Investigation of dynamic effects on the product selectivity in the acid catalyzed rearrangement of epoxides to carbonyl compounds

The mechanism of epoxides rearrangement in solution has been studied for more than 70 years now. In early stages of this research it was suggested by Winstein and Hederson that the course of the rearrangement depended on just two factors: the migratory aptitude of the substituent groups and the direction of the ring opening. Traditionally, these migrations favor the formation of the most stable carbenium ion. The obtained observations led them two propose two possible mechanisms: a one-stage concerted process and a two-stage mechanism. Reported mechanistic details on the literature do not  are still in need of being studied.

It is our goal to study the mechanism of the acid catalyzed rearrangement of epoxides in order to evaluate the influence dynamic effects have on the product selectivity.This type of phenomena could actually explain the selectivity of some natural product biosynthetic routes.

Our results of  gas phase DFT calculations at the B3LYP /6-31G* level of theory suggest there is a transition state connecting the two possible products, opening the possibility for dynamics to play a role in the product selectivity. The typical experimental conditions will involve the use substituted epoxides and protic acids in non nucleophilic solvents. The instrumental technique will be 1H NMR for the determination of the product ratio. The theoretical methods will include gas phase and solvent model DFT (B3LYP)/6-31G* calculations as well as classic trajectory studies.