New Cleavage of the Azirine Ring by Single Electron Transfer: The Synthesis of 2H-Imidazoles, Pyridazines and Pyrrolines

Auricchio, S.; Grassi, Simona; Malpezzi, Luciana; Sartori, Attilio Sarzi; Truscello, Ada

doi:10.1002/1099-0690(200103)2001:6<1183::aid-ejoc1183>3.0.co;2-g

Cited by 32 publications

(14 citation statements)

References 16 publications

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“…Since the energy differences between the oxidation states of copper are narrow and other ring opening reactions of 2H ‐azirines are known to furnish both radical and ionic intermediates, the addition complex 12c can also be described by resonance structures of a stabilized dipole 12a and imine radical 12b . The formation of pyrazine by‐product 8 can be understood from the dipole character of structure 12a , which allows a direct dimerization yielding in pyrazine 8 (Path A, Scheme ).…”

Section: Resultsmentioning

confidence: 99%

A Copper‐Catalyzed Synthesis of Pyrroles through Photochemically Generated Acylazirines

Paternoga

Opatz

2019

Eur J Org Chem

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A synthesis of highly substituted 2,4‐diacylpyrroles through a Cu‐catalyzed dimerization of acylazirines generated in situ by a photochemical valence isomerization is described. The shown methodology allows the use of simple precursors and a readily available copper(II)‐catalyst. Since the reaction is best performed at elevated temperatures, a method to adjust the temperature of the reaction mixture during this dual light and metal‐induced process was established. Additionally, mechanistic studies of the reaction were performed in order to provide a deeper understanding of the chemistry of 2‐acylazirines.

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Section: Resultsmentioning

confidence: 99%

A Copper‐Catalyzed Synthesis of Pyrroles through Photochemically Generated Acylazirines

Paternoga

Opatz

2019

Eur J Org Chem

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“…It was found that water [37], Brønsted [44,48] and Lewis acids [40–41 43] facilitate the formation of pyrazine derivatives. 2 H -Azirines undergo ring opening on electronic excitation to give nitrile ylides [50].…”

Section: Resultsmentioning

confidence: 99%

“…Different mechanisms of dimerization were assumed, such as formation and dimerization of nitrile ylides [ 37 , 40 ], hydrolysis to α-aminoketenes followed by condensation [ 37 , 41 ], intermediate formation of metal complexes in the reaction mediated by metals [ 41 , 43 , 46 ]. It was found that water [ 37 ], Brønsted [ 44 , 48 ] and Lewis acids [ 40 – 41 43 ] facilitate the formation of pyrazine derivatives. 2 H -Azirines undergo ring opening on electronic excitation to give nitrile ylides [ 50 ].…”

Section: Resultsmentioning

confidence: 99%

Domino reactions of 2H-azirines with acylketenes from furan-2,3-diones: Competition between the formation of ortho-fused and bridged heterocyclic systems

Khlebnikov¹,

Новиков²,

Pakal’nis³

et al. 2014

Beilstein J. Org. Chem.

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Summary3-Aryl-2H-azirines react with acylketenes, generated by thermolysis of 5-arylfuran-2,3-diones, to give bridged 5,7-dioxa-1-azabicyclo[4.4.1]undeca-3,8-diene-2,10-diones and/or ortho-fused 6,6a,12,12a-tetrahydrobis[1,3]oxazino[3,2-a:3′,2′-d]pyrazine-4,10-diones. The latter compounds, with a new heterocyclic skeleton, are the result of the coupling of two molecules of azirine and two molecules of acylketene and can be prepared only from 3-aryl-2H-azirines having no electron-withdrawing groups in the aryl substituent. Calculations at the DFT B3LYP/6-31G(d) level for the various routes of bis[1,3]oxazino[3,2-a:3′,2′-d]pyrazine skeleton formation revealed a new domino reaction of 3-aryl-2H-azirines occurring in the presence of furandiones: acid-catalyzed dimerization to dihydropyrazine followed by consecutive cycloaddition of the latter to two molecules of acylketenes.

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“…The lower valent Cu(I) species might take part in the reductive ring opening of the 2H-azirine to give the imine derivative, 50 which then might be relayed to initiate Rh(III)-catalyzed ortho C-H rhodation, followed by insertion of the alkyne. In fact, the ultraviolet/visible (UV/vis) spectra for the treatment of Cu(OAc) 2 …”

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confidence: 99%

“…These experimental results indicated that both rhodium (Rh) and copper (Cu) are indispensable for inducing the ortho carbon-hydrogen bond functionalization of 2Hazirine 280 in the reaction to give product 237. The lower valent Cu(I) species might take part in the reductive ring opening of the 2H-azirine to give the imine derivative, 50 which then might be relayed to initiate Rh(III)-catalyzed ortho C-H rhodation, followed by insertion of the alkyne.…”

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confidence: 99%

Application of Organic Azides for the Synthesis of Nitrogen-Containing Molecules

Chiba¹

2011

Synlett

181

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In this account, recent advances made on the reactions of several types of organic azides, such as vinyl azides, cyclic 2-azido alcohols, a-azido carbonyl compounds, towards the synthesis of nitrogen-containing molecules are described. 1 Introduction 2 Chemistry of Vinyl Azides 2.1 Thermal [3+2]-Annulation of Vinyl Azides with 1,3-Dicarbonyl Compounds 2.2 Manganese(III)-Catalyzed Formal [3+2]-Annulation with 1,3-Dicarbonyl Compounds 2.3 Manganese(III)-Mediated/Catalyzed Formal [3+3]-Annulation with Cyclopropanols 2.4 Synthesis of Isoquinolines from a-Aryl-Substituted Vinyl Azides and Internal Alkynes by Rhodium-Copper Bimetallic Cooperation 3 Chemistry of Cyclic 2-Azido Alcohols 3.1 Manganese(III)-Catalyzed Ring Expansion of 2-Azidocyclobutanols 3.2 Palladium(II)-Catalyzed Ring Expansion of Cyclic 2-Azido Alcohols 4 Chemistry of a-Azido Carbonyl Compounds 4.1 Orthogonal Synthesis of Isoindole and Isoquinoline Derivatives 4.2 Generation of Iminylcopper Species and Their Catalytic Carbon-Carbon Bond Cleavage under an Oxygen Atmosphere 4.3 Copper(II)-Catalyzed Aerobic Synthesis of Azaspirocyclohexadienones 5 Conclusion

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New Cleavage of the Azirine Ring by Single Electron Transfer: The Synthesis of 2H-Imidazoles, Pyridazines and Pyrrolines

Cited by 32 publications

References 16 publications

A Copper‐Catalyzed Synthesis of Pyrroles through Photochemically Generated Acylazirines

A Copper‐Catalyzed Synthesis of Pyrroles through Photochemically Generated Acylazirines

Domino reactions of 2H-azirines with acylketenes from furan-2,3-diones: Competition between the formation of ortho-fused and bridged heterocyclic systems

Application of Organic Azides for the Synthesis of Nitrogen-Containing Molecules

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