Conformational analysis of stereoselective epoxidations in flexible systems

Ducrot, Pierre; Bucourt, R.; Thal, C.; Marcot, Bernard; Mayrargue, J.; Moskowitz, H.

doi:10.1016/0040-4020(96)00320-1

Cited by 4 publications

(1 citation statement)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Over forty years ago, Corey and Sneen postulated that electrophilic attack on cyclohexenes occurs from an axial direction . Furthermore, Toromanoff has analyzed torsional angle changes that occur for a variety of related reactions, Vedejs et al have investigated the significance of torsional effects and preference for axial attack in the epoxidations of 4- tert -butylmethylenecyclohexane, and Ducrot and co-workers showed the same preference for axial attack exists in the stereoselective alkene epoxidations observed for flexible polycyclic systems. We have demonstrated how preferences such as this may be understood in terms of torsional effects in the transition state .…”

Section: Introductionmentioning

confidence: 99%

Torsional Control of Epoxidation Stereoselectivity in 1,2-Dihydronaphthalenes. Transition State Modeling with Semiempirical Quantum Mechanics

Lucero

Houk

1998

J. Org. Chem.

View full text Add to dashboard Cite

Recently, highly diastereoselective epoxidations of chiral 1,2-dihydronaphthalenes were reported. Crystallographic characterization of the major product indicated that the selectivity cannot be attributed to long-range steric effects. We examined this system through ab initio and semiempirical quantum mechanical modeling. Corroborating experimental data, our investigations explain the apparent irrelevance of direct interactions with substituents and address the insensitivity of the stereoselectivity to oxidant structure. Furthermore, extension of this model to other related epoxidation reactions indicates that pi-facial discrimination may be interpreted as a result of a preference for a staggered asynchronous transition state, obtainable only through axial attack.

show abstract