Formation of Homologous Bird-Cage Molecules. Strain ans Transannular Effects

Article abstract of DOI:10.1021/jo01300a026

The three endo-endo dienes 3 (n = 1-3) were prepared by Diels-Alder reaction of 1,2,3,4,7,7-hexachloronorborna-1,5-diene with the cyclic dienes 2 (n = 1-3).The reactivity of the dienes 3 in forming the cage compounds 4 under the influence of bromine or UV light decreased with n from 1 to 3.The same effect of n on reactivity was shown in formation of the half-cage ketones 7 (n = 1-3) from the epoxides 6 (n = 1-3) and of the cage alcohols 9 (n = 1-3) from the ketones 7 (n = 1-3).An explanation based on the effect of n on the difference in strain energy of products and reactants is advanced.