Acid-catalyzed hydrolysis of bridged bi- and tricyclic compounds. XXXVIII-Kinetics and mechanisms of 1- and 3-nortricyclanols

The disappearance of 1- and 3-nortricyclanols (1-OH and 2-OH) in aqueous perchloric acid was followed by capillary GC at different temperatures and acid concentrations. 1-OH is ca 1000 times more reactive than 2-OH. The activation parameters, solvent deuterium isotope effects and parameters of excess acidity equations were measured and the products were studied. Both isomeric nortricyclanols react according to the Ad(E)2 mechanism, i.e. the cyclopropane ring is protonated at the rate-determining stage of the reaction. The protonation causes, in the case of 1-OH, an isomerization called homoketonization with 2-norbornanone as the only product and, in the case of 2-OH, hydration, i.e. the formation of hydroxyl-substituted norbornyl cations, the fast attack of which by water produces several norbornanediols. Copyright (C) 2001 John Wiley & Sons, Ltd.