Copper(II)‐Catalyzed [4+1] Annulation of Propargylamines with <i>N</i>,<i>O</i>‐Acetals: Entry to the Synthesis of Polysubstituted Pyrrole Derivatives

Sakai, Norio; Hori, Hiroaki; Ogiwara, Yohei

doi:10.1002/ejoc.201500098

Cited by 24 publications

(7 citation statements)

References 54 publications

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“…Eluent: n -hexane/EtOAc (9/1) 1 H NMR (400 MHz, CDCl 3 ) δ 7.47 (d, J = 8.4 Hz, 2H), 7.35 (d, J = 8.4 Hz, 2H), 5.42 (d, J = 4.8 Hz, 1H), 2.17 (d, J = 4.8 Hz, 1H), 0.20 (s, 9H) and correspond to literature data. 41 …”

Section: Methodsmentioning

confidence: 99%

Propargylation of CoQ0 through the Redox Chain Reaction

2021

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An efficient catalytic propargylation of CoQ0 is described by employing the cooperative effect of Sc(OTf) 3 and Hantzsch ester. It is suggested to work through the redox chain reaction, which involves hydroquinone and dimeric propargylic moiety intermediates. A broad range of propargylic alcohols can be converted into the appropriate derivatives of CoQ0 containing triple bonds in good to excellent yields. The mechanism of the given transformation is also discussed.

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Section: Methodsmentioning

confidence: 99%

Propargylation of CoQ0 through the Redox Chain Reaction

2021

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“…Sakai reported a [4+1] annulation of propargylamines with either ethyl glyoxalate or phenylglyoxal in the presence of CuCl 2 and piperidine to yield 1,2,5-trisubstituted pyrroles 86. 55 This reaction is proposed to proceed via iminium intermediate 87 resulting from the condensation of glyoxylate ester (or phenylglyoxal) and piperidine. The ensuing sequence of nucleophilic addition by the propargylamine 85, alkyne activation by CuCl 2 to induce 5-endo-dig cyclization, and protonation generates intermediate 88, which undergoes aromatization with loss of piperidine to produce the pyrrole core.…”

Section: Propargylic Groupsmentioning

confidence: 99%

Recent Advancements in Pyrrole Synthesis

Philkhana¹,

Badmus²,

Reis³

et al. 2021

Synthesis

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This review article features selected examples on the synthesis of functionalized pyrroles that were reported between 2014 and 2019. Pyrrole is an important nitrogen-containing aromatic heterocycle that can be found in numerous compounds of biological and material significance. Given its vast importance, pyrrole continues to be an attractive target for the development of new synthetic reactions. The contents of this article are organized by the starting materials, which can be broadly classified into four different types: substrates bearing π-systems, substrates bearing carbonyl and other polar groups, and substrates bearing heterocyclic motifs. Brief discussions on plausible reaction mechanisms for most transformations are also presented.1 Introduction2 From π-Systems2.1 Alkenes2.2 1,6-Dienes2.3 Allenes2.4 Alkynes2.5 Propargylic Groups2.6 Homopropargylic Amines3 From Carbonyl Compounds3.1 Aldehydes3.2 Ketones3.3 Cyanides and Isocyanides3.4 Formamides3.5 β-Enamines3.6 Dicarbonyl Compounds4 From Polar Compounds4.1 Aminols4.2 Diols4.3 Organonitro Compounds5 From Heterocycles5.1 Münchnones5.2 Isoxazoles5.3 Carbohydrates5.4 trans-4-Hydroxy-l-prolines5.5 Pyrrolines6 Summary

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“…In the same year, Sakai and co-workers [54] developed a highly efficient CuCl 2 -catalyzed [4＋1] annulation of propargylamines with N,O-acetals leading to the generation of polysubstituted pyrroles (Scheme 31). Based on this transformation, they further developed a simplified version by employing ethyl glyoxylate and pyrrolidine as N,O-hemiacetal source, which could be converted to the corresponding pyrroles with propargylamines under the catalysis of copper(II) chloride.…”

Section: Scheme 30 Rhodium and Silver-catalyzed Reaction Of Allylamines And Alkenesmentioning

confidence: 99%