75328-57-3Relevant academic research and scientific papers
Enhanced Solvolytic Reactivity of 1-Bromobicycloheptane: Intermediacy of a Stabilised Bridgehead Carbenium Ion
Della, Ernest W.,Pigou, Paul E.,Tsanaktsidis, John
, p. 833 - 834 (1987)
1-Bromobicycloheptane displays greater solvolytic reactivity than t-butyl bromide and produces a bridgehead carbenium ion which appears to be stabilised by transannular orbital interactions.
Bridgehead Carbocations: Solvolysis of a Series of 5-Substituted Bicycloheptyl Bromides. Nucleophilic Solvent Assistance to Ionization of 1-Bromobicycloheptane
Della, Ernest W.,Elsey, Gordon M.
, p. 967 - 986 (2007/10/02)
The synthesis of a range of 5-substituted bicycloheptyl bromides for solvolytic studies is described.It is found that the substituent has a profound effect on the rate of solvolysis of the system and acts principally in accordance with the magnitude of its inductive/field constant ?I.The most spectacular example of the effect of the substituent is provided by the COOMe group which leads to a retardation in the rate of methanolysis by a factor of 6.5E5.While a linear relationship in the plot of log k and ?I is generally obeyed, as expected for a mechanism mediated by the bicycloheptyl bridgehead cation, two of the bromides, 1-bromobicycloheptane and its 5-methoxy derivative, show deviant behaviour and react more rapidly than predicted on the basis of the Hammett plot.Evidence is presented to show that the enhanced rate of the parent is the result of nucleophilic assistance by the solvent.Anchimeric assistance in the solvolysis of 5-methoxybicycloheptyl bromide is attributed to the powerful p-donor property of the methoxy substituent which stabilizes the transition state in a unique concerted ring-opening and ionization step.
THROUGH-SPACE EFFECTS OF SUBSTITUENTS ON THE STABILITY OF THE 1-BICYCLOHEPTYL CATION.
Della, Ernest W.,Elsey, Gordon M.
, p. 1299 - 1302 (2007/10/02)
γ-Substituents are shown to have a dramatic effect on the stabilisation of the cationic transition state for solvolysis of 5-substituted bicycloheptyl bromides.
