Quadricyclyl system

In a different biscyclopropylcarbinyl system encompassing a five-membered ring, the quadricyclyl system (100), the effect of the second cyclopropane ring is not so pronounced The relative rates given are for ) -naphthalenesulfonate (0) NS) acetolysis at 25 °C. Richey and Buckley have suggested as an explanation that the... 

Nortricyclyl and Quadricyclyl Systems.—The studies of the kinetics of acid-catalysed hydration of exo- and endo-norbornen-2-ols, referred to above, have been extended to include 3-nortricyclanol, 1-methyl-cis- and -rra s-3-nortricyclanols, and 3-methyl-3-nortricyclanol. Solvent deuterium-isotope effects are interpreted in favour of an A-S 2 hydration of the three-membered carbon ring of the secondary alcohols, or an A-1 mechanism for the tertiary alcohol in which case the rate-determining step is the formation of a carbocation (probably the 3-methyl-3-nortricyclyl cation) by elimination of water. 

Solvolysis of the triflate ester of quadricyclyl-7-carbinol (126) in trifluoroethanol containing triethylamine gave (127 80%) and four minor products. Clearly a cyclo-propylethyl carbonium ion rearrangement is involved rather than a direct 1,2-shift to give the quadricyclyl-octyl system (128). ... 

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