Darstellung von Imidazoliden. Synthese von Amiden, Hydraziden und Hydroxamsäuren nach der Imidazolidmethode

Staab, Heinz A.; Lüking, Martin; Dürr, F.

doi:10.1002/cber.19620950526

Cited by 146 publications

(34 citation statements)

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“…1-Benzoyl-3-phenyl-1,2,4-triazole (1a) and 1-benzoyl-1,2,4-triazole were synthesised according to literature procedures. 13,59,60 Kinetic Experiments. Aqueous solutions were prepared by weight immediately before use.…”

Section: Methodsmentioning

confidence: 99%

General‐base catalysed hydrolysis and nucleophilic substitution of activated amides in aqueous solutions

Buurma

Blandamer

Engberts

2003

J of Physical Organic Chem

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General-base catalysed hydrolysis and nucleophilic substitution of activated amides in aqueous solutions Buurma, NJ; Blandamer, MJ; Engberts, Jan; Buurma, Niklaas J. Other than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. ABSTRACT: The reactivity of 1-benzoyl-3-phenyl-1,2,4-triazole (1a) was studied in the presence of a range of weak bases in aqueous solution. A change in mechanism is observed from general-base catalysed hydrolysis to nucleophilic substitution and general-base catalysed nucleophilic substitution. A slight tendency is also observed for the more hydrophobic general bases to show higher reactivity towards 1a. Aspartame is an effective nucleophile, possibly because nucleophilic substitution is subject to intramolecular general-base catalysis. A general conclusion derived from the present results is that unexpected rate effects can only be rationalised provided that the detailed reaction mechanisms are well understood. Copyright  2003 John Wiley & Sons, Ltd.KEYWORDS: hydrolysis; changes in mechanism; general-base catalysis; general-acid catalysis; nucleophilic substitution INTRODUCTIONThe hydrolysis reaction of the activated amide 1-benzoyl-3-phenyl-1,2,4-triazole (1a) is general-base catalysed (Scheme 1). 1In highly aqueous solutions, the concentration of water is sufficiently high for water to act (detectably) as both a general base and a nucleophile. Hence, in the absence of other general bases, the water-catalysed (i.e. pHindependent) hydrolysis is the sole reaction. In the presence of sufficiently basic cosolutes, the watercatalysed reaction is unimportant. More basic cosolutes are much more effective catalysts for hydrolysis than water. Consequently, despite the relatively low molality of added general bases, the general-base catalysed hydrolysis pathway competes with the water-catalysed pathway. It is stressed that even though in the watercatalysed reaction the second water molecule in the activated complex (i.e. B = H 2 O, Scheme 1) acts as a general base, a distinction is drawn between the watercatalysed reaction and general-base catalysed reaction.Increased basicity of cosolutes usually leads to a concomitant increase in nucleophilicity. This increase in nucleophilicity provides an alternative reaction pathway: nucleophilic attack on the carbonyl functionality, followed by loss of the (substituted) 1,2,4-triazole leaving group (Scheme 2).In this mechanism, the nucleophilic water molecule is replaced by a stronge...

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Section: Methodsmentioning

confidence: 99%

General‐base catalysed hydrolysis and nucleophilic substitution of activated amides in aqueous solutions

Buurma

Blandamer

Engberts

2003

J of Physical Organic Chem

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“…We believe that the large Stokes shifts are a consequence of the twist observed for the 7-aryl substituent in the ground state (see above). structural relaxation in the excited singlet state would lead to a coplanar conformation of the aryl ring and the imidazo[1, 2-a] The 1 -(arylacetyl)imidazoles 1, I-(arylacety1)-I ,2,4-triazoles 9, and 1 -(arylacetyl)benzimidazoles 11 were prepared by adaption of literature procedures using the reagent introduced by Staab2',27) (Method A), by a modified GerngroD procedure3*', which is especially useful for the regioselective synthesis of 4,5-unsymmetrically substituted I-(arylacety1)imidazoles (Method B), and by a further modification of the GerngroD procedure, which has been reported by Rege123b) (Method C).…”

Section: Fluorescence Propertiesmentioning

confidence: 99%

Imidazole Derivatives, III. Regiospecific Synthesis,Structure, and Fluorescence Properties of Highly substituted Imidazo[1,2‐a]pyridines and Pyrido[1,2‐a]benzimidazoles

Knölker

Hitzemann

Boese³

1990

Chem. Ber.

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1‐(Arylacetyl)imidazoles 1 react with acetylenedicarboxylic esters to provide highly functionalized imidazo[1,2‐a]pyridines 2 in up to 89% yield. The scope and limitations of this novel condensation reaction have been investigated, ad a mechanistic interpretation is presented. A strong effect on the yield of this reaction is observed for electron‐donating and electronwithdrawing substituents in the para position of the aryl ring. Moreover, the transformation is shown to proceed in a regiospecific manner starting with 4,5‐unsymmetrically substituted 1‐(arylacetyl)imidazoles (1d–g) and is extended to the synthesis of the corresponding pyrido[1,2‐a]benzimidazoles 12. The crystal structure of derivative 2a has been determined by X‐ray analysis. Imidazo[1,2‐a]pyridines 2 and pyrido[1,2‐a]‐benzimidazoles 12, obtained by this procedure, are highly fluorescent in the visible region with characteristically large Stokes shifts.

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“…[16][17][18] Using the conditions of Masuda, 18e we began a study on the synthesis of arylboronic esters using Pd catalysts (Table 1). The best yield was obtained using PdCl 2 (dppf) as catalyst (Table 1, entries 1 and 2).…”

Section: Resultsmentioning

confidence: 99%

“…Low yields of the desired borylated compound (2a) were achieved using K 2 CO 3 as base (see Table 1, entries 8 and 9). A further 13 amide-acetal substrates (1) (Scheme 2) 16 were screened. The reactions were monitored using TLC analysis with alizarin dye 20 (see ESI †).…”

Section: Resultsmentioning

confidence: 99%

Transition-metal-catalyzed intramolecular cyclization of amido(hetero)arylboronic acid aldehydes to isoquinolinones and derivatives

2015

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We report an innovative and simple three step high yielding synthesis of a library of 14 chiral isoquinolinone and azepinone derivatives with benzyl, pyridyl and thiophene cores starting from amidoarylboronic acid aldehydes. These products have potential for treating neurodegenerative diseases. The key reaction in this synthetic pathway was an efficient metal-catalyzed (with Rh, Cu and Pd catalysts) intramolecular cyclization. A maximum yield of 87% was obtained using a Rh(I) catalyst.

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Darstellung von Imidazoliden. Synthese von Amiden, Hydraziden und Hydroxamsäuren nach der Imidazolidmethode

Cited by 146 publications

References 20 publications

General‐base catalysed hydrolysis and nucleophilic substitution of activated amides in aqueous solutions

General‐base catalysed hydrolysis and nucleophilic substitution of activated amides in aqueous solutions

Imidazole Derivatives, III. Regiospecific Synthesis,Structure, and Fluorescence Properties of Highly substituted Imidazo[1,2‐a]pyridines and Pyrido[1,2‐a]benzimidazoles

Transition-metal-catalyzed intramolecular cyclization of amido(hetero)arylboronic acid aldehydes to isoquinolinones and derivatives

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