Bicyclo dodecatrienes

Murakami and co-workers have shown that phenyl- and vinyl-substituted vinylallenes react in a palladium-catalyzed intermolecular [4+ 4]-cycloaddition in the presence of a palladium complex to give the cyclooctadiene cycloadducts in moderate to good yields (Scheme 29).103 In a method reported by Lee and Lee, bicyclo[6.4.0]-dodecatrienes are prepared in good overall yields via a two-step, one-flask procedure that involves a serial palladium-catalyzed cross-coupling/[4 + 4]-cycloaddition followed by [4 + 2]-cycloaddition (Scheme 30). Overall, this two-step process impressively brings together five simple components to form relatively complex bicyclic products.1... 

A bicyclo[6.2.2]dodecatriene instead of the condensed 8 6-fused ring system is formed by a fluoride ion-triggered intramolecular alkylation. Complexation with fluoride ion to render bis(allylsilanes) dramatically reactive is indicated. ... 

The observed K of cj/clohexene agreea best with that expected for a halfchair model non-planar arrangements specified for 1,3- and l,5-cyclooct Miiene3, for 1,5,9-cyclo-dodecatriene, and for bicyclo(2,2,l) heptadiene, give predicted K s in accord with experiment... 

Rh(I)-catalysed intramolecular 6 -I- 2-cycloaddition of alkyne-allenylcyclobutanes has been reported for the preparation of bicyclo[6.4.0]dodecatrienes (Scheme 155). ... 

More effort from others has expanded the types of substrates involved in the [5+2] cycloadditions. For example, Saito and Hanzawa et al. reported the rhodium-catalyzed [5+2] cycloaddition of ester-tethered aUcyne-VCPs using fluorinated alcohols as solvents (see (14)) [27]. Mukai s work demonstrated that aUcyne-allenylcyclopropanes can also undergo rhodium-catalyzed [5+2] cycloaddition to give bicyclo[5.4.0] undecatrienes or bicyclo[5.5.0]dodecatrienes (see (15)) [35]. In related work from Yu s group, they found that the aUcene-VCP with an internal cyclopropane with the c/s-substitution can react well by following the [5+2] pathway (see (16)) while the trans isomer underwent the [3+2] process (see [3+2] section and (32)) [36]. 

SCHEME 20.9 S)mtheses of bicyclo[5.4.0]undecatrienes and bicyclo[5.5.0]dodecatrienes. 

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