Claisen rearrangement of an allyl phenyl ether with substituent groups in both ortho positions leads to the formation of a para-substituted product. Propose a mechanism for the following rearrangement.

Question: Explain the mechanism for the Claisen rearrangement of an allyl phenyl ether with substituent groups in both ortho positions, leading to the formation of a para-substituted product. Answer: The Claisen rearrangement of an allyl phenyl ether with substituent groups in both ortho positions involves a [3,3]-sigmatropic rearrangement. The mechanism starts with the shift of π electrons between the allyl and phenyl group to form a new bond between the terminal allyl carbon atom and the ether O-atom, resulting in a bicyclic transition state. Next, the new C-O bond breaks to form a new π bond between the terminal carbon of the allyl group and the ether carbon, while the π bond between the phenyl and ether carbon shifts back to form a C-O bond, completing the rearrangement to form a para-substituted, γ,δ-unsaturated carbonyl compound.