Effects of Bridgehead Substitution on Structure and Reactivity of the 7-Norbornyl Cation (CROSBI ID 201663)
Prilog u časopisu | izvorni znanstveni rad | međunarodna recenzija
Podaci o odgovornosti
Sunko, Dionis E. ; Vančik, Hrvoj ; Mihalić, Zlatko ; Shiner, V.J.Jr. ; Wiglis, F.Pz.
engleski
Effects of Bridgehead Substitution on Structure and Reactivity of the 7-Norbornyl Cation
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.
7-norbornyl cation ; solvolysis ; neigboring group participation
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Podaci o izdanju
59 (23)
1994.
7051-7055
objavljeno
0022-3263
1520-6904
10.1021/jo00102a033