Synthesis of 2,3-heterofused chromones, hetero analogues of xanthone

Asymmetric Organocatalyzed Cascade Reactions─Merging the pseudo-Halogen and Halogen Effect with Dienamine Catalysis.

Reactions of Ethyl 3-(4-Oxo-4H-chromen-3-yl)prop-2-enoates with 1,2-Binucleophiles

Chromones is a family of oxygen heterocyclic compounds whose synthetic versatility and broad spectrum of bioactive properties has been widely reported over the past decade. The increasing number of publications related to the synthesis of this heterocyclic system highlights diverse synthetic approaches, using different starting materials, with novel and efficient synthetic details, applying alternative heating conditions, that provides a huge number of polyfunctionalized 4 H -chromen-4-one derivatives. The purpose of this chapter is to present a comprehensive survey of the methodologies developed for the synthesis of 2,3-unsubstituted, 2- and 3-substituted and 2,3-disubstituted 4 H -chromen-4-ones, focusing on the literature since 2012, in nearly 450 publications. 

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Recent advances in the synthesis of 4H-chromen-4-ones (2012 − 2021)

Synthesis of 4,4a-Dihydroxanthone Derivatives Containing Ester and Nitrile Groups

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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Vyacheslav Ya. Sosnovskikh

Papers

Synthesis and Reactivity of Electron-Deficient 3-Vinylchromones