Bicyclo undeca-2,4,7,10-tetraene

In contrast to 154 the isomeric bicyclo[4.4.1]undeca-3,5,8,10-tetraene-2,7-dione /bicyclic structure. Formation of the bis-Grignard reagent 163... 

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]. 

Goldstein and Kline (1973) have reported a CnH cation of unusual structure. Conventional low temperature FSO3H extraction of sj/ -bicyclo[4.3.2]-undeca-2,4,8,10-tetraen-7-ol [456] gave an ionic solution the H-nmr spectrum of which showed three bands (further structured by coupling). The... 

Evidence that the synthetic substance (5), bicyclo[4,4.1]undeca-3,5,8-IO-tetraene-2,7-dione, can be described as a quinone, is that treatment with zinc dust and acetic anhydride in the presence of pyridine leads readily to reductive acetylation that affords the aromatic 2,7-diacetoxy-l,6-methanol[IO]annulenc (6). ... 

We also know the enthalpies of formation of the triene, l,6-(butane-l,4-diyl)-tropilidene (bicyclo[4.4.1]undeca-l,3,5-triene, 88) as well as of the related tetraene [ 1,6-(2-butene-1,4-diyl)-tropilidene, 89] and pentaene [l,6-( 1,3-butadiene-1,4-diyl)-tropilidene, 90], respectively. Choosing Roth s suggested value for the enthalpy of formation of the parent tropilidene so that all four species are taken from the same primary source, we find that attachment of these varying 4-carbon chains increase the enthalpy of formation by —40, 74 and 136 kJ mol respectively. Upon affixing these same 4-carbon chains to benzene to form tetralin, 1,4-dihydronaphthalene and naphthalene (91, 92 and 7, respectively) the corresponding enthalpy of formation changes by —57, 51 and 68 kJmoU. ... 

In some cycloadditions of cycloproparenes, secondary products derived from opening of the cyclopropane bond were observed. The reaction of benzocyclopropene with buta-1,3-diene gave the expected bicyclo[4.4.1]undeca-l,3,5,8-tetraene(5)in 6% yield 2-vinyl-2,3-dihydro-17/-indene (43%) and 8,9-dihydro-5/7-benzocycloheptatriene (10%) were also obtained which are believed to arise via a competing radical pathway. ... 

Vinylspiro[2.6]nonatriene to Bicyclo[5.4.0] undeca-1,3,5/9-tetraene and Phenyl Analogues... 

However, the syn isomer rearranges to bicyclo[4.3.2]undeca-2,4,7,10-tetraene at only 60°C presumably via a 3,3-shift. The tetraene apparently undergoes an intramolecular Diels-Alder reaction to a polycyclic hydrocarbon which undergoes another 3,3-shift to give tetracyclo[5.4.0.0. 0" ]undeca-5,8-diene with log k = 13.65 - 28440/2.3/ r (Scheme 12.26). ... 

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