Regiochemical Control in Intramolecular Cyclization of Methylene-Interrupted Epoxydiols
作者:Radha S. Narayan、Meenakshi Sivakumar、Ezzeddine Bouhlel、Babak Borhan
DOI:10.1021/ol016118h
日期:2001.8.9
regiochemical routes for cyclization. The 5-exo process is the most prevalent under acidic conditions. However, the regioselectivity can be controlled by the appropriate choice of acid promoter and pendant groups adjacent to the epoxide. The 5-exo product is obtained exclusively without the presence of a carbocation-stabilizing pendant group. Alkenyl and thiophenyl groups adjacent to the epoxide alter the regioselectivity
[反应:见正文]亚甲基间断的环氧二醇具有多种环化途径用于环化。5-exo过程在酸性条件下最为普遍。然而,区域选择性可以通过相邻于环氧化物的酸的启动子和侧基的合适的选择来控制。仅在不存在碳阳离子稳定侧基的情况下获得5-exo产品。与环氧化物相邻的烯基和硫代苯基会改变区域选择性,并能够获得5-内四氢呋喃和6-内四氢吡喃产物。