Synthesis of C3-dihydrofuran substituted coumarins via multicomponent approach

An efficient method was developed for the synthesis of dihydrofuran substituted coumarin from a one-pot, four-component reaction of 2-hydroxy aromatic aldehydes, 6-methyl, 4-hydroxy pyranone, aromatic aldehyde, and pyridinium ylide in the presence of tri-ethylamine under microwave irradiation. The reaction proceeds under solvent-free conditions to afford C3-dihydrofuran substituted coumarin in a diastereoselective manner in good yields (71–89%).     

One-pot catalyst-free synthesis of 3-heterocyclic coumarins

Research on Chemical Intermediates - 3-Heterocyclic coumarins were prepared in one-pot three-component reaction without catalyst. The mixture of salicylaldehydes, ethyl cyanoacetate, and...     

Convenient synthesis of 3-vinyl and 3-styryl coumarins

A variety of 2-hydroxy aldehydes on reaction with 3-butenoic acid afford in a one-pot reaction the corresponding 3-vinylcoumarins. As expected, extension of the delocalized π-electron system accomplished by Heck coupling reactions with aryl halides results in an increased fluorescence of the compounds whose applicability is yet to be established.     

Green chemistry approach for the synthesis of PbSnO<Subscript>3</Subscript>

We report synthesis of light-induced heterogeneous photocatalyst PbSnO₃ by green chemistry approach, using mechanochemical method. The synthesized catalyst was characterized physically by various analytical investigative techniques like UV-DRS, FTIR, XRD, SEM, EDAX, TEM, and TG. The product corresponded to average particle size of 100 nm by TEM images. Photocatalytic activity of PbSnO₃ was studied by photodegradation of Methyl blue, Indigo carmine, and Acid violet dyes under sunlight. The results indicate that the sunlight stimulates a photochemical reaction and successfully complete mineralization of Methyl blue, Indigo carmine, and Acid violet dyes. Antimicrobial activity shows that PbSnO₃ photocatalyst was found non-toxic to the environment.     

Straightforward stereoselective synthesis of polyfunctionalised cyclohexenols using a multicomponent approach

An intramolecular Ugi 5-centre-4-component reaction (U-5C-4CR) followed by a palladium-catalysed ring-opening has been employed to transform oxabicycloheptene-based β-amino acids into two families of regioisomeric polyfunctionalised cyclohexenols. The whole process is completely stereoselective and enantiomerically pure products are obtained in high overall yields.     

A novel multicomponent approach to the synthesis of 1,3-thiazolidine-2-thiones

An easy, efficient, and simple one-pot approach for the synthesis of 1,3-thiazolidine-2-thiones via multicomponent reaction is reported. The reaction of a primary amine with carbon disulfide in the presence of dibenzoylacetylene or bis(4-methyl-1-benzoyl)acetylene in a mixture of CH₂Cl₂ and H₂O after 5 h, afforded the title compound as alkene diastereomers.     

Green chemistry approach to the synthesis of N-substituted piperidones

An efficient green chemistry approach to the synthesis of N-substituted piperidones and piperidines was developed and applied to the synthesis of 1-(2-pyridinylmethyl)-piperidin-4-one, 1, a key starting material for the synthesis of LY317615, an antiangiogenic agent currently under development at Eli Lilly and Company (Chart 1).(1) The general utility of this methodology, which presents significant advantages over the classical Dieckman approach to this class of compounds, was also demonstrated by the direct synthesis of a series of substituted piperidones and piperidines, including potential dopamine D4 receptor antagonists 2 and 3, that have been evaluated in the clinic as antipsychotic agents (Chart 2).(2)     

A facile and expeditious approach for the synthesis of 2-azetidinone derivatives via a multicomponent reaction

Abstract  

New organic reactions allow chemical transformations which were previously unknown. Therefore, new reactions are important contributions to progress in the field of organic synthesis. Herein, we are reporting a simple, one-pot, efficient three-component synthesis of novel 3-chloro-4-[4-(2-oxo-2H-chromen-4-ylmethoxy)phenyl]-1-phenylazetidin-2-one derivatives using 4-(2-oxo-2H-chromen-4-ylmethoxy)benzaldehydes, anilines, and chloroacetyl chloride in the presence of triethyl amine as a catalyst under different conditions. Taking into account environmental and economic considerations, the protocol presented here has the merits of simple operation, convenient work-up, being environmentally benign, and providing good yields. The synthesized compounds were characterized by IR, ¹H NMR, ¹³C NMR, MS, and elemental analysis.     

A new approach to the chemical synthesis of keto-proteins

To increase the versatility of protein-conjugation, an orthogonal protection strategy is described, which enables the efficient synthesis of keto-proteins bearing a reactive ketone functionality using Boc, Fmoc, and chemical ligation methodologies. A 1,3-dithiolane group was used to protect the ketone function of levulinate- and pyruvate-derivatized peptides during solid-phase synthesis, acidolytic cleavage, and purification. When required, the 1,3-dithiolane group could be cleanly removed using aqueous silver or mercuric solutions to regenerate the reactive keto-protein at ambient temperature. The liberated keto-protein was chemoselectively conjugated in situ to an aminooxy-derivatized monodisperse polymer.     

A cross-metathesis approach for the synthesis of tedanolide and 13-deoxytedanolide: stereoselective synthesis of the C3-C16 segment

A unified synthetic strategy has been devised for the synthesis of both tedanolide and 13-deoxytedanolide, which involves a cross-metathesis reaction as the key step. We report herein the stereoselective synthesis of the C3-C16 segment (+)-5b and subsequent manipulation of the C12-C13 double bond leading to the preparation of both tedanolides.     

Silica-bonded S-sulfonic acid a recyclable catalyst for the synthesis of coumarins

Silica-bonded S-sulfonic acid(SBSSA) was prepared by the reaction of 3-mercaptopropylsilica(MPS) and chlorosulfonic acid in chloroform.This solid acid has been employed as a recyclable catalyst for the synthesis of coumarins from phenols andβ-ketoesters at 80℃under solvent-free conditions.     

Phosphine-catalyzed synthesis of highly functionalized coumarins

2-Styrenyl allenoates are converted into cyclopentene-fused dihydrocoumarins through phosphine-catalyzed regio- and diastereoselective [3 + 2] cycloadditions. Remarkably, changing the solvent from THF to benzene promotes the conversion of the 2-(2-nitrostyrenyl) allenoate into a tricyclic nitronate through a previously undocumented mode of phosphine catalysis. This nitronate was subjected to efficient face-, regio-, and exo-selective 1,3-dipolar cycloadditions to provide tetracyclic coumarin derivatives.     

Green one-pot multicomponent synthesis of pyrrolidinones using planetary ball milling process under solvent-free conditions

This paper presents a novel and efficient protocol for the synthesis of pyrrolidinones using catalytic loading of 1,1'-butylenebis(3-sulfo-3H-imidazol-1-ium) hydrogen sulfate as a recyclable Brönsted acid ionic liquid through ball milling process at room temperature under solvent-free conditions. The developed method provides good to excellent yields of various pyrrolidinones in environmentally friendly conditions. Furthermore, this efficient protocol displays a combination of the synthetic advantage of one-pot multicomponent reaction with ecological benefits and convenience of a mechanochemical procedure.     

Green chemical synthesis for well-defined and sharply distributed SiO2@FexOy particles

Journal of Sol-Gel Science and Technology - Using a non-toxic precursor, we created a green chemical synthesis for colloidal spheres with a core@shell structure having a silica core and an iron...     

A versatile route for the synthesis of 3-(1′, 1′-dimethyllallyl)coumarins

Synthesis of 3-(′, 1′-dimethylallyl)herniarin and 3-(′, 1′-dimethylallyl)desmothosyherniarin has been carried out by a versatile route.     

Pure green chemical approach for synthesis of Ag2O nanoparticles

In this study, a green chemistry method is reported for the synthesis of Ag₂O nanoparticles with the utilization of starch molecules as a stabilizing agent. In particular, by simply adjusting the concentration of starch in the reaction media, the structure of A₂O nanoparticles can be engineered in disc and faceted shapes, which has been analyzed by transmission electron microscopy, UV-Vis spectroscopy, and X-ray diffraction technique. In addition, antibacterial activity of the prepared Ag₂O nanoparticles had been evaluated against food poisoning and pathogenic bacteria.     

A green chemical approach to the synthesis of tellurium nanowires

Starch, an economical and safe carbohydrate, has been found to be not only an effective reducing agent but also a new morphology-directing agent for the synthesis of tellurium nanowires using commercial H2TeO4 precursor. The obtained tellurium nanowires are of single-crystal in nature, with an average diameter of approximately 25 nm and length up to 10 microm. A possible synthetic mechanism involves the chain-shaped bioorganic molecule acting as a template for the one-dimensional growth of inorganic tellurium. The effects of different chain-shaped structures and concentrations of biomolecules on the nanowire morphology have been investigated and different one-dimensional structures, including thick rods, short nanowires, bunched nanowires, and assembled spikelet structures, have been fabricated. These experimental results have been found to be useful in substantiating the proposed synthetic mechanism.     

Microfluidic approach for rapid multicomponent interfacial tensiometry

We report a microfluidic instrument to rapidly measure the interfacial tension of multi-component immiscible liquids. The measurement principle rests upon the deformation and retraction dynamics of drops under extensional flow and was implemented for the first time in microfluidics (S. D. Hudson et al., Appl. Phys. Lett., 2005, 87, 081905 (ref. )). Here we describe in detail the instrument design and physics and extend this principle to investigate multicomponent mixtures, specifically two-component drops of adjustable composition. This approach provides fast real-time sigma measurements (on the order of 1 s), the possibility of rapidly adjusting drop composition and utilizes small sample volumes (approximately 10 microL). The tensiometer operation is illustrated with water drops and binary drops (water/ethylene glycol mixtures) in silicone oils. The technique should be particularly valuable for high-throughput characterization of complex fluids.