Investigation of Mn(III)-Based Oxidative Free Radical Cyclization Reactions toward the Synthesis of Triptolide: The Effects of Lanthanide Triflates and Substituents on Stereoselectivity
作者:Dan Yang、Xiang-Yang Ye、Ming Xu、Kwan-Wah Pang、Kung-Kai Cheung
DOI:10.1021/ja993598n
日期:2000.3.1
Mn(III)-mediated oxidative free radical cyclization reactions are useful for construction of polycyclic compounds. In the total synthesis of triptolide (3) and its related compounds, construction of tricyclic skeletons 4 and 5 was achieved by the Mn(OAc)3-mediated oxidative radical cyclization of a series of acyclic precursors 6−9. The addition of a catalytic amount of lanthanide triflates was found
Mn(III) 介导的氧化自由基环化反应可用于构建多环化合物。在雷公藤内酯 (3) 及其相关化合物的全合成中,通过 Mn(OAc)3 介导的一系列无环前体 6-9 的氧化自由基环化,构建了三环骨架 4 和 5。发现添加催化量的镧系元素三氟甲磺酸盐可显着提高这些自由基环化反应的速率和立体选择性。还研究了苄氧取代基和α-取代基(氯和甲基)对自由基环化反应的影响。提出了过渡态模型来解释观察到的立体选择性。