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.
Total Synthesis of Indolizidine Alkaloids via Nickel-Catalyzed (4 + 2) Cyclization
作者:Jonas Renner、Ashish Thakur、Philipp M. Rutz、Jacob M. Cowley、Judah L. Evangelista、Puneet Kumar、Matthew B. Prater、Ryan M. Stolley、Janis Louie
DOI:10.1021/acs.orglett.9b04479
日期:2020.2.7
azetidinones toward piperidinones was used as key reaction in the enantioselective synthesis of naturally occurring indolizidine alkaloids. The reaction benefits from the use of an easily accessible azetidinone as an advanced and divergent intermediate to build the indolizidine core. This methodology has been applied in the total syntheses of (+)-septicine, (+)-ipalbidine, and (+)-seco-antofine to illustrate
A Simple Enantioselective Route to Functionalized Indolizidines: Synthesis of (+)-Ipalbidine and (+)-Antofine
作者:Sunil V. Pansare、Rajinikanth Lingampally、Rajendar Dyapa
DOI:10.1002/ejoc.201100125
日期:2011.4
efficient route to functionalizedindolizidines from an enantiomerically enriched γ-nitro ketone is described. The nitro ketone is obtained by an organocatalytic, enantioselective ketone-nitro alkene Michael addition. Oxidative ring expansion of the nitro ketone and subsequent methanolysis provides a 8-nitro-4-oxooctanoate. This is stereoselectively transformed to the key, functionalizedindolizidine intermediate