Carbocycle indane

We no longer have need of the enthalpy of formation of CH3-X-Y-Z-CH3. Again starting with the carbocyclic indane (X = Y = Z = CH2) (XfV) ... 

Intramolecular dehydrofluorination can be used to obtain some carbocyclic compounds. For example, the fluorinated compounds 4 and 6, on dehydrofluorination, are converted into the fluorinated derivatives of indan 5 and fluorene 7.121 22... 

We will take a semiempirical approach using numerous molecules, models, assumptions, and estimates rather than doing new calorimetric experiments and/or quantum chemical calculations. Indeed, we will also test what is probably the simplest assumption - that (4n + 2) n electrons found within a conjugated ring species is expected to result in enhanced stability and that this compound is called aromatic. We will consider the dihydroindene (indane) skeleton composed of a benzene ring fused to a nonaromatic five-membered ring that lacks additional double bonds, and will use this carbocyclic hydrocarbon with X = Y = Z = CH2 as a paradigm for many heterocyclic derivatives for which the possible aromaticity is of relevance to the current chapter. Similarly we use indene with -X-Y- = -CH=CH-, Z = CH2 for a variety of unsaturated heterocycles of interest here. 

Consider the dihydroindene (indane) (XIV) skeleton composed of a benzene ring fused to a nonaromatic five-membered ring that lacks additional double bonds. We may consider this carbocyclic hydrocarbon with X=Y=Z=CH2 (XV) as a paradigm for a... 

Returning now to the discussion of other carbocyclic species, we will consider the process involving 1-indanone and other keto derivatives of indane. We expect no special stabilization or destabilization over that of indane - none of these species may be expected to be aromatic or antiaromatic save that of the benzene ring therein. Starting with 1-indanone itself (X = CO, Y = Z = CH2) ... 

The intramolecular carbolithiation of carbon—carbon double bonds is an interesting route to functionalized carbocyclic and heterocyclic systems that has been developed in the past years and widely used in organic synthesis. In this context, aryllithiums have been described to carbometalate double bonds allowing the preparation of indanes,... 

Scheme4.22 Diastereoselective formation of indanes via rhodium-catalyzed tandem carbocyclization.

---