Acid‐catalyzed hydrolysis of bridged bi‐ and tricyclic compounds. XXXIX—Kinetics and mechanisms of the hydration reactions of 1‐ and 3‐acetylnortricyclanes

Abstract

The disappearance of 1‐ and 3‐acetylnortricyclanes (1‐Ac and 2‐Ac) in aqueous perchloric acid was followed by capillary gas chromatography at different temperatures and acid concentrations. 1‐Ac is much less reactive than 2‐Ac. The activation parameters, solvent deuterium isotope effects and parameters of excess acidity equations were measured and the products studied. 1‐Acetylnortricyclane is hydrated according to the A‐2 mechanism, i.e. the carbonyl oxygen is protonated in the fast pre‐equilibrium and one water molecule attacks at the rate‐limiting stage the partially open cyclopropane ring, producing 6‐acetyl‐2‐norborneols. 3‐Acetylnortricyclane is hydrated according to the AdE2 mechanism, i.e. the cyclopropane ring is slowly protonated and opened, with subsequent fast attack of water producing 3‐, 5‐ and 7‐acetyl‐2‐norborneols. Copyright © 2002 John Wiley & Sons, Ltd.