Naslov
Effects of Bridgehead Substitution on Structure and Reactivity of the 7-Norbornyl Cation

Autori
Sunko, Dionis E. ; Vančik, Hrvoj ; Mihalić, Zlatko ; Shiner, V.J.Jr. ; Wiglis, F.Pz.

Izvornik
Journal of organic chemistry (0022-3263) 59 (1994), 23; 7051-7055

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
7-norbornyl cation ; solvolysis ; neigboring group participation

Sažetak
A systematic investigation was undertaken of the effect of bridgehead substitution on the solvolytic reactivity of 7-norbornyl triflates in aqueous TFE. Methyl substitution increases the rate 60-fold and the effect of multiple substitution is additive. Chlorine, on the other hand, exhibits a combined inductive and resonance effect and decreases the reactivity 1700 times. The observed normal secondary P-deuterium isotope effect of the 1, 4-d(2) derivative can be rationalized by assuming a tilted C-s geometry for the cationic transition structure which is only slightly higher in energy than the nonclassical intermediate cation of C-1 symmetry. Bridgehead methyl-d(3) kinetic isotope effects are similar to those associated with the nonmigrating methyl group in neopentyl ester solvolyses. These results are in agreement with the recently published structure of the 7-norbornyl cation calculated at the highest ab initio level which has confirmed its nonclassical nature as originally proposed by Winstein.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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