Intramolecular [2+2] Photocycloaddition. 5. Synthetic Methods toward [2.n]-, [3.n]-, and [4.n]Naphthalenophane Skeletons by Using α,ω-Bis(vinylnaphthyl)alkanes

Abstract [2+2] Photocycloaddition, cationic cyclocodimerization, and reductive ring enlargement were developed for the syntheses of [2.n]-, [3.n]-, and [4.n]naphthalenophanes, respectively, from α,ω-bis(vinylnaphthyl)alkanes as a single starting material. Using the exclusive syn selectivity of the former two methods, the room required for the intraannular naphthalene-ring rotation in the ring system is determined.