Bicyclo deca-2,4,6,9-tetraene

The skeletal rearrangement of various strained cyclic compounds is carried out with a catalytic amount of soluble complexes of PdCl2. Namely, the rearrangements of bulvalene (67) to bicyclo[4.2.2]deca-2,4,7,9-tetraene (68)[54], cubane (69) to cuneane (70)[55], hexamethyl Dewar benzene (71) to hexa-methylbenzene (72)[56], and 3-oxaquadricyclanes[57] and quadricyclane (73) to norbornadiene[58-60] take place mostly at room temperature. Reaction of iodocubane (74) with a terminal alkyne catalyzed by Pd(0) and CuBr unexpectedly affords an alkynylcyclooctatetraene 75, without giving the desired cubylalkyne 76. Probably the rearrangement is a Pd-catalyzed reaction[61]. 

The cobalt(I)-catalysed 6 + 2-cycloadditions of cyclooctatetraene with monosubsti-tuted alkynes produced monosubstituted bicyclo[4.2.2]deca-2,4,7,8-tetraenes in good yields.185 The 6 + 3-cycloaddition of fulvenes (145) with 3-oxidopyrylium betaines (144) formed 5-8 fused oxa-bridged cyclooctanoids (146,147), which can be manipulated by cycloaddition reactions to produce key intermediates (148,149) for the synthesis of fused cyclooctanoid natural products e.g. lancifodilactones (Scheme 38).186,187... 

Skeletal rearrangements are rare, but are found for strained bi- and polycyclic alkenes, e.g., bullvalene , bicyclo[4.2.2]deca-2,4,7,9-tetraene , 4,5-exo-trimethylene-2-norbornene , 6-methylenebicyclo[3.1.1]heptane ", 5-methylbicyclo[2.1.1] hexene N-benzyl-9-aza-bicyclo[4.2.2]deca-2,4,7-triene , dibenzobicyclo[2.2.2]-octatriene derivatives and bornylene ... 

Tricyclo[6.2.0.0 ]deca-1 A7.9-tetraene to Bicyclo[6.2.0]-deca-1A5A9-pentaene... 

Tricyclo[6.2.0.0 °]deca-l,4,7,9-tetraene gives bicyclo[6.2.0]deca-l,3,5,7,9-pentaene in a first-order process at 100°C (Scheme 11.7). ... 

There are still plenty of mysteries in mass spectrometry, however. For example, the Jones research group first made the molecule bicyclo[4.2.2]deca-2,4,7,9-tetraene m = 130 Rg. 15.15) over 40 years ago, and were startled then to find that the base peak in the mass spectrum was at m/z = 115. It seemed likely that this ion m — 15) represented the loss of a methyl group from the parent ion. We... 

FIGURE 15.15 Bicyclo[422]deca-2,4,7,9-tetraene apparently loses a methyl group in the mass spectrometer. How ... 

The chemistry of ketone (674) and its derived compounds have been extensively reported, and includes examples of bicyclo[4,2,1 ]deca-2,4,7,9-tetraene rearrangements to 9,10-dihydronaphthalene valence isomers. Protic decomposition of the... 

E, Z,E,Z,Z-isomer suffers transannular H.H-repul-sion. Solution enthalpy of hydrogenation measurements are perhaps plausible to suggest, but catalyti-cally facilitated interconversion of E,Z,E,Z,Z-[10]-annulene into its valence isomer 4a,8a-dihydronaph-thalene (bicyclo[4.4.0]deca-2,4,7,9-tetraene) is also expected. In addition, the transannular effect in both the annulene and cyclodecane hydrogenation product... 

Skeletal rearrangements of some strained compounds, such as bulvalene to bicyclo[4.2.2]deca-2,4,7,9-tetraene, cubane to cuneane, hexamethyl Dewar benzene to hexamethylbenzene (eq 52), and quadricyclane to norbornadiene (eq 53), are catalyzed by derivatives of PdCl2. 

A further, but not preparatively significant, synthesis of the trione (259) and thus bullvalene (18) is described in Scheme 39. A series of substituted bicyclo-[4,2,2]deca-2,4,7,9-tetraenes is readily prepared from (260) (see Scheme 37). The earlier reports of additions to the parent tetraene are now supplemented by details of electrophilic additions to 7-substituted derivatives (Scheme 40). 

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