridone yields a cyclooctadiene product with four new stereogenic centers. Transannular ring closure produces the 5-5-5-5 fused ring system of the crinipellins, including three contiguous quaternary carbons, with the correct absolute stereochemistry derived from (-)-carvone.