Quadricyclane tricyclo- heptane

Nortricyclanylidene (tricyclo[2.2.1.02,6]heptan-3-ylidene, 46) was originally generated via the Bamford-Stevens reaction of the corresponding 3-nortricyclanone p-tosylhydrazone sodium salt (49) (Scheme 9).126 The formation of quadricyclane (tetracyclo[2.2.1.02 6.03 5]heptane, 48) was anticipated, from an intramolecular... 

Of the photochemical conversions of 3,6-bridged cyclohexa-1,4-dienes to 3,6-bridged syn-tricyclo[3.1.0.0 ]hexanes, the light-induced isomerization of norbornadienes to quadricyclanes (see Houben-Weyl, Vol.4/5a, pp 232-237) has been most intensively studied. The parent hydrocarbon, quadricyclane (1, tetracyclo[3.2.0.0 . 0 ]heptane) has become available on a preparative scale by acetophenone sensitized isomerization of norbornadiene (bicyclo [2.2.1]hepta-2,5-diene). ... 

Hogeveen and Volger (8) observed that 1,5-cyclooctadienedichloro-palladium and iy -allylchloropalladium dimer were active catalysts for the conversion of quadricyclane (2) to norbornadiene (l). Furthermore, Dauben and Kielbania (9) have found that [(CeH5)3P]2l dCl2 effects the conversion of tricyclo-[4,l,0,0 ]-heptane into 3-methylenecyclohexene. 

Metal-catalysed Isomerizations Because of the wide range of values previously available, Wiberg and Cannon have accurately determined the enthalpy of the quadricyclane- norbornadiene conversion as —26.16 0.24kcal.mol in solution and —27.13 0.24 kcal mol" in the gas phase by studying the metal-catalysed rearrangement. The same authors have studied the metal-catalysed tricyclo[4,1,0,0 ]-heptane- 3-methylenecyclohexene reaction [A/T/soIution) = — 29.99 0.08 kcal mol" cf. 25.8 kcal mol" for bicyclobutane butadiene)]. 

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