Abstract:. The two carbocyclic aromatic carbenes, 4-9-methano [1 l] annulenylidene (1) and 3, 8-methano [1 I Iannulenylidene (2), have been generated by decomposition of the corresponding ketone tosylhydrazone salts and the sodium salts of the tosylhydrazones of 3- and 2-formyl-I, 6-methano [IOIannulene (5 and 14). The latter reactions are believed to involve carbenecarbene rearrangements which proceed with a high degree of ...