Transition States of Epoxidations: Diradical Character, Spiro Geometries, Transition State Flexibility, and the Origins of Stereoselectivity

摘要

The transition structures for the epoxidations of ethylene by performic acid, dioxirane, oxaziridine, and peroxynitrous acid have been located with density functional theory methods using the Becke3LYP functional and 6-31G~* basis set. All of the epoxidations have spiro transition states; those with performic acid and dioxirane are early and involve synchronous oxygen transfer, while those with oxaziridine and peroxynitrous acids are later with asynchronous oxygen transfer.