[2.2]NAPHTHALENOPHANES FROM INTERMOLECULAR [2+2] PHOTOCYCLOADDITIONS OF DIVINYLNAPHTHALENES

syn-[2.2]Naphthalenophanes were obtained exclusively in reasonable yields from the intermolecular [2 + 2] photocycloadditions of divinylnaphthalenes. The position of the vinyl group and the type of vinyl substituent affected the isomer ratio of the products. The structures of naphthalenophanes were elucidated by H-1-NMR spectroscopy including COSY and NOESY experiments. Among the divinylnaphthalenes examined, 1,4-, 1,5-, and 1,6-ones did not give the desired naphthalenophanes. By taking advantage of the effect of the substituents on the photoreaction, we could obtain [2.2]-(1,5)naphthalenophane derivatives from 1,5-bis(beta-carbethoxyethenyl)naphthalene and 1,5-bis(beta-phenylethenyl)naphthalene, but we could not obtain the 1,4-isomers, probably because they are highly strained. Although a mixture of two different divinylnaphthalenes was irradiated, only homo-adducts were obtained; no cross adducts were detected.