Maximum bridging ring

At this point, the student should be able to find the "strategic bonds", looking first for all the primary rings, the set of synthetically significant rings, the maximum bridging ring, etc., as explained in Chapter 7. 

Bridging sites s.s. ring with maximum bridging atoms,... 

In order to illustrate the difference between these concepts, Corey analyses structure 26 in terms of the number of bridgehead atoms, the number of times bridged and the number of bridging atoms (the rings with the maximum number are indicated with bold numbers)... 

As in the case of [njparacyclophanes the torsional barrier(s) as well as the distortion of the benzene rings (as reflected for example in optical properties) depend on the size of the bridges, i.e. on m and n Both reach their maximum if m = n = 2. Up to [3.4]paracyclophanecarboxylic acid (26) a separation into enantiomers could be accomplished 34137), whereas the [4.4] homologue is optically too labile for a resolution 37). 

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