一系列酰胺基乙缩醛与布朗斯台德超酸CF 3 SO 3 H反应,通过环化级联反应提供吲哚并咪唑衍生物。提出了一种机理,该机理涉及形成乙烯基的烯醇,该乙烯基的烯醇与相邻的N-酰基亚胺离子基团进行6π-电环化反应。在具有芳基取代基的情况下,N-酰基亚氨基鎓离子基团具有与芳基基团一起进行Friedel-Crafts型环化的强烈趋势。合成方法用于制备生物碱天然产物ipalbidine。
Synthesis of (+)-Ipalbidine Based on 6-exo-trig Radical Cyclization of a β-Amino Radical
摘要:
N-Boc (S)-proline was converted into (2S)-2-[(phenylselanyl)methyl]pyrrolidine, which was alkylated on nitrogen with 2-bromo-1-(4-methoxyphenyl)ethan-1-one. Reaction with vinyl-lithium, 6-exo-trig radical cyclization (Bu3SnH, AIBN, PhMe, 110 degrees C), dehydration (P2O5, H3PO4), and demethylation (BBr3) gave (+)-ipalbidine with ee >99%.
Formal Synthesis of Indolizidine and Quinolizidine Alkaloids from Vinyl Cyclic Carbonates
作者:Àlex Cristòfol、Christian Böhmer、Arjan W. Kleij
DOI:10.1002/chem.201904223
日期:2019.11.27
groups in complex multistep synthetic routes. This study shows that a concise, yet modular synthesis of indolizidine and quinolizidine alkaloids can be developed from vinyl-substituted cyclic carbonate (VCC) intermediates. Through a highly stereoselective palladium-catalyzed allylic alkylation reaction, these alkaloid motifs can be assembled in four synthetic and only two column purification steps. The
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。
A concise total synthesis of (.+-.)-ipalbidine by application of the aldimine-diene cyclocondensation reaction
作者:Samuel J. Danishefsky、Claus Vogel
DOI:10.1021/jo00370a039
日期:1986.10
Synthesis of the alkaloids julandine and ipalbidine-use of silicon (IV) chloride
作者:John E Cragg、Stuart H Hedges、Richard B Herbert
DOI:10.1016/s0040-4039(01)93296-4
日期:1981.1
A Synthesis of (±)-Ipalbidine Using Sulfur-controlled 6-Exo Selective Radical Cyclization of α-Phenylthio Amide
A synthesis of (+/-)-ipalbidine (1) has been achieved using Bu3SnH-mediated 6-exo selective radical cyclization of 2-[3-(phenylthio)prop-2-enyl]-N-[alpha-(p-methoxyphenyl)-alpha-(phenylthio)acetyl]pyrrolidine (15) as a key step.