Ozonolysis of a series of 1-substituted indenes. The substituent steric effects on the ozonide exo/endo ratios

The ozonolysis of a series of disubstituted (1,2 and 1,3) and trisubstituted (1,2,3) indenes 1-28 in carbon tetrachloride at 20°C has been investigated. The major product in each case was the corresponding bicyclic ozonide, usually obtained as a mixture of exo and endo isomers, whose ratio varied markedly, but inconsistently, with the nature of the 1- and 2-substituents. Since the product stereochemistry was found to show little dependence on the relative isomer stability or the substituent electronic effects, the results have been discussed in terms of the direction of approach of the ozone to the indene substrate. © 1984 American Chemical Society.