Efficient Synthesis of Fluorescent Coumarins and Phosphorous-Containing Coumarin-Type Heterocycles via Palladium Catalyzed Cross-Coupling Reactions

Quantum-chemical calculations on the spectral properties of some aryl substituted 3- phosphonocoumarins were performed, and the effect of the substituents in the aryl moiety was evaluated. The structures possessing promising fluorescent properties were successfully synthesized via Suzuki and Sonogashira cross-coupling. The synthetic protocol was also applied for the phosphorous chemoisomer of 3-phosphonocoumarin, 1,2-benzoxaphosphorin, and their carboxylate analogues. The optical properties of the arylated and alkynylated products were experimentally determined. The obtained quantum-chemical and experimental results give the possibility for a fine tuning of the optical properties of phosphorous-containing coumarin systems by altering the substituent at its C-6 position

The Antioxidant Activity of New Coumarin Derivatives

The antioxidant activity of two synthesized coumarins namely, N-(4,7-dioxo-2- phenyl-1,3-oxazepin-3(2H,4H,7H)-yl)-2-(2-oxo-2H-chromen-4-yloxy)acetamide 5 and N-(4-oxo-2-phenylthiazolidin-3-yl)-2-(2-oxo-2H-chromen-4-yloxy)acetamide 6 were studied with the DPPH, hydrogen peroxide and nitric oxide radical methods and compared with the known antioxidant ascorbic acid. Compounds 5 and 6 were synthesized in a good yield from the addition reaction of maleic anhydride or mercaptoacetic acid to compound 4, namely N′-benzylidene-2-(2-oxo-2H-chromen-4-yloxy)acetohydrazide. Compound 4 was synthesized by the condensation of compound 3, namely 2-(2-oxo-2H-chromen-4-yloxy) acetohydrazide, with benzaldehyde. Compound 3, however, was synthesized from the addition of hydrazine to compound 2, namely ethyl 2-(2-oxo-2H-chromen-4-yloxy)acetate, which was synthesized from the reaction of ethyl bromoacetate with 4-hydroxycoumarin 1. Structures for the synthesized coumarins 2–6 are proposed on the basis of spectroscopic evidence

Regio- and Stereoselective [2+2] Photodimerization of 3-Substituted 2-Alkoxy-2-oxo-2H-1,2-benzoxaphosphorines

Diethyl 1,2-benzoxaphosphorine-3-carboxylates 5 undergo a regio- and stereoselective [2+2] photodimerization reaction in methanol solution under the action of sunlight, giving in all cases the corresponding anti head-to-tail dimers 6 and 7. Concerning the stereogenic P atom, the photodimerization is also stereoselective, and the centrosymmetric stereoisomer 6 predominates over the non symmetric P-epimer 7

Synthesis and applications of coumarin derivatives

During the last few decades the interest in the synthesis and investigation of different coumarin derivatives and analogues has vastly increased mostly due to their multidisciplinary application in organic synthesis, agrochemistry, medicine, laser technologies, and etc. The object of our investigations is concerned on the chemical behaviors of these compounds because they are good acceptors in reactions with nucleophillic reagents, they can be used as dienophiles in Diels-Alder reaction, 1,3-bipolar cycloaddition reactions etc. The combination of coumarin structure and phosphono moiety assumes a biological activity, which can be a result of each of both units as well as a blend of both. It is clear that coumarins can be used as ligands in complexes with variety metal ions. Another aspect about coumarins which is of great interest for us is the possible photochemical properties of these compounds.Here we report reactions of cycloaddition and new rearrangement reaction resulting in potential biologically active derivatives

Regio- and Stereoselective [2+2] Photodimerization of 3-Substituted 2-Alkoxy-2-oxo-2H-1,2-benzoxaphosphorines

Diethyl 1,2-benzoxaphosphorine-3-carboxylates 5 undergo a regio- and stereoselective [2+2] photodimerization reaction in methanol solution under the action of sunlight, giving in all cases the corresponding anti head-to-tail dimers 6 and 7. Concerning the stereogenic P atom, the photodimerization is also stereoselective, and the centrosymmetric stereoisomer 6 predominates over the non symmetric P-epimer 7

Theoretical and Experimental Local Reactivity Parameters of3‑Substituted Coumarin Derivatives

International audienceLocal reactivity descriptors, such as atomic charges, atomic electrostatic potential andatomic Fukui indices were computed for a series of 3-substituted coumarin (2-oxo-2H-1-benzopyran)derivatives, using density functional theory (DFT) and Möller−Plesset methods (MP2). The variationof those properties as a function of the substituents was compared with the variation of the measuredXPS binding energies. The atomic electrostatic potentials and XPS binding energies serves as indicatorsof the electrophilicity of a given center within a molecule, while the atomic Fukui indices describe itsdegree of electronic localization, known as atomic softness. The correlation between those theoreticaland experimental properties allowed us to follow the effect of electron withdrawing substituents on theelectrophilicity of a given atomic center. The Fukui indices provided additional information about thesoftening/hardening of the center of interest due to presence of different substituents to the coumarin system. On the basis ofthese analysis, the 1,2-addition would be favored for 3-acetyl, 3-phosphono, and 7-diethylamino substituents, while 3-carboxyl, 3-ethoxycarbonyl, and 3-nitro substituent would favor 1,4-addition. The substituted coumarins would preferably react with softnucleophiles at position 2 and with hard nucleophiles at position 4