- Free-radical cyclization approach to polyheterocycles containing pyrrole and pyridine rings
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A wide range of derivatives with new pyrido[2,1-a]pyrrolo[3,4-c]isoquinoline skeleton was synthesized by free-radical intramolecular cyclization of o-bromophenyl-substituted pyrrolylpyridinium salts using the (TMS)3SiH/AIBN system. The cyclizat
- Khlebnikov, Alexander F.,Mosiagin, Ivan P.,Novikov, Mikhail S.,Spiridonova, Darya V.,Tomashenko, Olesya A.,Tunik, Sergey P.
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supporting information
p. 1490 - 1498
(2021/07/02)
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- Silver-Promoted (4 + 1) Annulation of Isocyanoacetates with Alkylpyridinium Salts: Divergent Regioselective Synthesis of 1,2-Disubstituted Indolizines
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An unprecedented silver-promoted regioselective (4 + 1) annulation of isocyanoacetates with pyridinium salts is reported. The established protocol provides controlled, facile, and modular access to a range of synthetically useful N-fused heterocyclic scaffolds containing indolizines, pyrrolo[1,2-a]quinolines, pyrrolo[2,1-a]isoquinolines, and 1H-imidazo[4,5-a]indolizin-2(3H)-ones. A mechanistic pathway involving nucleophilic addition/protonation/elimination/cycloisomerization is proposed.
- Chen, Yan,Shatskiy, Andrey,Liu, Jian-Quan,K?rk?s, Markus D.,Wang, Xiang-Shan
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supporting information
p. 7555 - 7560
(2021/10/02)
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- Diversified Transformations of Tetrahydroindolizines to Construct Chiral 3-Arylindolizines and Dicarbofunctionalized 1,5-Diketones
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Enantioselective diverse synthesis of a small-molecule collection with structural and functional similarities or differences in an efficient manner is an appealing but formidable challenge. Asymmetric preparation and branching transformations of tetrahydroindolizines in succession present a useful approach to the construction of N-heterocycle-containing scaffolds with functional group, and stereochemical diversity. Herein, we report a breakthrough toward this end via an initial diastereo- A nd enantioselective [3 + 2] cycloaddition between pyridinium ylides and enones, following diversified sequential transformations. Chiral N,N′-dioxide-earth metal complexes enable the generation of optically active tetrahydroindolizines in situ, across the strong background reaction for racemate-formation. In connection with deliberate sequential transformations, involving convenient rearomatic oxidation, and light-active aza-Norrish II rearrangement, the tetrahydroindolizine intermediates were converted into the final library including 3-arylindolizine derivatives and dicarbofunctionalized 1,5-dicarbonyl compounds. More importantly, the stereochemistry of four-stereogenic centered tetrahydroindolizine intermediates could be efficiently transferred into axial chirality in 3-arylindolizines and vicinal pyridyl and aryl substituted 1,5-diketones. In addition, densely functionalized cyclopropanes and bridged cyclic compounds were also discovered depending on the nature of the pyridinium ylides. Mechanism studies were involved to explain the stereochemistry during the reaction processes.
- Feng, Xiaoming,He, Qianwen,Liu, Xiaohua,Pan, Chenjing,Su, Zhishan,Wu, Zhikun,Zhang, Dong,Zhou, Yuqiao
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supporting information
p. 15975 - 15985
(2020/10/18)
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- Facile one-pot tandem synthesis of perfluoroalkylated indolizines under metal-free mild conditions
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A direct metal-free method for the synthesis of perfluoroalkylated indolizines by means of DIPEA-promoted tandem C[sbnd]N/C[sbnd]C bond formation was developed. Various substituted pyridines and bromoacetyl derivatives with methyl perfluoroalk-2-ynoates proceeded smoothly in this mild transformation, and the desired products were obtained in good to excellent yields under air.
- He, Dong,Xu, Yuhong,Han, Jing,Deng, Hongmei,Shao, Min,Chen, Jie,Zhang, Hui,Cao, Weiguo
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p. 938 - 944
(2017/01/25)
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- Transition-Metal-Free Synthesis of Indolizines from Electron-Deficient Alkenes via One-Pot Reaction Using TEMPO as an Oxidant
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A one-pot method for the synthesis of multisubstituted indolizines from α-halo carbonyl compounds, pyridines, and electron-deficient alkenes is reported. The oxidative dehydrogenation reaction takes place under transition-metal-free conditions using TEMPO as an oxidant. This protocol uses ready available starting materials in a convenient procedure under mild reaction conditions.
- Shi, Fei,Zhang, Yu,Lu, Zhaole,Zhu, Xiaolei,Kan, Weiqiu,Wang, Xiang,Hu, Huayou
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p. 413 - 420
(2016/01/28)
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- One-pot synthesis of indolizine via 1,3-dipolar cycloaddition using a sub-equivalent amount of K2Cr2O7 as an efficient oxidant under base free conditions
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A one-pot method for synthesizing multi-substituted indolizines from α-halo-carbonyl compounds, pyridines and electron deficient alkenes was developed. A sub-equivalent amount of potassium dichromate was used as an oxidant under base free conditions. The transformation developed should be of economic efficiency.
- Wang, Chao,Hu, Huayou,Xu, Juanfang,Kan, Weiqiu
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p. 41255 - 41258
(2015/05/20)
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- Copper acetate monohydrate: A cheap but efficient oxidant for synthesizing multi-substituted indolizines from pyridinium ylides and electron deficient alkenes
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We report a highly practical one-pot method for synthesizing multi-substituted indolizines from ?±-halide carbonyl compounds, pyridines and electron deficient alkenes in the presence of copper acetate monohydrate and sodium acetate in DMF. A variety of function groups are tolerable in standard reaction conditions, including aldehyde. 36 examples were presented. The yield of indolizine was from moderate to high. Furthermore, multi-substituted indolizines can be prepared at gram scale by this method.
- Hu, Huayou,Feng, Junjun,Zhu, Yulan,Gu, Ning,Kan, Yuhe
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p. 8637 - 8644
(2015/02/19)
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