An Arylative Ring Expansion Cascade of Fused Cyclobutenes via Short-Lived Intermediates with Planar Chirality.

An arylative ring expansion cascade has been developed for the synthesis of medium-sized carbocycles from fused cyclobutenes. This reaction proceeds through a short-lived cis,trans-cycloalkadiene intermediate that is formed by thermal 4π electrocyclic ring opening. Chirality transfer experiments provide direct evidence for the transient generation of the intermediate.