Organobase catalyzed 1,4-conjugate addition of 4-hydroxycoumarin on chalcones: Synthesis, NMR and single-crystal X-ray diffraction studies of novel warfarin analogues

Synthesis of cobalt- ferrite and zinc oxide metal nanoparticles based-bentonite using SDS and their investigation as catalysts in synthesis of benzylbarbiturocoumarins

In this research, a suitable and efficient CoFe2O4@ZnO@Bentonite nano-catalyst was designed and synthesized by using zinc oxide (ZnO) and cobalt ferrite (CoFe2O4) nanoparticles and bentonite by microwave irradiation. Characteristics of the synthesized nanocomposite were investigated by Fourier transform infrared (FT-IR), scanning electron microscope (SEM), energy dispersive X-ray (EDX), transmission electron microscope (TEM), X-ray diffraction (XRD), Bruner- Emmett-Teller (BET) and vibrating sample magnetometer (VSM) techniques. The produced catalyst was effectively employed as a supported solid acid catalyst in mildly agitated three-component reactions involving aromatic aldehydes, 4-hydroxycoumarin, and 1,3-dimethyl-barbituric acid in a single pot to produce benzylbarbiturocoumarins. Starting materials were condensed via three C-C bond formation by CoFe2O4@ZnO@Bentonite as an efficient, recyclable, and environmentally safe nanocatalyst to obtain target products. The advantages of this method include using a natural substrate, small amounts of catalyst, aqueous media, performing reactions at ambient temperature, simple separation and purification of products, and good yields with short reaction times.

Visible-Light-Promoted Intramolecular C-O Bond Formation via Csp3-H Functionalization: A Straightforward Synthetic Route to Biorelevant Dihydrofuro[3,2-c]chromenone Derivatives

A photochemical method for the synthesis of functionalized dihydrofuro[3,2-c]chromenones via intramolecular C_sp³-H cross-dehydrogenative oxygenation within a warfarin framework has been unearthed. Advantages of this protocol include abundant sunlight or low-energy visible light as the energy source, mild reaction conditions, and avoidance of metal catalysts.

Facile and Straightforward Synthesis of Racemic Version of Substituted 3-[3-(2-Hydroxyphenyl)-3-oxo-1-arylpropyl]-4-hydroxycoumarins: Easy Access to a Series of Biorelevant Warfarin Analogues

The present communication deals with a straightforward, efficient, and green synthesis of a series of racemic version of 3-[3-(2-hydroxyphenyl)-3-oxo-1-arylpropyl]-4-hydroxycoumarins as biologically interesting warfarin analogues upon decarboxylative hydrolysis of bis-coumarin derivatives in aqueous potassium hydroxide solution. The salient features of this practical method are operational simplicity, avoidance of any organic solvents and tedious column chromatographic purification, clean reaction profiles, excellent yields, and gram-scale synthetic applicability.

Hemisynthesis of coumarin derivatives from Ammodaucus leucotrichus oil extract: organobase-catalyzed reaction, analytical study by diffusion-ordered spectroscopy NMR and differential scanning calorimetry

This paper presents an in-depth chemical and analytical study of a natural substance extracted from Ammodaucus leucotrichus Coss. & Dur and its derivatives after hemisynthesis. The analysis was performed using Diffusion-Ordered Spectroscopy (NMR DOSY) and Differential Scanning Calorimetry (DSC) as general methods. The results show an interesting chemical reactivity towards coumarin-derived bisnucleophiles (4-hydroxycoumarin and triacetic acid lactone), and products obtained by hemisynthesis of pyrano[4,3-b]pyrane derivatives following Knoevenagel condensation and Michael's addition on this natural substance with the use of 4-pyrolidinopyridine organobase as catalyst.

Synthesis of A-Type Proanthocyanidins and Their Analogues: A Comprehensive Review

Proanthocyanidins (PACs) are oligomers or polymers composed of units of flavanols. A-type PACs are a subclass of PACs characterized by the presence of at least a double linkage between two consecutive monomers of flavanol. These A-type PACs are found in some fruits and spices and possess potential health benefits as a result of their interesting biological activities, and consequently, their isolation and synthesis have given rise to great interest in the past. This review summarizes the synthetic efforts made to obtain both naturally occurring A-type PACs and their structurally simplified analogues. Most of the synthetic protocols reported involve the addition of a π-nucleophilic molecule over a molecule with two electrophilic carbons, such as a chalcone, a flavylium salt, or a flavanol derivative, among others. Synthesis of A-type PACs remains an issue at a very early stage of development compared to that of PACs with single linkages between monomers (B-type PACs), but the advances that are taking place in the last few years point to a significant development of the subject in the near future.

Organobase catalysed one-pot exo-selective synthesis of meso-spiro[cyclohexanone-pyrandione] derivatives

A facile metal-free one-pot exo-stereoselective synthesis of through two sequential organobase-catalysed 1,4-conjugate additions of pyran-2,4-diones on diarylideneacetone synthons is disclosed.