Abstract: The decomposition of dibenzosemibullvalene 1-carboxaldehyde tosylhydrazone (7a) and its ad, analog (7b) with several bases was examined under a variety of conditions. In each case, only 3, 4-benzofluorene (8) and terminal allene 9 were produced and the ratio of these hydrocarbons was consistently found to be approximately 2: 1, Decomposition of 7b under aprotic conditions gave rise to 8 containing deuterium only at the methylene ...