A New Route to Diastereomerically Pure Cyclopropanes Utilizing Stabilized Phosphorus Ylides and γ-Hydroxy Enones Derived from 1,2-Dioxines: Mechanistic Investigations and Scope of Reaction

摘要: A new chemical transformation for the construction of diversely functionalized cyclopropanes utilizing 1,2-dioxines and stabilized phosphorus ylides as key precursors is presented. Through a series mechanistic studies we have elucidated clear understanding hitherto unknown complex relationship between 1a−e, their isomeric cis/trans γ-hydroxy enones (23 21a−e), hemiacetals 24a−e, β-ketoepoxides (e.g., 26), how these can be utilized to construct cyclopropanes. Furthermore, several synthetically useful routes structural isomers are Key features cyclopropanation include ylide acting mild base inducing ring opening cis 23a−e, followed by Michael addition 23a−e attachment electrophilic pole hydroxyl moiety, affording intermediate 1-2λ5-oxa...