Cascade Cyclizations of Acyclic and Macrocyclic Alkynones: Studies toward the Synthesis of Phomactin A
作者:Jennifer Ciesielski、Vincent Gandon、Alison J. Frontier
DOI:10.1021/jo4007514
日期:2013.10.4
closure, while cyclizations using BF3·OEt2 as promoter occurred reversibly. For both acyclic and macrocyclic alkynones, high diastereoselectivity was observed in the intramolecular aldol reaction. The MgI2 protocol for cyclization was applied to the synthesis of advanced intermediates relevant to the synthesis of phomactin natural products, during which a novel transannular cation–olefin cyclization was
描述了路易斯酸促进的无环和大环炔酮的级联环化的反应性和非对映选择性的研究。在这些反应中,β-碘代烯醇酯中间体是通过碘化物与炔酮的共轭加成,然后与束缚醛进行分子内醛醇反应生成环己烯醇而产生的。发现路易斯酸碘化镁(MgI 2)促进不可逆的闭环,而使用BF 3 ·OEt 2作为促进剂的环化反应可逆地发生。对于无环和大环炔酮,在分子内醛醇反应中观察到高非对映选择性。MgI 2环化协议应用于合成与 phomactin 天然产物合成相关的高级中间体,在此期间观察到了一种新型的跨环阳离子 - 烯烃环化。进行 DFT 计算以分析这种不寻常的 MgI 2促进过程的机制。