Regioselective thermal cage-opening reactions of 4-amino substituted 1,3-bishomocubanones

Thermolysis of 4-substituted 1,3-bishomocubanones is strongly dependent on the electronic nature of the bridgehead substituent. 4-(N-benzyl)amido-substituted cage compounds 12 unexpectedly furnish bicyclic annelated cyclopentenones 13, whereas the 4-acetoxy-1,3-bishomocubanone is thermally stable up to 750°C. The free benzylamine 16 undergoes cage opening even at room temperature to give tetracyclic dione 17.