Electrostatic Effects on the Reactions of Cyclohexanone Oxocarbenium Ions

Nucleophilic substitution reactions of 4-substituted cyclohexanone acetals display different selectivities
depending upon the electronic nature of the substituent. Alkyl groups favor equatorial positions in the
oxocarbenium ions, but alkoxy groups prefer axial conformers. The reactions of acetals with alkoxy
groups constrained to either equatorial or axial positions suggest that the presence of an axial alkoxy
group distorts the oxocarbenium ion, changing its inherent preferences for facial attack.

4-取代环己酮缩酮的亲核取代反应，其选择性会随取代基的电子性质不同而呈现差异。烷基在氧鎓离子（oxocarbenium ions）中更倾向于占据平伏键位置，而烷氧基则偏好采用直立键构象。针对带有被约束于平伏键或直立键位置的烷氧基的缩酮所开展的反应研究表明，直立烷氧基的存在会使氧鎓离子发生构象扭曲，进而改变其固有的面进攻选择性偏好。