Investigations into the Palladium and Rhodium Catalyzed Ring Opening Reactions of C1-Substituted Oxabicyclic Alkenes.

Optimized conditions for rhodium and palladium catalyzed ring opening reactions of C1-substituted oxabicyclic alkenes using aryl boronic acid and aryl iodide nucleophiles was developed. The effect of substitution on the aryl nucleophile as well as the effect of C1 substitution on the oxabicyclic alkenes was also studied. Nucleophiles carrying electron-donating substituents provided the ring opened products in excellent yields regardless of the position, while electron withdrawing substituents were more susceptible to steric interactions. Although two different regioisomers are possible, all reactions were found to be highly regioselective, providing single regioisomers in each case. When under palladium catalysis, ring opened products containing electron withdrawing groups rapidly underwent base catalyzed dehydration into the corresponding naphthalene derivatives. For each study a new mechanism was also proposed based on our findings.