Carbenes in polycyclic systems. Generation and fate of pentacyclo[5.4.0.02,6.03,10.55,9]undecanylidene species

Pyrolysis of lithium or sodium salts of pentacyclo[5.4.0.02,6.03,5.05,9]undec-8,11-dione ditosylhydrazone 1 gave two products, 4,5-diazahexacyclo[6.4.1.02,7.03,11.06,10.09,12]tridec-4-ene 2 and tetracyclo[6.3.0.04.11.05,9]undeca-2,6-diene 3 in a 9:1 ratio. Azoalkane 2 proved to be extremely thermally and photochemically stable. This result supports the proposed mechanism of formation of 3, which includes the generation of dicarbene species 6a.