Die Herstellung von 3, 5-disubstituierten Cyclopentenen durch Ozonolyse von Norbornadien

The ozonization of norbornadiene is described. Oxidation of the intermediate with silver oxide furnishes 4-cyclopentene-cis-1, 3-dicarboxylic acid, reduction with sodium borohydride cis-1, 3-bis-hydroxymethylcyclopent-4-ene. The latter was converted to cis-3, 5-dimethylcyclopentene by reduction of the corresponding bis-tosylate with LiAlH₄. Hydrogenation of the ozonization intermediate over palladium-lead carbonate (Lindlar's catalyst) afforded 4-cyclopentene-cis-1, 3-dialdehyde. This reaction represents a new and selective method for the reduction of unsaturated ozonization intermediates.