Iminium Ion–Enamine Cascade Cyclizations: Facile Access to Structurally Diverse Azacyclic Compounds and Natural Products
作者:Stephen Hanessian、Amit Kumar Chattopadhyay
DOI:10.1021/ol403229q
日期:2014.1.3
A one-pot, mild, two-component iminium ion–enamine cascade reaction to construct structurally diverse azacyclic frameworks from l-proline and l-pipecolic acid, and its application to indolizidine and quinolizidine alkaloids and azasteroids, is reported.
Improved Total Synthesis of Indolizidine and Quinolizidine Alkaloids via Nickel-Catalyzed (4 + 2) Cycloaddition
作者:Jonas Renner、Sleight R. Smith、Jacob M. Cowley、Janis Louie
DOI:10.1021/acs.joc.2c00365
日期:2022.7.15
A Ni-catalyzed (4 + 2) cycloaddition of bicyclic 3-azetidinones and alkynes was developed to access indolizidine and quinolizidine alkaloids. A key element was the development of a diazomethylation procedure that allows the efficient synthesis of bicyclic azetidinones from pyroglutamic and 6-oxopiperidine-2-carboxylic acid. A ligand screening led to improved regioselectivity and enantiopurity during
开发了双环 3-氮杂环丁酮和炔烃的 Ni 催化 (4 + 2) 环加成反应来获得吲哚里西啶和喹里西啶生物碱。一个关键因素是重氮甲基化过程的开发,该过程允许从焦谷氨酸和 6-氧代哌啶-2-羧酸有效合成双环氮杂环丁酮。在 Ni 催化的 (4 + 2) 环加成过程中,配体筛选提高了区域选择性和对映纯度。利用这种简单的方法合成 (+)-ipalbidine、(+)-septine、(+)- seco -antofine 和 (+)-7-methoxy-julandine。
Total Syntheses of Arylindolizidine Alkaloids (+)-Ipalbidine and (+)-Antofine
作者:Micah J. Niphakis、Gunda I. Georg
DOI:10.1021/jo101051w
日期:2010.9.3
This paper presents the first application of two recently developed reactions to natural product synthesis. The first method involves a 6-endo-trig cyclization to prepare a versatile chiral enaminone building block. The second is a direct C-H arylation reaction. As a showcase for the utility of these methods, (+)-antofine and (+)-ipalbidine were synthesized in only 8 steps and 24-26% overall yields.