Bicyclo nonatriene, preparation

In summary, the parent 1,3-bishomotropylium ion [43] is produced upon protonation of the bicyclo[6.1.0]nonatriene [44] and its NMR spectrum was recorded under stable ion conditions. Two different bridged 1,4-bishomo-tropylium ion skeletons [45] and [46] have been prepared from a multitude of different precursors. However, no unbridged 1,4-system has yet been characterized. 

The bicyclo[4.2.1]nonatriene 323 was prepared by the [6+2] cycloaddition of internal alkyne with the complex 322 under irradiation [79]. Ligand exchange of 323 with toluene liberated 324. The complex 325 underwent the [6+2] cycloaddition with two moles of terminal alkyne to give the tetracyclic compound 327 via 326. The [6+2] cycloaddition of the complex 322 and 1,7-octadiyne (328) afforded 329 as a primary product, which was converted further to 330 in 56% yield by further intramolecular [6+2] cycloaddition [80]. The tropone complex 331 underwent intramolecular [6+2] cycloaddition under irradiation to give the strained tricyclic compound 332 in moderate yield [81]. 

All-ezs cyclononatetraenide salts have usually been made from bicyclo[6.1.0]nonatriene derivatives, the latter in turn having been got by carbene addition reactions to cyclooctatetraene. Thus the first preparations were as follows [52,60,61,66] ... 

Sodium cyclononatetraenide was also prepared, in lower yield, by proton extraction from bicyclo[6.1.O]nonatriene with the methyl-sulphinyl carbanion in dimethyl sulphoxide [66],... 

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