Intramolecular [2+2] photocycloaddition of a dimeric vinylpyridine 1 through a singlet-excited species efficiently formed the corresponding syn- and anti-pyridinophanes 2 and 3. The syn-isomers were elucidated spectroscopically and by X-ray crystallography as exo,syn-configured. The high selectivity under formation of exo,syn-2 was thoroughly investigated. Consequently, an exo-outstretching effect, which is