- Tandem Synthesis of Tetrasubstituted NH Pyrroles from Simple Nitriles
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An efficient tandem route to obtain tetrasubstituted NH pyrroles in a one-pot manner has been developed, staring from simple nitriles, ethyl bromoacetates, and zinc. This reaction involves oxidative dimerization of the zinc bromide complex of β-enaminoesters using cerium ammonium nitrate (CAN) as an oxidant, affording 2,3,4,5-tetrasubstituted pyrroles in yields up to 91%.
- Kim, Hyeongsu,Xuan, Zi,Hyun Kim, Ju
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supporting information
p. 3336 - 3340
(2021/09/09)
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- Synthesis of Polycarbonyl Pyrroles via K2S2O8-Mediated Oxidative Cyclization of Enamines
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A novel K2S2O8-promoted oxidative cyclization of enamines is described. A variety of enamines having diverse functional groups and substitution patterns react well using K2S2O8 as the oxidant in the absence of catalyst. This protocol provides a very simple route for the synthesis of polycarbonyl pyrroles and has the advantages of readily available starting materials, mild reaction conditions, and a wide scope of substrates.
- Gao, Peng,Wang, Juan,Bai, Zi-Jing,Shen, Li,Yan, Yun-Yun,Yang, De-Suo,Fan, Ming-Jin,Guan, Zheng-Hui
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supporting information
p. 6074 - 6077
(2016/12/09)
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- Site-Selective Silylation of Aliphatic C-H Bonds Mediated by [1,5]-Hydrogen Transfer: Synthesis of α-Sila Benzamides
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The first example of site-selective silylation of C(sp3)-H bonds mediated by a [1,5]-hydrogen transfer is reported. This reaction occurs selectively at the α-position of benzamides with a combination of tert-butylmagnesium chloride and a catalytic amount of 4,4′-di-tert-butylbipyridine (dtbpy) ligand and provides a facile route for the creation of biologically interesting α-sila benzamides. Late-stage functionalization of the incorporated silyl moieties facilitates the synthesis of N-formyl, cis-enamine, β-hydroxyl, amino, and pyrrole-containing derivatives.
- Liu, Pei,Tang, Jinghua,Zeng, Xiaoming
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supporting information
p. 5536 - 5539
(2016/11/17)
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- Visible-light-induced formal [3+2] cycloaddition for pyrrole synthesis under metal-free conditions
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A photocatalytic formal [3+2] cycloaddition of 2H-azirines with alkynes has been achieved under irradiation by visible light in the presence of organic dye photocatalysts. This transformation provides efficient access to highly functionalized pyrroles in good yields and has been applied to the synthesis of drug analogues. A primary trial of photocascade catalysis merging energy transfer and redox neutral reactions was shown to be successful. Photo(chemistry) op: A photocatalytic formal [3+2] cycloaddition of 2H-azirines with alkynes has been established under the irradiation of visible light in the presence of an organic dye. This transformation provides efficient access to highly functionalized pyrroles in good yields and has been applied to the formal synthesis of an inhibitor for HMG-CoA reductase.
- Xuan, Jun,Xia, Xu-Dong,Zeng, Ting-Ting,Feng, Zhu-Jia,Chen, Jia-Rong,Lu, Liang-Qiu,Xiao, Wen-Jing
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p. 5653 - 5656
(2014/06/10)
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- Synthesis of polysubstituted pyrroles via phi(OAC)2-mediated oxidative coupling of enamine esters and ketones
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Enamine esters or ketones could undergo homocoupling by the action of (diacetoxyiodo)benzene in the presence of BF3OEt2, giving rise to pyrrole products. This reaction could be used to synthesize symmetric polysubstituted pyrroles. Some asymmetric polysub
- Wang, Jun-Yan,Liu, Su-Ping,Yu, Wei
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experimental part
p. 2529 - 2533
(2010/02/28)
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- Task-specific basic ionic liquid: A reusable and green catalyst for one-pot synthesis of highly functionalized pyrroles in aqueous media
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A basic functionalized ionic liquid, 1-butyl-3-methylimidazolium hydroxide ([bmim]OH), catalyzed the three-component condensation reaction of acid chlorides, amino acids, and dialkyl acetylenedicarboxylates in water to afford functionalized pyrroles in high yields. Georg Thieme Verlag Stuttgart.
- Yavari, Issa,Kowsari, Elaheh
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p. 897 - 899
(2008/12/22)
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- Novel generation and cycloaddition of N-silylated azomethine ylides from α-silylimidates and trifluorosilane
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The Generation of N-silylated azomethine ylides was achieved by the reaction of α-silylimidates and trifluorophenylsilane. The generated azomethine ylides can be regarded as synthetic equivalents of nitrile ylides since they have an alkoxy group which may
- Washizuka, Ken-Ichi,Minakata, Satoshi,Ilhyong, Ryu,Komatsu, Mitsuo
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p. 12969 - 12976
(2007/10/03)
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- Synthesis of Pyrrole Derivatives Using Thioimidates
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Dimethyl acetylenedicarboxylate, ethyl propiolate, nitro olefins, or 2-nitroalkyl acetates react with thioimidate in the presence of organic bases to give the corresponding pyrroles in moderate-to-good yields.
- Yokoyama, Masataka,Menjo, Yasuhiro,Wei, He,Togo, Hideo
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p. 2735 - 2738
(2007/10/03)
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- Physical Aspects of N-Benzoylaziridine Photochemistry. Characterization of Azomethine Ylides and Related Photointermediates
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Results of a time-resolved study based on nanosecond laser flash photolysis are presented for phototransients derived from three N-benzoylaziridines in fluid solutions.The major transients, best assigned as azomethine ylides, are characterized by two maxima (380 - 440 and 560 - 610 nm) in the absorption spectrum in the visible region and by microsecond lifetimes at room temperature (τY = 0.2 - 31 μs); these are sluggish in their reactivity toward dimethyl acetylenedicarboxylate kqY 4 M-1 s-1 in benzene).Relatively short-lived triplets (τT = 1-90 ns in benzene) quenchable by biphenyl and 2,5-dimethyl-2,4-hexadiene, act as precursors for the ylides.Between trans-1-benzoyl-2,3-diphenylaziridine (1a) and its cis isomer (1b), τT is considerably shorter for the former (1 ns for 1a vs 40 ns for 1b, on the basis of the assumption that the rate constant for triplet quenching by 2,5-dimethyl-2,4-hexadiene is 2 * 109 M-1 s-1 in benzene); this is explainable in terms of efficient intramolecular quenching of the benzamide-type triplet by a β-phenyl group in 1a while this interaction is less favorable in the most stable conformer of 1b (wherein the benzoyl moiety protrudes away from the cis phenyl groups).Steady-state photolysis and product analysis studies have provided evidence for photocleavage of both C-N and C-C bonds of the aziridine ring.
- Ramaiah, D.,Cyr, D. R.,Barik, R.,Gopidas, K. R.,Das, P. K.,George, M. V.
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p. 1271 - 1278
(2007/10/02)
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- The synthesis of pyrroles and dihydropyrroles by 1,3-dipolar cyclisations of N-arylmethylene[(benzotriazol-1-yl)arylmethyl]amines
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N-Arylmethylene[(benzotriazol-1-yl)arylmethyl]amines 1 are prepared by the reaction of arylaldehydes, benzotriazole, and ammonia in dry ethanol. Deprotonation of these imines with butyllithium yields N-lithiated azomethine ylides 2 which readily undergo 1,3-dipolar cycloaddition with a large range of dipolarophiles. The cyclisations are regiospecific and generally exhibit high stereoselectivity. Benzotriazolate is eliminated during the course of the reaction, and the method thereby provides a route to 2,5-diaryl substituted pyrroles, 3,4-dihydro-2H-pyrroles and c-ring fused 3,4-dihydro-2H-pyrroles.
- Katritzky,Hitchings,Zhao
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p. 863 - 867
(2007/10/02)
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- Novel generation of azomethine ylide from N-(α-silylbenzyl)amide by silicon shift: An equivalent of nitrile ylide
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Azomethine ylides were generated from N-(α-silylbenzyl)amides by thermal silicon shift to the oxygen and trapped with dipolarophiles to give the same products as those from the corresponding nitrile ylides via elimination of silanol.
- Ohno,Komatsu,Miyata,Ohshiro
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p. 5813 - 5816
(2007/10/02)
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- Reactions of cobaltacyclopentadiene complexes with organic azides directed toward synthesis of highly substituted pyrroles
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The reactions of the cobaltacyclopentadiene complexes (η5-C5H5)(PPH3)-Co(-CR1=CR2-CR3=CR4)- (I) with organic azides were investigated.The complex Ia (R1)=R2=R3=R4=Ph) reacts with phenyl azide at 80 degC to give 1,2,3,4,5-pentaphenylpyrrole in 73percent yeld.Similarly, the reactions of Ia with benzoyl and t-butoxycarbonyl azides give 1-benzoyl- and 1-(t-butoxycarbonyl)-2,3,4,5-tetraphenylpyrroles in 41 and 64percent yields, respectively, but reaction with p-toluenesulfonyl azide gives 2,3,4,5-tetraphenylpyrrole and 3,4,5,6-tetraphenylpyridazine in 35 and 45percent yields, respectively, in place of the expected 1-(p-toluenesulfonyl)-2,3,4,5-tetraphenylpyrrole.The reaction of Ic (R1=R4=Ph, R2=R3=CO2CH3) with phenyl azide at 130 degC gives 1,2,5-triphenyl-3,4-bis(methoxycarbonyl)pyrrole (IIc)and 2,5-diphenyl-3,4-bis(methoxcarbonylpyrrole (Vb) in 22 and 15percent yields, respectively.The reaction of Ic with benzenesulfonyl azide gives only Vb in 57percent yield.In the reaction of Id (R1=R3=Ph, R2=R4=CO2CH3) with benzenesulfonyl azide, Vb was unexpectedly obtained in 26percent yield, together with 2,4-diphenyl-3,5-bis(methoxycarbonyl)pyrrole (Vc, 30percent), which suggests that a skeletal rearrangement of the metallacycle IXd to IXc occurs during the reaction.The reaction of Ic or Id with benzoyl azide at 130 degC gives the 2(1H)-pyridinone derivatives VIIIa (82percent) and VIIIb (53percent), which are the products of the reaction of the corresponding cobaltacyclpentadiene with phenyl isocyanate generated by the rearrangement of benzoyl nitrene, in place of the expected, corresponding pyrrole.
- Hong, Pangbu,Yamazaki, Hiroshi
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p. 133 - 142
(2007/10/02)
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- Benzylidene(cyano)benzylamine as a 1,3-Dipole
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Benzylidene(cyano)benzylamine reacted as an azomethine ylide with DMAD and olefinic dipolarophiles.In most cases, however, the products derived from the initially formed cycloadducts with the elimination of hydrogen cyanide were obtained.
- Tsuge, Otohiko,Ueno, Kazunori
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p. 1411 - 1414
(2007/10/02)
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