Saturated bicyclo heptanes

In general, excellent diastercoselectivities are observed in the catalytic hydrogenation of bicyclic systems. Bicyclo[2.2.1]heptenes, such as 1, are hydrogenated to the corresponding saturated bicyclo[2.2.1]heptanes yielding nearly exclusively the ewfo-c/.y-product, independent of the catalyst, the reaction conditions and the solvent53- 54. 

Bicyclo[4.2.0]octan-7-ones 7, substituted at C8, resulted from addition of 7-lithio-7-methoxy-bicyclo[4.1.0]heptane to saturated and unsaturated aldehydes and subsequent rearrangement.146148... 

Rule 1. Use the name norbomane for the fundamental saturated ring system, which is bicyclo[]2.2.1]] heptane. Use the name bornane for the saturated larger parent compound, which is 1,7,7-trimethylbicyclo[]2.2.1]] heptane. Form a series of names based on these two new terpene names. 

Under similar conditions, the 2-methylenebicyclo[2.2.1]heptane, or norcamphene (7) was conYerted to the isomer 6, through the intermediate formation of 5, whose maximum concentration in the mixtures is about 10%. This slow reaction is complicated by extensive hydrogen transfer and polymerization reactions (20), leading to saturated bicyclic hydrocarbons 2-methylbicyclo[2.2.1]heptane (12), bicyclo[3.2.1]- and [3.3.0]octanes (15 and 17). Isomerization of norcamphene (7) to hydrocarbons of the bicyclo[2.2.1]heptane series is also noticed at 250° in the vapor phase, but this is the main reaction at 140° in the liquid phase with the same catalyst. The main products are then 2-methyl-bicyclo[2.2.1]-2-heptene (8), l-methylbicydo[2.2.1]-2-heptene (10), and l-methyltricyclo[2.2.1.0]heptane 11 (13). The tricyclic isomer has been observed in the liquid-phase silica-alumina-catalyzed conversion of norbornene (21). 

Similar results of metal-mediated cyclopropane ring opening have been obtained with saturated polycyclic hydrocarbons containing cyclopropane subunits. Prominent examples are bicyclopropyl (I) and similar systems such as quadricyclane (2 tetracyclo[3.2.0.0 . 0 ]-heptane), tetracyclo[3.3.I.0. 0 ]nonane (3), bicyclo[1.1.0]butane (4) and other bicyclo[n.l.O]alkanes 5, spiropentane (6) and other spirocyclopropanecycloalkanes 7. ... 

Like protons, transition-metal ions are strongly acidic and they can, in principle, add to both the C—H and C—C bonds of alkanes. As already noted in the section on proton affinities (Table 1) strained cycloalkanes are intrinsically more basic than open-chain alkanes, and the reaction of cyclopropane with Pt((II) to form a platinacyclo-butane (equation 14) was the first reaction of a formally saturated hydrocarbon with a transition-metal ion . The driving force in this reaction is relief of the strain associated with the small ring. The resulting metallacyclobutane is essentially free of ring strain. Many low-valent transition-metal complexes have been found to react with cycloalkanes. Metal ions convet the strained hydrocarbons quadricyclane , cubane , bicyclo-[2.1.0]pentanes , bicyclo[3.1.0]hexanes , bicyclo[4.1.0]heptanes and bicyclo-butanes into less strained isomers (usually cyclohexanes). 

FIGURE 2.16 Examples of saturated bicyclic compounds (a) bicyclo[3.3.0]octane, (b) bicyclo[4.3.0]nonane (hydrindane), (c) bicyclo[4.4.0]decane (decalin), (d) bicyclo[2.2.1]heptane (norbornene), and (e) bicyclo[2.2.2]octane). 

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