Synthesis and chemical properties of chromone-3-carboxylic acid (review)

Synthesis and Reactivity of Electron-Deficient 3-Vinylchromones

The reported methods and data for the 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 on it can take part. The mechanisms of the reactions are discussed, the conditions for their implementation are described, and the yields of the resulting products are given. 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.

1 Introduction

2 Synthesis of 3-Vinylchromones

3 Reactions with Mononucleophiles

4 Reactions with Dinucleophiles

5 Ambiphilic Cyclization

6 Cycloaddition Reactions

7 Other Reactions

8 Conclusion

Synthesis and reactivity of 3-(1-alkynyl)chromones

For the first time, the literature data on the methods of synthesis and reactivity of 3-(1-alkynyl)chromones are summarized and systematized. The main method for obtaining these compounds is the Sonogashira cross-coupling reaction of 3-halochromones with terminal acetylenes, and their most important chemical properties include the transformation into furans, reactions with dinucleophiles, ambiphilic [4+2]- and [4+3]-cyclizations, and also dimerization and mixed condensation of 2-methyl-3-(1-alkynyl)chromones due to the vinylogous methyl group. Except for the oxacyclization to furans, chemical transformations of 3-(1-alkynyl)chromones are accompanied by pyrone ring transformation, in which not only the carbonyl group but also the triple bond can participate. This significantly increases the synthetic value of these compounds and ensures the production of more complex heterocyclic systems based on them. The mechanisms of the reactions are discussed, the conditions for their implementation and the yields of the resulting products are indicated.

The bibliography includes 80 references.

Conformational & spectroscopic characterization, charge analysis and molecular docking profiles of chromone-3-carboxylic acid using a quantum hybrid computational method

The Spectroscopic profile of Chromone-3-Carboxylic Acid (abbreviated as C3CA) was examined using FT-IR, FT-Raman, UV, ¹H and ¹³C NMR techniques. The geometrical parameters and energies attained from DFT/B3LYP method with 6-311++G (d,p) basis sets calculations. The geometry of the molecule was fully optimized, vibrational spectra were calculated and assigned the fundamental vibrations on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. The XRD data obtained from the computed geometric parameters shows that there is little deviation in the structure due to the substitution of the COOH group in the molecule. Using NBO study, the delocalization of the electron and the corresponding attraction between the orbitals shows that the lone pair transition has higher stabilization energy when compared with remaining atoms. The ¹H and ¹³C NMR chemical shifts are calculated using GIAO method and the experimental chemical shifts were analysed with theoretical values which reflects better coincidence. The electronic properties, HOMO and LUMO energies, are performed with TD-DFT reproduces good with the experimental findings. Besides, frontier molecular orbitals (FMO), the high reactive nature of the molecule is identified with MEP and global reactivity descriptor analysis are performed. In addition, the molecular docking study was conducted, and results of the docking study identified the sugar phosphatase inhibitor activity of the target molecule (C3CA).