OZONOLYSIS OF 2-ACETYL-3,3-DIMETHYLNORBOR N-5-ENE AND SYNTHESIS OF A NEW, TRICYCLIC KETAL WITH A PATCHOULI LIKE ODOR - SYNTHESES IN THE ISOCAMPHANE SERIES .38.

The ozonolysis of endo-2-acetyl-3,3-dimethylbicyclo[2.2.1]hept-5-ene ( endo-1) and its exo-epimer(exo-1) is described. The reaction products, after reductive work up as well as after oxidative work up, are chara cterized. The first procedure furnished the corresponding cyclopentane derivatives in good yield, namely -dimethyl-2-(1-hydroxyethyl)-3,5-bi s-hydroxymethyl cyclopentane (2) as a cristalline compound from endo-1 , the epimeric 10 as an oil from exo-1. The oxidative work up furnishe d in both cases via keto-enol-tautomerism the same acid, 4-acetyl-5,5- dimethyl-1,3-cyclopentane dicarboxylic acid, characterized as its meth yl ester. Selective oxidation of the secondary hydroxyl group in 2 lea d to the novel, tricyclic, even acid stable ketal 17, with very intere sting olfactory properties.