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Synthesis, Structure and Reactivity of Cyclopenta-annulated 1,2,3,4-Tetrazines

Mackert, Peter J. ; Hafner, Klaus ; Nimmerfroh, Norbert ; Banert, Klaus (1994)
Synthesis, Structure and Reactivity of Cyclopenta-annulated 1,2,3,4-Tetrazines.
In: Chemische Berichte, 127 (8)
doi: 10.1002/cber.19941270822
Artikel, Bibliographie

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Kurzbeschreibung (Abstract)

The 2-aryl-2H-cyclopenta[e]-1,2,3,4-tetrazines 3a-n are formed by coupling of the diazocyclopentadienes 1a and 1b with arenediazonium salts and subsequent reversible electrocyclization of the primary coupling products 2a-n. From the solutions of the equilibrium mixtures of 2a ⇌ 3a - 2n ⇌ 3n the tetrazines 3a-d, h-k and the arylazo-diazocyclopentadienes 2e-g and 21-n crystallize. The 2-methyl-2H-cyclopenta[e]-1,2,3,4-tetrazines 3o and 3p are obtained by addition of methyllithium to 1a and 1b followed by a diazo transfer reaction and cyclization. In solutions of 3o and 3p the ring-opened isomers 2o and 2p could not be detected. X-ray analyses of 3h and 3p prove their bicyclic planar geometry in the solid state. ¹⁵N-NMR and temperature-dependent ¹H-NMR spectroscopy have enabled a detailed study of the reversible ring closure reaction in the case of 2d ⇌ 3d. Reaction of 2-phenyl-2H-cyclopenta[e]-1,2,3,4-tetrazine (3b) with tetrafluoroboric acid results in the formation of the protonated monocyclic salt 4. Furthermore 3b undergoes electrophilic substitution reactions preferably at C-7, as demonstrated by bromination, formylation, and trifluoroacetylation. Photolysis of solutions of 2i/3i, 2k/3k, and 21/31 leads to the ketene imines 11a-c. The structure of 11c has been determined by X-ray crystallography.

Typ des Eintrags: Artikel
Erschienen: 1994
Autor(en): Mackert, Peter J. ; Hafner, Klaus ; Nimmerfroh, Norbert ; Banert, Klaus
Art des Eintrags: Bibliographie
Titel: Synthesis, Structure and Reactivity of Cyclopenta-annulated 1,2,3,4-Tetrazines
Sprache: Englisch
Publikationsjahr: 1994
Ort: Darmstadt
Verlag: Wiley
Titel der Zeitschrift, Zeitung oder Schriftenreihe: Chemische Berichte
Jahrgang/Volume einer Zeitschrift: 127
(Heft-)Nummer: 8
DOI: 10.1002/cber.19941270822
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Kurzbeschreibung (Abstract):

The 2-aryl-2H-cyclopenta[e]-1,2,3,4-tetrazines 3a-n are formed by coupling of the diazocyclopentadienes 1a and 1b with arenediazonium salts and subsequent reversible electrocyclization of the primary coupling products 2a-n. From the solutions of the equilibrium mixtures of 2a ⇌ 3a - 2n ⇌ 3n the tetrazines 3a-d, h-k and the arylazo-diazocyclopentadienes 2e-g and 21-n crystallize. The 2-methyl-2H-cyclopenta[e]-1,2,3,4-tetrazines 3o and 3p are obtained by addition of methyllithium to 1a and 1b followed by a diazo transfer reaction and cyclization. In solutions of 3o and 3p the ring-opened isomers 2o and 2p could not be detected. X-ray analyses of 3h and 3p prove their bicyclic planar geometry in the solid state. ¹⁵N-NMR and temperature-dependent ¹H-NMR spectroscopy have enabled a detailed study of the reversible ring closure reaction in the case of 2d ⇌ 3d. Reaction of 2-phenyl-2H-cyclopenta[e]-1,2,3,4-tetrazine (3b) with tetrafluoroboric acid results in the formation of the protonated monocyclic salt 4. Furthermore 3b undergoes electrophilic substitution reactions preferably at C-7, as demonstrated by bromination, formylation, and trifluoroacetylation. Photolysis of solutions of 2i/3i, 2k/3k, and 21/31 leads to the ketene imines 11a-c. The structure of 11c has been determined by X-ray crystallography.

Sachgruppe der Dewey Dezimalklassifikatin (DDC): 500 Naturwissenschaften und Mathematik > 540 Chemie
Fachbereich(e)/-gebiet(e): 07 Fachbereich Chemie
07 Fachbereich Chemie > Clemens-Schöpf-Institut
07 Fachbereich Chemie > Clemens-Schöpf-Institut > Fachgebiet Organische Chemie
Hinterlegungsdatum: 02 Aug 2024 12:51
Letzte Änderung: 02 Aug 2024 12:51
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