An Efficient Stereocontrolled Strategy in the Cyclopropanation Reactions of α,β-Unsaturated Ketones with Semistabilized Ylides: Highly Selective Synthesis of Two Geometrical Isomers of Vinyl-Substituted Cyclopropane Derivatives
作者:Yong Tang、Yao-Zeng Huang、Li-Xin Dai、Jie Sun、Wei Xia
DOI:10.1021/jo9610218
日期:1997.2.1
The semistabilized telluronium ylides 2a-e, generated in situ from the corresponding telluronium salts 1a-e, reacted with alpha,beta-unsaturated ketones 6a-d to afford cis-2-vinyl-trans-3-substituted cyclopropyl ketones with high stereoselectivity and in high to excellent yields. Conversely, these enones gave trans-2-vinyl-trans-3-substituted cyclopropyl ketones, when the corresponding arsonium ylides 10a-e were employed. Other factors such as solvent and amount of base also influenced the stereochemistry of this reaction. A mechanistic rationale is discussed briefly.