A Bifunctional Lewis Acid Induced Cascade Cyclization to the Tricyclic Core of ent-Kaurenoids and Its Application to the Formal Synthesis of (±)-Platensimycin
摘要:
A mild and efficient bifunctional Lewis acid induced cascade cyclization reaction has been developed for construction of the tricyclic core of ent-kaurenolds. With ZnBr2 as the bifunctional Lewis acid, a series of substituted enones and dienes underwent cascade cyclization smoothly at room temperature and provided the tricyclic products in one pot with good yields (75-91%) and high diastereoselectivity. The cyclized product has been successfully employed for the formal synthesis of (+/-)-platenslmycln.
Construction of Angularly Fused Tricyclic Compounds via Photo‐induced Radical Cascade Cyclization
作者:Mengqin Hu、Wei Cao、Zhen Wang、Yan Hao、Ganxing Huang、Yuqiao Zhou、Song Qin、Shaomin Fu、Bo Liu
DOI:10.1002/cjoc.202300246
日期:2023.10
(PET) of silyl enol ethers has been employed to synthesize several fused ring systems. However, the method has limited applicability due to its narrow substrate scope, low product yields, unsatisfactory stereo- and regioselectivity. Herein, we report a PET-triggered cascade reaction of silyl enolates that leads to the formation of angularly fused tricyclic scaffolds. The reaction exhibits broad substrate
硅烯醇醚的光诱导电子转移(PET)已被用来合成多种稠环系统。然而,由于底物范围窄、产物收率低、立体选择性和区域选择性不理想,该方法的适用性受到限制。在此,我们报道了 PET 触发的甲硅烷基烯醇化物级联反应,导致形成有角度稠合的三环支架。该反应表现出广泛的底物范围和优异的立体选择性。通过 DFT 计算和构象分析阐明了该级联反应的区域选择性和立体选择性。