Out of cross-conjugation: the unexpected structure of tetrazinones

Bényei, Attila; Stirling, András; Bostai, Beatrix; Lőrincz, Krisztián; Kotschy, András

doi:10.1039/c4ra05616g

“…1(c)). 29 In this paper, we propose a synthetic method for the unique tetrazinone zwitterion 6-oxo-3-(1,2,4,5-substituted-1H-imidazol-3-ium-3-yl)-3,6-dihydro-1,2,4,5-tetrazin-3-ide via the reaction of 3,6-dichloro-1,2,4,5-tetrazine with substituted imidazole in the solution of tetrahydrofuran containing a trace amount of water. Spectroscopic data and X-ray diffraction studies indicate that the new tetrazinone is a quinoidal-like structure with a carbonyl group at position 3 and a substituted imidazole at position 6, with a C-N bond between tetrazine and imidazole rings (Fig.…”

Section: Introductionmentioning

confidence: 99%

A new class of unique quinoidal-like imidazoliumyl tetrazinides: synthesis, structure, and mechanism

Geng,

Sun,

Zhang

et al. 2024

New J. Chem.

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Head‐to‐Tail Dimerization of N‐Heterocyclic Diazoolefins

Varava

¹

,

Wong

²

,

Dong

³

et al. 2023

Angewandte Chemie

0

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The head-to-tail dimerization of N-heterocyclic diazoolefins is described. The products of these formal (3+3) cycloaddition reactions are strongly reducing quinoidal tetrazines. Oxidation of the tetrazines occurs in a stepwise fashion, and we were able to isolate a stable radical cation and diamagnetic dications. The latter are also accessible by oxidative dimerization of diazoolefins.Diazoalkanes undergo (2+3) cycloaddition reactions with a large variety of dipolarophiles (Scheme 1a). [1] First evidence for such a transformation was provided in 1888 by Buchner. [2] He noted that the reaction of methyl diazoacetate with dimethyl fumaric acid gives a well-defined addition product. Soon after, von Pechmann investigated similar reactions with diazomethane. [3] Today, 1,3-dipolar cycloaddition reactions (Huisgen reactions) [4] between diazoalkanes and dipolarophiles represent an indispensable tool in heterocyclic chemistry. [1] In contrast to the rich chemistry of diazoalkanes, there are only limited studies with diazoolefins. [5][6][7][8][9] A key problem for experimental work is the low stability of most diazoolefins, as they tend to lose dinitrogen, even at low temperatures. However, it could be established that diazoolefins are also able to undergo 1,3-dipolar cycloaddition reactions (Scheme 1b). [6,7]

show abstract

Head‐to‐Tail Dimerization of N‐Heterocyclic Diazoolefins

Varava

¹

,

Wong

²

,

Dong

³

et al. 2023

View full text Add to dashboard Cite

The head-to-tail dimerization of N-heterocyclic diazoolefins is described. The products of these formal (3+3) cycloaddition reactions are strongly reducing quinoidal tetrazines. Oxidation of the tetrazines occurs in a stepwise fashion, and we were able to isolate a stable radical cation and diamagnetic dications. The latter are also accessible by oxidative dimerization of diazoolefins.Diazoalkanes undergo (2+3) cycloaddition reactions with a large variety of dipolarophiles (Scheme 1a). [1] First evidence for such a transformation was provided in 1888 by Buchner. [2] He noted that the reaction of methyl diazoacetate with dimethyl fumaric acid gives a well-defined addition product. Soon after, von Pechmann investigated similar reactions with diazomethane. [3] Today, 1,3-dipolar cycloaddition reactions (Huisgen reactions) [4] between diazoalkanes and dipolarophiles represent an indispensable tool in heterocyclic chemistry. [1] In contrast to the rich chemistry of diazoalkanes, there are only limited studies with diazoolefins. [5][6][7][8][9] A key problem for experimental work is the low stability of most diazoolefins, as they tend to lose dinitrogen, even at low temperatures. However, it could be established that diazoolefins are also able to undergo 1,3-dipolar cycloaddition reactions (Scheme 1b). [6,7]

show abstract

Out of cross-conjugation: the unexpected structure of tetrazinones

Abstract: Combined experimental and theoretical investigations helped to elucidate the mechanisms responsible for the unique structural and electronic properties of NHC-substituted tetrazinone compounds.

Cited by 3 publications

References 50 publications

A new class of unique quinoidal-like imidazoliumyl tetrazinides: synthesis, structure, and mechanism

A new class of unique quinoidal-like imidazoliumyl tetrazinides: synthesis, structure, and mechanism

Head‐to‐Tail Dimerization of N‐Heterocyclic Diazoolefins

Head‐to‐Tail Dimerization of N‐Heterocyclic Diazoolefins

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