Cascade reactions between 2-substituted-3-(4-oxo-4H-chromen-3-yl)acrylonitriles with benzylamine and p-toluidine

“…Template for SynOpen Thieme It is well known that the reactivity of the pyrone ring in chromones with respect to nucleophiles increases under the influence of an electron-withdrawing substituent at the 3position, but it was difficult to foresee that the presence of a cyano group at the exo-double bond would lead to a change in the direction of the reaction with amines. Indeed, it was shown in the work of Ibrahim and Badran 43 that chromones 2b and 11 react with benzylamine and p-toluidine to form compounds 43-46, of which pairs 43/45 and 44/46 are ring-chain isomers (Scheme 22). As in all previous cases, the reaction begins with an attack by the amino group at position 2.…”

Section: Synopen Reviewmentioning

confidence: 99%

Synthesis and Reactivity of Electron-Deficient 3-Vinylchromones

Sosnovskikh¹

2021

SynOpen

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The literature data on the methods of synthesis and reactivity of electron-deficient 3-vinylchromones containing electron-withdrawing groups at the exo-cyclic double bond are summarized and systematized for the first time. The main methods for obtaining these compounds are Knoevenagel condensation, Wittig reaction, and palladium-catalyzed cross-couplings. The most important chemical properties are transformations under the action of mono- and dinucleophiles, ambiphilic cyclizations, and cycloaddition reactions. The cross-conjugated and polyelectrophilic dienone system in 3-vinylchromones provides their high reactivity and makes these compounds valuable building blocks for the preparation of more complex heterocyclic systems. Chemical transformations of 3-vinylchromones usually begin with an attack of the C-2 atom and are accompanied by the opening of the pyrone ring followed by recyclization, in which the carbonyl group of chromone, an exo-double bond or a substituent at it can take part. The mechanisms of the reactions are discussed, the conditions for their implementation and the yields of the resulting products are indicated. This review focuses on an analysis and generalization of the knowledge that has accumulated on the chemistry of electron-deficient 3-vinylchromones, mostly over the past 15 years.

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“…12 3-Substituted chromones have variable electron deficient centers and represent active substrates toward nucleophilic reagents producing numerous heterocyclic compounds. 13 In our previous work, 14 the chemical transformations of the simple condensation products derived from 3-formylchromone (1a-d) (Figure 1) was studied towards some nitrogen nucleophiles namely benzylamine and p-toluidine giving either 2-iminopyranes or pyrano [3,2-c]chromenes. Also, reaction of compounds 1b and 1d was investigated towards some bi-nitrogen nucleophiles appearing different behavior depending on the solvent used.…”

Section: Introductionmentioning

confidence: 99%

Chemical Reactivity of 1H-Benzimidazol-2-ylacetonitrile and Dimedone toward Simple Condensates Derived from 3-Formylchromone

Ibrahim¹

2022

HETEROCYCLES

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The chemical reactivity of 1H-benzimidazol-2-ylacetonitrile and dimedone was investigated towards some simple condensates (1a-d and 2a-c) obtained from condensation reaction of 3-formylchromone with some active methylene compounds. Mainly, the used nucleophiles undergo nucleophilic addition at the olefinic carbon with concomitant cycloaddition or cyclocondensation. Chromonylacrylonitrile 1a reacted with 1H-benzimidazol-2-ylacetonitrile through γ-pyrone ring opening followed by cyclocondensation giving pyrido[1,2-a]benzimidazole derivative 5. The simple condensates 2b and 2c showed similar behavior towards 1H-benzimidazol-2-ylacetonitrile and dimedone leading to the same products which are identical with those obtained from 3-formylchromone with the same reagents. Structures of the new synthesized products were established based on elemental analysis and spectral data.

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Cascade reactions between 2-substituted-3-(4-oxo-4H-chromen-3-yl)acrylonitriles with benzylamine and p-toluidine

Cited by 6 publications

References 33 publications

Unorthodox synthesis, biological activity and DFT studies of novel and multifunctionalized naphthoxocine derivatives

Unorthodox synthesis, biological activity and DFT studies of novel and multifunctionalized naphthoxocine derivatives

Synthesis and Reactivity of Electron-Deficient 3-Vinylchromones

Chemical Reactivity of 1H-Benzimidazol-2-ylacetonitrile and Dimedone toward Simple Condensates Derived from 3-Formylchromone

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