Oxepinobenzofurans—The True Nature of Sterically Hindered “Benzoxetes”

The compounds hitherto regarded as benzoxetes (1) have proved to be oxepins (2). Structure (3) was ruled out by X-ray structure analysis of (2), R1=tBu, R2R4Cl, R3OMe. This result appears particularly important with regard to oxidative coupling of phenols (biogenesis of phenolic natural products).