A simple method for the synthesis of some 1,2-diazocines

Haddadin, Makhluf J.; Agha, Bushra J.; SALKA, M. S.

doi:10.1016/s0040-4039(01)81235-1

Cited by 27 publications

(8 citation statements)

References 5 publications

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“…For example, in previous work we reported the reactions of 3,6-diphenyl-1,2,4,5-tetrazine ( 1a ) with enolate anions as an effective method for pyridazine synthesis ( 3 ; eq 1) . However, we found that when employing the enolate of cyclobutanone, the reaction led not to a pyridazine but to a [1,2]diazocin-4-one ( 5 ; eq 2) …”

Section: Introductionmentioning

confidence: 89%

A Novel Route to Fully Substituted 1H-Pyrazoles

et al. 2005

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Section: Introductionmentioning

confidence: 89%

A Novel Route to Fully Substituted 1H-Pyrazoles

et al. 2005

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“…Besides normal aromatic nucleophilic substitution at carbons, the S N (ANRORC) mechanism becomes operative, for example, in the Chichibabin hydrazination of monosubstituted s -tetrazines . Based on the IEDDA reaction of s -tetrazine with four-membered dienophiles as the initial chemical act followed by subsequent small ring expansion, interesting examples of synthesized eight-membered heterocycles, such as diazocine and triazocine, have been reported. However, four-membered thietanones reacting with s -tetrazines led to pyrazol-4-ols instead of the expected thiadiazocine system by a nonobvious cascade of reactions, including cycloaddition, recyclization, and sulfur extrusion.…”

Section: Introductionmentioning

confidence: 99%

Three-Component Reaction of 3,3-Difluorocyclopropenes, s-Tetrazines, and (benzo) Pyridines

Nechaev¹,

Cherkaev

Boev³

et al. 2020

J. Org. Chem.

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A new three-component reaction leading to 1-α-(pyridyl-2-[1,2,4]triazolyl)-2-alkyl-ethanones has been discovered while studying the reactivity of monosubstituted 3,3-difluorocyclopropenes in an inverse electronic demand Diels−Alder (IEDDA) cycloaddition−cycloreversion sequence with s-tetrazines. The reaction involving the above-mentioned reactants and (benzo)pyridine as a third component results in a complex transformation proceeding in mild conditions in a stoichiometric ratio of reactants and has high functional group tolerance (phenols, amides, ethers, carboxylic acids, ketones, and acrylic esters). As a result, simple pyridines are selectively functionalized at the α-position in good isolated yields. The reaction mechanism includes a rare azaphilic [4 + 2]cycloaddition step between s-tetrazine and intermediate 1-hydroxyindolizine, suggested after byproduct identification and tracked with a deuterium label. To date, it is only the third known example of skewed azaphilic cycloaddition of tetrazine. The reaction is truly three-component and cannot be effectively performed stepwise.

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“…An unexpected route to 1,2-diazocinones (herein referred to as diazocinones) was uncovered two decades ago during the course of studies on the formation of pyridazines from tetrazines and various enolate species (Scheme ). , A follow-up study then examined the conformational properties of several analogues of these systems . These reactions, like the others mentioned above, are quite interesting from a mechanistic standpoint.…”

Section: Introductionmentioning

confidence: 99%

Mechanisms for Formation of Diazocinones, Pyridazines, and Pyrazolines from Tetrazines—Oxyanion-Accelerated Pericyclic Cascades?

2009

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A computational approach is utilized to study the diazocinone- and pyridazine-forming cascade reactions resulting from the reaction of 1,2,4,5-tetrazines with cyclic enolates. Many of the proposed reaction steps can be formulated as oxyanion-accelerated pericyclic processes. In examining these, a unique stepwise version of a formal (4 + 2) cycloaddition/(4 + 2) cycloreversion was discovered. For the key ring-opening step in these cascades, theoretical evidence for two distinct processes is reported. Of these two possibilities, an allowed six-electron electrocyclic ring-opening is predicted to be highly favored both kinetically and thermodynamically. Evidence for an unexpected oxyanion-accelerated 1,2-sigmatropic shift was also found for certain systems, leading to the theoretical prediction that seven- and eight-membered ring-fused pyrazoline systems could be formed experimentally under conditions similar to those for diazocinone and pyridazine formation.

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A simple method for the synthesis of some 1,2-diazocines

Cited by 27 publications

References 5 publications

A Novel Route to Fully Substituted 1H-Pyrazoles

A Novel Route to Fully Substituted 1H-Pyrazoles

Three-Component Reaction of 3,3-Difluorocyclopropenes, s-Tetrazines, and (benzo) Pyridines

Mechanisms for Formation of Diazocinones, Pyridazines, and Pyrazolines from Tetrazines—Oxyanion-Accelerated Pericyclic Cascades?

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