Bridged and Fused Rings

003 A the former is. 04 A shorter, and the latter 0.01 A longer, than the bonds in cyclopropane. The non-bonded interactions associated with the shorter bonds are much less than those between two eclipsed CH2 groups.  

Bicyclo[2,l,l]hexane (36) has been the subject of two studies. In the first it was assumed that the bonds of the cyclobutane ring are 0.01 A longer than the other bonds values of 1.547 and 1,537 A were obtained, with a 

From studies of anti- and 5 n-tricyclo[4,2,0,0 ]octane (40), it has been concluded that in both molecules all the cyclobutane rings are only slightly puckered with 9 3° presumably the multiple bridging reduces the 

In bicyclo[2,2,l]heptane, norbomane (43), the cyclohexane ring is locked in the boat form by a bridge. This molecule, which also has static 

Configurationally, bicyclo[2,2,l]hepta-2,5-diene, norbomadiene (44), resembles norbomane. However, the six-membered ring fragment, cyclo-hexa-1,4-diene, is not locked in an unfavourable form, but is simply folded more than in the free ring. The results of the several recent investigations 

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Tyrrell, E., Skinner, G. A., Bashir, T. The synthesis of bridged and fused ring carbocycles using a novel variation of an intramolecular... 

There is no settled convention for the representation of polyacetals and other complex cyclic derivatives of carbohydrates. To facilitate the comparison of polycyclic derivatives of carbohydrates with alicyclic compounds, the carbohydrate derivatives will be drawn in perspective, with single rings and fused rings placed in the plane of the paper, and with darkened or broken lines used to show the orientation of substituents and bridges above or below the plane of the rings, respectively, as is customary for terpenes and steroids. 

Intramolecular reactions between donor and acceptor centres in fused ring systems provide a general route to bridged polycyclic systems. The cts-decalone mesylate given below contains two d -centres adjacent to the carbonyl function and one a -centre. Treatment of this compound with base leads to reversible enolate formation, and the C-3 carbanion substitutes the mesylate on C-7 (J. Gauthier, 1967 A. Belanger, 1968). 

Buckminster Fuller was the inventor of self-supporting polygon frameworks, e.g., of pavilions. Synonyms (root)ballene, buckminsterfullerenc( BF ), carbosoccer, soo r(ball)ene, spherene. The proposed bridged-fused ring system and von-Baeyer names and numberings vary. 

The compounds of this series of fused (5 5 5) systems of three five-membered rings so far encountered may logically be divided into the following three distinct classes (1) linearly fused (5 5 5) systems, (2) angularly fused (5 5 5) systems, and (3) spiro-fused (5 5 5) systems. In addition to these three distinct classes, there are other compounds reported bearing bridged and propellane moities which are classified under the heading miscellaneous . 

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