1,2,3‐Triazine, IV Synthese von 1,2,3‐Triazincarbonsäureestern

Neunhoeffer, Hans; Bopp, R. J.; Diehl, W.

doi:10.1002/jlac.199319930162

Cited by 25 publications

(14 citation statements)

References 10 publications

(1 reference statement)

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“…Igeta provided a convenient synthesis, entailing the oxidative (NaIO 4 ) ring expansion of N -aminopyrazoles, but the scope of their cycloaddition reactions remained limited. In 2011, there were only a handful of substituted monocyclic 1,2,3-triazines known at the time we initiated our efforts. − We conducted a systematic study of the reactivity of 1,2,3-triazines in inverse electron demand Diels–Alder reactions, including an examination of the impact of a C5 substituent (Figure ). The C5 substituents were found to predictably exhibit a remarkable impact on the 1,2,3-triazine cycloaddition reactivity and further enhanced their intrinsic C4/N1 cycloaddition regioselectivity.…”

Section: Heterocyclic Azadienesmentioning

confidence: 99%

Inverse Electron Demand Diels–Alder Reactions of Heterocyclic Azadienes, 1-Aza-1,3-Butadienes, Cyclopropenone Ketals, and Related Systems. A Retrospective

2019

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A summary of the investigation and applications of the inverse electron demand Diels–Alder reaction is provided that have been conducted in our laboratory over a period that now spans more than 35 years. The work, which continues to provide solutions to complex synthetic challenges, is presented in the context of more than 70 natural product total syntheses in which the reactions served as a key strategic step in the approach. The studies include the development and use of the cycloaddition reactions of heterocyclic azadienes (1,2,4,5-tetrazines; 1,2,4-, 1,3,5-, and 1,2,3-triazines; 1,2-diazines; and 1,3,4-oxadiazoles), 1-aza-1,3-butadienes, α-pyrones, and cyclopropenone ketals. Their applications illustrate the power of the methodology, often provided concise and nonobvious total syntheses of the targeted natural products, typically were extended to the synthesis of analogues that contain deep-seated structural changes in more comprehensive studies to explore or optimize their biological properties, and highlight a wealth of opportunities not yet tapped.

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Section: Heterocyclic Azadienesmentioning

confidence: 99%

Inverse Electron Demand Diels–Alder Reactions of Heterocyclic Azadienes, 1-Aza-1,3-Butadienes, Cyclopropenone Ketals, and Related Systems. A Retrospective

2019

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“…The subsequent NaIO 4 oxidative ring expansion generated the desired 1,2,3-triazines, which were purified by standard column chromatography. We previously reported the preparation of 3a , and both 3b and 3c have been synthesized previously through a similar oxidative ring expansion, although no studies of the cycloaddition reactivity of these two compounds have been disclosed. 1,2,3-Triazines 3a and 3c were further characterized by X-ray (Figure ; see also Tables S1 and S2 and Figures S1 and S2), and the significance of the X-ray of 3c is discussed below alongside rate studies quantitating the reactivities of 3a–c and related compounds…”

Section: Resultsmentioning

confidence: 99%

Reaction Scope of Methyl 1,2,3-Triazine-5-carboxylate with Amidines and the Impact of C4/C6 Substitution

Quiñones

Boger

2021

J. Org. Chem.

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A comprehensive study of the reaction scope of methyl 1,2,3-triazine-5-carboxylate (3a) with alkyl and aryl amidines is disclosed, reacting at room temperature at remarkable rates (<5 min, 0.1 M in CH3CN) nearly 10000-fold faster than that of unsubstituted 1,2,3-triazine and providing the product pyrimidines in high yields. C4 Methyl substitution of the 1,2,3-triazine (3b) had little effect on the rate of the reaction, whereas C4/C6 dimethyl substitution (3c) slowed the room-temperature reaction (<24 h, 0.25 M) but displayed an unaltered scope, providing the product pyrimidines in similarly high yields. Measured second-order rate constants of the reaction of 3a–c, the corresponding nitriles 3e and 3f, and 1,2,3-triazine itself (3d) with benzamidine and substituted derivatives quantitated the remarkable reactivity of 3a and 3e, verified the inverse electron demand nature of the reaction (Hammett ρ = −1.50 for substituted amidines, ρ = +7.9 for 5-substituted 1,2,3-triazine), and provided a quantitative measure of the impact of 4-methyl and 4,6-dimethyl substitution on the reactivity of the methyl 1,2,3-triazine-5-carboxylate and 5-cyano-1,2,3-triazine core heterocycles.

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“…The more general synthetic method to obtain various mono-, di-and tri-substituted alkyl-and aryl-triazines, besides the parent triazine 1, is by oxidation of N-aminopyrazoles 36 with lead(IV) acetate (LTA; Pb(C 2 H 3 O 2 ) 4 ), nickel peroxide or sodium perchlorate [27,48,64,66,94,95] (Scheme 20.4). The amino nitrogen is incorporated into the triazine ring as the central nitrogen N2, probably via insertion of the nitrene moiety to the NÀN bond of the pyrazole ring [72].…”

Section: From Pentacyclesmentioning

confidence: 99%