Über 1,4‐Dihydro‐1,2,4,5‐tetrazine

Neugebauer, Franz A.; Kriger, Claus; Fischer, Hans; Siegel, Rolf

doi:10.1002/cber.19831160617

Cited by 37 publications

(15 citation statements)

References 18 publications

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“…fur C,H,, CIN,O,S (395,81): C 54,61,H 5,60,C1 8,95,N 10,61,0 l2,12,S 8,lO;gef. : C 54,0,H 5,6,CI 9,2,N 10,6, 0 12,3, S 8,2.…”

Section: Schema 4 4c 2cmentioning

confidence: 98%

“…Die 1 ,CDihydro-1,2,4,5-tetrazine lassen sich in zwei Schritten zur Tetrazin-Stufe oxidieren. Seit bald 20 Jahren ist bekannt, dass durch milde Oxidation von 1,4-Dihydro-1,2,4,5-tetrazinen und substituierten Derivaten stabile, isolierbare Radikal-Kationen erzeugt werden konnen [2-61; es wurden auch ESR-Spektren dieser Radikal-Kationen aufgenommen [2] 131 [6]. Cyclovoltammetrische Messungen des Oxidationsverhaltens einiger symmetrisch substituierter 1,4-Dihydro-1, 2,4,5- Reaktion der im Produkt 2 rnit * bezeichneten N-Atome rnit den C-Zentren ** des jeweils anderen Heterocyclus.…”

unclassified

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Neue Heterocyclen: Über Tetrazinodi(heteroarene). Synthese und Struktur

Eichenberger

Balli

1986

Helvetica Chimica Acta

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Novel Heterocycles: Tetrazinodi(heteroarenes), Synthesis and StructureA series of 7 new symmetric tetrazinodi(heter0arenes) is obtained in a two-step synthesis by N-aminating heterocyclic compounds substituted with a leaving group and by treating the latter with an organic or inorganic base. The new compounds are characterized, and the postulated structures are confirmed by X-ray analysis of a representative example. 1.Einleitung. -Im Arbeitskreis von Huenig wurde systematisch das Redoxverhalten zahlreicher organischer Verbindungen untersucht, welche in der Lage sind, ein Elektronenpaar in zwei getrennten Einelektronenschritten aufzunehmen oder abzugeben [ 11. Zwischen der reduzierten Form RED und der oxydierten Form OX liegt die 'SemichinonForm' SEM, welche ein ungepaartes Elektron besitzt, also radikalischen Charakter aufweist. Die thermodynamische Stabilitit dieser Radikale wird mit Gleichung I und 2 beschrieben (Schema I ) . Die Radikalbildungskonstante KsEM ist um so grosser, je weiter die beiden elektrochemischen Halbstufenpotentiale E, und E2 der beiden Einelektronenschritte auseinanderliegen. Die Messung von E, und E2 mittels elektrochemischer Metho-

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“…fur C,H,, CIN,O,S (395,81): C 54,61,H 5,60,C1 8,95,N 10,61,0 l2,12,S 8,lO;gef. : C 54,0,H 5,6,CI 9,2,N 10,6, 0 12,3, S 8,2.…”

Section: Schema 4 4c 2cmentioning

confidence: 98%

unclassified

Neue Heterocyclen: Über Tetrazinodi(heteroarene). Synthese und Struktur

Eichenberger

Balli

1986

Helvetica Chimica Acta

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“…15 ) The 1,4-dihydro-1,2,4,5-tetrazines adopt a flattened 3,6 B conformation with the 3-and 6-substituents in bowsprit position [32]. A 1,2-dihydro-1,2,4,5-tetrazine structure is excluded, since 1,2-dihydro-1,2,4,5tetrazines rearrange readily to the more-stable 1,4-dihydro-1,2,4,5-tetrazines [33].…”

Section: And Of Menhmentioning

confidence: 99%

Glycosylidene Carbenes. Part 31

Bernet

Mangholz

Briner

et al. 2003

Helvetica Chimica Acta

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Dedicated to Professor Jack D. Dunitz on the occasion of his 80th birthdayThe diastereoselectivity of the addition of NH 3 and MeNH 2 to glyconolactone oxime sulfonates and the structures of the resulting N-unsubstituted and N-methylated glycosylidene diaziridines wereThe 15 N-labelled glucono-and galactono-1,5-lactone oxime mesylates 1* and 9* add NH 3 mostly axially (> 3 : 1; Scheme 4), while the 15 N-labelled mannono-1,5-lactone oxime sulfonate 19* adds NH 3 mostly equatorially (9 : 1; Scheme 7). The 15 N-labelled mannono-1,4-lactone oxime sulfonate 30* adds NH 3 mostly from the exo side (> 4 :1; Scheme 9). The configuration of the N-methylated pyranosylidene diaziridines 17, 18, 28, and 29 suggests that MeNH 2 adds to 1, 9, 19, and 23 mostly to exclusively from the equatorial direction (> 7 : 3; Schemes 5 and 8). The mannono-1,4-lactone oxime sulfonate 30 adds MeNH 2 mostly from the exo side (85 : 15; Scheme 10), while the ribo analogue 37 adds MeNH 2 mostly from the endo side (4 : 1; Scheme 10). Analysis of the preferred and of the reactive conformers of the tetrahedral intermediates suggests that the addition of the amine to lactone oxime sulfonates is kinetically controlled. The diastereoselectivity of the diaziridine formation is rationalized as the result of the competing influences of intramolecular H-bonding during addition of the amines, steric interactions (addition of MeNH 2 ), and the kinetic anomeric effect.The diaziridines obtained from 2,3,5-tri-O-benzyl-d-ribono-and -d-arabinono-1,4-lactone oxime methanesulfonate (42 and 48; Scheme 11) decomposed readily to mixtures of 1,4-dihydro-1,2,4,5-tetrazines, pentono-1,4-lactones, and pentonamides.The N-unsubstituted gluco-and galactopyranosylidene diaziridines 2, 4, 6, 8, and 10 are mixtures of two trans-substituted isomers (S/R ca. 19 :1, Scheme 2). The main, (S,S)-configured isomers S are stabilised by a weak intramolecular H-bond from the pseudoaxial NH to ROÀC(2). The diaziridines 12, derived from GlcNAc, cannot form such a H-bond; the (R,R)-isomer dominates (R/S 85 : 15; Scheme 3). The 2,3-di-O-benzyld-mannopyranosylidene diaziridines 20 and 22 adopt a 4 C 1 conformation, which does not allow an intramolecular H-bond; they are nearly 1 : 1 mixtures of R and S diastereoisomers, whereas the O H 5 conformation of the 2,3:5,6-di-O-isopropylidene-d-mannopyranosylidene diaziridines 24 is compatible with a weak H-bond from the equatorial NH to OÀC(2); the (R,R)-isomer is favoured (R/S ! 7 : 3; Scheme 6). The mannofuranosylidene diaziridine 31 completely prefers the (R,R)-configuration (Scheme 9).

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“…1,2,4,5-tetrazines can also be readily reduced to 3,6-dihydro derivatives. 10 There has been only a little work done on the unsubstituted parent tetrazine due to the difficulties with its synthesis and stability. In contrast the chemistry of 3,6-subsituted tetrazines and its derivatives has been studied quite extensively.…”

Section: Introductionmentioning

confidence: 99%