1,3‐Dipolar Cycloaddition Reactions of Organic Azides with Morpholinobuta‐1,3‐dienes and with an <i>α</i>‐Ethynyl‐enamine

Brunner, Martina; Maas, Gerhard; Klärner, Frank‐Gerrit

doi:10.1002/hlca.200590142

Cited by 33 publications

(11 citation statements)

References 26 publications

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“…In contrast to the 1,4-disubstituted- 1H- 1,2,3-triazoles, general and regioselective routes leading to the 1,5-regioisomers are not as well developed 3–8. Although syntheses relying on the nucleophilic attack by the acetylide at the electrophilic terminal nitrogen of the azide are known,9 the requirement for the stoichiometric lithium or magnesium acetylide reagent imposes obvious limitations on the range of functional groups that are compatible with these processes.…”

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confidence: 99%

Transition-Metal-Free Catalytic Synthesis of 1,5-Diaryl-1,2,3-triazoles

et al. 2010

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Abstract1,5-Diarylsubstituted 1,2,3-triazoles are formed in high yield from aryl azides and terminal alkynes in DMSO in the presence of catalytic tetraalkyl ammonium hydroxide. The reaction is experimentally simple, does not require a transition-metal catalyst, and is not sensitive to atmospheric oxygen and moisture.The copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) is a reliable means for the synthesis of 1,4-disubstituted-1H-1,2,3-triazoles. 1 The exceptional stability of 1,2,3-triazoles and the availability of a reliable synthesis leading to these heterocycles have enabled widespread applications of this previously underutilized class of azoles in medicinal chemistry, chemical biology and materials science. 2 In contrast to the 1,4-disubstituted-1H-1,2,3-triazoles, general and regioselective routes leading to the 1,5-regioisomers are not as well developed. [3][4][5][6][7][8] Although syntheses relying on the nucleophilic attack by the acetylide at the electrophilic terminal nitrogen of the azide are known, 9 the requirement for the stoichiometric lithium or magnesium acetylide reagent imposes obvious limitations on the range of functional groups that are compatible with these processes. Reported here is a mild and experimentally simple catalytic method for the generation of the reactive acetylides which readily react with organic azides resulting in the exclusive formation of 1,5-disubstituted triazoles.We envisioned that the high acidity of aryl acetylenes in dimethylsulfoxide [10][11][12] should allow formation of the reactive acetylide species by treatment of the alkyne with a hydroxide or fokin@scripps.edu. Supporting Information Available. Experimental procedures, characterization data, copies of 1 H NMR and 13 C NMR spectra. This material is available free of charge on the Internet at http://pubs.acs.org. alkoxide base in this solvent. In fact, formation of acetylide intermediates has been proposed by Ishikawa and co-workers in their studies of the alkynylation of ketones. 13 Screening of various hydroxides and alkoxides confirmed this hypothesis, revealing that anhydrous sodium, potassium, cesium hydroxides, and aqueous tetramethylammonium and benzyltrimethylammonium hydroxides catalyze formation of 1,5-diarylsubstituted-1H-1,2,3-triazoles in DMSO at room temperature (Table 1). NIH Public AccessDry DMSO and less nucleophilic bases such as potassium tert-butoxide can also be used to minimize hydrolysis of substrates which contain base-sensitive functionalities. In many cases, the desired products precipitated upon addition of 5-20× volume of ice-cold water and were isolated by simple filtration. Reactions in DMSO afforded higher isolated yield than in DMF on larger scale and at higher concentration. Although tetraalkylammonium hydroxides resulted in the slightly diminished yield of the product compared to powdered KOH, the shorter reaction time and the experimental convenience of using aqueous base solutions make tetraalkylammonium hydroxides advantageous catalysts for practical reasons.While o...

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confidence: 99%

Transition-Metal-Free Catalytic Synthesis of 1,5-Diaryl-1,2,3-triazoles

et al. 2010

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“…5 Reaction products, namely 1,2,3-triazoles, not only display a wide range of biological activities 6 but are prone to more or less facile transformations depending on the substitution pattern. 7 Cycloaddition of azides to terminal alkynes catalysed by copper clusters has been reported recently. 8 In this paper, we substantially broaden the scope of the investigation by isolating and thoroughly characterising the NPs (including behaviour to air).…”

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confidence: 99%

Cu/Cu-oxide nanoparticles as catalyst in the “click” azide–alkyne cycloaddition

et al. 2006

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“…Because of the formation of a mixture of 1,2‐diaminoethene 5 with amidine 6 in the reactions of β‐(1,2,3‐triazol‐5‐yl)enamines with TsN 3 , we assume that the formation of 5 also started from intermediate triazoline 7 . The concerted mechanism proposed by Contini and Erba8a for the transformation of morpholino‐dihydrotriazolines into azacycloalkenemonosulfonyl diamines looks hardly possible for the reactions of enamines of type 1 involving the shift of a dialkylamino group, which should have a higher activation barrier than the shift of an aromatic azolyl radical 8b. Therefore we propose that the second step for the formation of compounds 5 involves the elimination of dinitrogen from triazolines 7 to form aziridines 9 .…”

Section: Resultsmentioning

confidence: 78%

“…Clearly, the first step in all the reactions is the formation of nonaromatic 4,5‐dihydro‐1,2,3‐triazolines 7 . This type of process is well documented 6c,16. Scheme illustrates the formation of different kinds of follow‐up products depending on the specific modes [ A , B , C ( I, II ), and D ] of stabilization of triazolines 7 .…”

Section: Resultsmentioning

confidence: 87%

Reactions of β‐Azolylenamines with Sulfonyl Azides as an Approach to N‐Unsubstituted 1,2,3‐Triazoles and Ethene‐1,2‐diamines

et al. 2014

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The reactions of β‐azolylenamines 1 with sulfonyl azides 2 in acetonitrile furnished 1H‐4‐(azol‐5‐yl)‐1,2,3‐triazoles 3 in yields of 52–93 %. β‐Benzoylenaminones and β‐nitroenamine of type 1 also reacted with tosyl azide to form the same type of products 3, proving the generality and efficiency of the method for the synthesis of N‐unsubstituted 1,2,3‐triazoles. On the other hand, the reactions of 3‐(1‐aryl‐1,2,3‐triazol‐5‐yl)enamines with tosyl azide in the absence of a solvent afforded a mixture of (E)‐1‐dimethylamino‐2‐tosylaminoethenes 5 and N,N‐dimethyl‐N′‐tosylformamidine 6 in yields of 40–50 and 20 %, respectively. The formation of a variety of compounds from the reactions of enamines 1 with sulfonyl azides 2 is rationalized by the various possible transformations of the intermediate 5‐dimethylamino‐1,2,3‐triazolines 7.

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1,3‐Dipolar Cycloaddition Reactions of Organic Azides with Morpholinobuta‐1,3‐dienes and with an α‐Ethynyl‐enamine

Cited by 33 publications

References 26 publications

Transition-Metal-Free Catalytic Synthesis of 1,5-Diaryl-1,2,3-triazoles

Transition-Metal-Free Catalytic Synthesis of 1,5-Diaryl-1,2,3-triazoles

Cu/Cu-oxide nanoparticles as catalyst in the “click” azide–alkyne cycloaddition

Reactions of β‐Azolylenamines with Sulfonyl Azides as an Approach to N‐Unsubstituted 1,2,3‐Triazoles and Ethene‐1,2‐diamines

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