Tricyclo undeca-2,4,7,9-tetraene

Several norcarene derivatives were shown to undergo dehydrogenation with ring opening to form the more extended % system of cycloheptatriene. Thus, irradiation of chloranil in the presence of tricyclo[4.4.1.016]undeca-3,8-diene (45) gave rise to bicyclo[4.4.1]undeca-l,3,6-8-tetraene (46), while the quinone was reduced to the corresponding hydroquinone [229, 230]. 

Dithia-8,10,11-triaza-tricyclo 5.3.1.0J,< undeca-lI,4,7,10-tetraen 10-Trifluormethyl- E9c, 843 (Cyclopentadien + Hetaren)... 

The homobullvalenone 39 was cleaved by mercury(II) bromide to give a good yield of tricyclo[4.3.2]undeca-2,4,8,10-tetraen-7-one (40)/ but rearranged to tricyclo[5.4.0.0 ]unde-ca-2,6,9-trien-8-one (42) on heating. The tricyclic ketone 42 was formed in better yield by silver(I) trifluoroacetate promoted cleavage of the dibromocarbene adduct 41 of bullvalene. Homobullvalenone was probably the initial product of this rearrangement too, but at the reaction temperature (100°C), this completely rearranged. ... 

Beside the slow and inefficient initiation, the most important drawback of this first generation Ru-based ROMP and PROMP catalysts was their ionic character, which makes them insoluble in the pure monomers. All polymerizations had to be conducted in solution with polar solvents, which slowed down the reaction even more due to catalyst and monomer dilution. The only monomers which can be photopolymerized in solution or very fast (within seconds) [13] in bulk, are the oxa-benzonorbornenes like 1,4-epoxy-1,4-dihydronaphthalene (M6, R=H, m.p. 55°C) and 4-methyl-l 1-oxa-tricyclo[6.2.1.0 ]undeca-2,4,6,9-tetraene (M7, R=CH3, b.p. 60°C at 0.7 mbar, nD =1.5651) Scheme 3. M6 and M7 are, unfortunately, quite expensive. 

Vogel E, Scholl T, Lex J et al (1982) Norcaradiene valence tautomer of a 1,6-Methanol[10] annulene Tricyclo[4.4.1.0 ]undeca-2,4,7,9-tetraene-ll,ll-dicarbonitrile. Angew Chem Int Ed Engl 21 869-870... 

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