75004-14-7Relevant academic research and scientific papers
Ouverture acidocatalysee d'epoxydes bicyclooctaniques: Intervention d'un mecanisme A2 avec retention de configuration
Plenat, Francoise,Renard, Gilbert,Christol, Henri
, p. 125 - 132 (2007/10/02)
During the stereochemical study of the products obtained by acid-catalysed ring opening of 2,3-endo epoxynorbornane, a concerted "front" attack mechanism has been brought to light.This can be explained by the known preference for intramolecular rather than intermolecular mechanisms.This acid-catalyzed ring opening has been extended to 2,3-epoxybicyclooctane, the bonds of which are in the same spatial position towards the epoxy carbon atoms and which can undergo anti and "front" attack of the epoxide ring.Products arising from both kinds of intramolecular attack can be isolated.In addition, the ring opening reaction of 2,3-endo and exo epoxy-5,6-trans-dicarbomethoxybicyclooctanes indicates that they proceed by a concerted mechanism, so that the "front" attack mechanism must be specially favourable to these bicyclic structures.Since the reactions considered are like bimolecular nucleophilic substitutions, for which the anti attack mechanism is known to be energetically favoured over the "front" attack, the following suggestions can be made to explain our results: there is steric hindrance to anti approach of the external nucleophile, torsional strain lowering and favourable orbital alignment for the "front" attack.
