Pericyclic Reactions

Step 1: Analyze the reaction shown.
The reaction shows a 1,5-hydrogen or carbon shift accompanied by formation of a new sigma bond and movement of π-electrons. Such transformations are typical of sigmatropic rearrangements.
Step 2: Why not the other options?
(A) Oxy-Cope is specific to 1,5-diene systems with –OH; not applicable here.
(C) Claisen involves allyl vinyl ethers; not relevant here.
(D) All sigmatropic rearrangements fall under pericyclic reactions, but (B) is the more specific answer.
Step 3: Conclusion.
Therefore, the given conversion represents a sigmatropic rearrangement.

Step 1: Revisiting pericyclic reaction rules.
Woodward–Hoffmann rules determine whether cycloadditions are photochemically or thermally allowed.
[4 + 2 ] → thermally allowed (Diels–Alder).
[2 + 2 ] → photochemically allowed.
Step 2: Checking each statement.
(A) Incorrect → [4 + 2 ] occurs thermally, not photochemically.
(B) Correct → [2 + 2 ] is photochemically allowed.
(C) Correct → Diels–Alder is a classic thermally allowed reaction.
(D) Incorrect → Only s-cis dienes undergo Diels–Alder; transoid (s-trans) can’t cyclize.
Step 3: Conclusion.
Thus, the incorrect statements are (A) and (D).