Recent Chemistry of Bullvalene

The essential structural element of bullvalene is the homotropilidene system. Thus in any discussion of the chemistry of bullvalene, all bridged homotropilidenes must also be considered. The present article deals with new syntheses and with the thermal behavior of the homotropilidene system and of bullvalene. Emphasis is also placed on the syntheses and the NMR‐spectroscopic behavior of complexed bullvalene, of monosubstituted, disubstituted, and fused bullvalenes, and of some benzobullvalene derivatives.