A catalytic dipolar cycloaddition route to pyrroloimidazoles

Jones, Raymond C. F.; Iley, Jim; Sanchis-Amat, Maria; Zhang, Xiaohui; Elsegood, Mark R. J.

doi:10.1016/j.tetlet.2009.03.064

Cited by 8 publications

(3 citation statements)

References 11 publications

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“…Owing to the methyl substituent the charge delocalization by the carboxylate moiety is asymmetric with d (C9−O1)=1.384(2) Å and d (C9−O2)=1.232(2) Å, which contrasts with the very symmetric zwitterion 4 (see the Supporting Information for further bond lengths of 4 ). The bond distances and angles of 15 are in good agreement with the related N , N′ ‐diorgano‐2‐ethoxycarbonylmethylenebenzimidazole structure . In 15 , similarly to the reference structure, the olefinic hydrogen atom is oriented towards the smaller N ‐methyl group, whereas the alkoxycarbonyl group is oriented towards the larger N ‐ethyl substituent.…”

Section: Resultsmentioning

confidence: 94%

“…The bond distances and angles of 15 are in good agreement with the related N,N'-diorgano-2-ethoxycarbonylmethylenebenzimidazole structure. [34] In 15,s imilarly to the reference structure, the olefinic hydrogen atom is oriented towards the smaller N-methyl group, whereas the alkoxycarbonyl group is oriented towards the larger N-ethyl substituent. The 2D H,H NOESY NMR spectra of 15 in [D 8 ]toluene at 25 and À50 8C…”

Section: Furtherc àCc Oupling Reactions Of the Nho-co 2 Adductmentioning

confidence: 96%

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N‐Heterocyclic Olefin–Carbon Dioxide and –Sulfur Dioxide Adducts: Structures and Interesting Reactivity Patterns

Finger

Guschlbauer

Harms

2016

Chemistry A European J

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Depending on the amount of methanol present in solution, CO adducts of N-heterocyclic carbenes (NHCs) and N-heterocyclic olefins (NHOs) have been found to be in fully reversible equilibrium with the corresponding methyl carbonate salts [EMIm][OCO Me] and [EMMIm][OCO Me]. The reactivity pattern of representative 1-ethyl-3-methyl-NHO-CO adduct 4 has been investigated and compared with the corresponding NHC-CO zwitterion: The protonation of 4 with HX led to the imidazolium salts [NHO-CO H][X], which underwent decarboxylation to [EMMIm][X] in the presence of nucleophilic catalysts. NHO-CO zwitterion 4 can act as an efficient carboxylating agent towards CH acids such as acetonitrile. The [EMMIm] cyanoacetate and [EMMIm] cyanomalonate salts formed exemplify the first C-C bond-forming carboxylation reactions with NHO-activated CO . The reaction of the free NHO with dimethyl carbonate selectively led to methoxycarbonylated NHO, which is a perfect precursor for the synthesis of functionalized ILs [NHO-CO Me][X]. The first NHO-SO adduct was synthesized and structurally characterized; it showed a similar reactivity pattern, which allowed the synthesis of imidazolium methyl sulfites upon reaction with methanol.

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Section: Resultsmentioning

confidence: 94%

Section: Furtherc àCc Oupling Reactions Of the Nho-co 2 Adductmentioning

confidence: 96%

N‐Heterocyclic Olefin–Carbon Dioxide and –Sulfur Dioxide Adducts: Structures and Interesting Reactivity Patterns

Finger

Guschlbauer

Harms

2016

Chemistry A European J

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“…Scheme 1), 3 or (ii) a catalytic cycle of metal carbenoid insertion onto the imine N-atom. 4 The diastereoselection is rationalised by an anti dipole conformation and endo approach of dipole to dipolarophile (Scheme 1) to establish the stereochemistry at C-5 and C-7 of the cycloadducts.…”

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confidence: 99%

Imidazolium ylides from a conjugate addition–proton transfer route and their cycloaddition reactions

et al. 2011

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Gold‐Catalyzed [3+2]/Retro‐[3+2]/[3+2] Cycloaddition Cascade Reaction of N‐Alkoxyazomethine Ylides

et al. 2017

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Anovel cascade reaction has been developed for the synthesis of 2,6-methanopyrrolo [1,2-b]isoxazoles based on the gold-catalyzed generation of an N-allyloxyazomethine ylide. This reaction involves sequential [3+ +2]/retro-[3+ +2]/[3+ +2] cycloaddition reactions,t hus providing facile access to fused and bridged heterocycles which would be otherwise difficult to prepare using existing synthetic methods.Notably,this reaction allows the efficient construction of three CÀCbonds,one CÀO bond, one CÀNb ond and one CÀHb ond, as well as the cleavage of one CÀCbond, one CÀObond and one CÀHbond in as ingle operation. The intermolecular cycloaddition of an N-allyloxyazomethine ylide and the subsequent application of the product to the synthesis of tropenol is also described. Scheme 1. Cycloadditions cascade of N-alkoxyazomethine ylide.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: http://dx.

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A catalytic dipolar cycloaddition route to pyrroloimidazoles

Cited by 8 publications

References 11 publications

N‐Heterocyclic Olefin–Carbon Dioxide and –Sulfur Dioxide Adducts: Structures and Interesting Reactivity Patterns

N‐Heterocyclic Olefin–Carbon Dioxide and –Sulfur Dioxide Adducts: Structures and Interesting Reactivity Patterns

Imidazolium ylides from a conjugate addition–proton transfer route and their cycloaddition reactions

Gold‐Catalyzed [3+2]/Retro‐[3+2]/[3+2] Cycloaddition Cascade Reaction of N‐Alkoxyazomethine Ylides

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