Microwave-assisted decarboxylative three-component coupling of a 2-oxoacetic acid, an amine, and an alkyne

A novel and efficient microwave-assisted decarboxylative three-component coupling of a 2-oxoacetic acid, an amine, and an alkyne (OA(2)-coulpling) has been developed. This new multicomponent coupling constitutes an efficient approach for the synthesis of polysubstituted propargylamines in the presence of a catalytic amount of copper(I) catalyst.     

Synthesis of flavanones, azaflavanones, and thioflavanones catalyzed by PMA-SiO2 as a mild, efficient, and reusable catalyst

Abstract  

Cyclization of a variety of chalcones to flavanones catalyzed by 1 mol% phosphomolybdic acid (PMA) supported on silica as a mild, efficient, and reusable catalyst was carried out in high yields. PMA-SiO₂ is an efficient, inexpensive, and green catalyst which gave high conversion yields and could be recycled up to three times without significant loss in activity.     

Total syntheses of the marine illudalanes alcyopterosin I, L, M, N, and C

The combination of a modular assembly of enantiopure triynes and a powerful rhodium-catalyzed [2 + 2 + 2] alkyne cyclotrimerization reaction opens new and efficient entries to a set of alcyopterosins, including the first total synthesis of the alcyopterosins L, M, and C.     

One-pot synthesis of 1-monosubstituted-1, 2, 3-triazoles from 2-methyl-3-butyn-2-ol

An efficient method for the synthesis of 1-monosubstituted-1, 2, 3-triazoles from 2-methyl-3-butyn-2-ol under copper catalyst conditions has been developed through a one-step one-pot sequence. This method provides a concise and efficient pathway to synthesize 1-monosubstituted-1, 2, 3-triazole derivatives in good to excellent yields.     

Microwave-assisted green synthesis of anilines,phenols, and benzenediamines without transition metals,ligands, or organic solvents

A novel, microwave-assisted method producing anilines and phenols from activated aryl halides is reported. This high-yielding method reduces current reaction requirements and removes organic solvents and catalysts making a more efficient and eco-friendly alternative for the synthesis of important pharmaceutical building blocks.     

Synthesis, characterization, and preliminary intramolecular energy transfer studies of rigid, emissive, rhenium-linked porphyrin dimers

The reaction of pyridyl functionalized porphyrins with Re(CO)(5)Cl in THF results in the formation of porphyrin dimers which, despite incorporation of rhenium into the assemblies, remain fluorescent. The rigid compounds provide an efficient geometry and/or orbital pathway for singlet energy transfer, rendering these compounds suitable, in principle, for the study of both through-bond and through-space energy transfer. Derivatives containing both metallated and freebase porphyrins connected via the metal corners display efficient porphyrin-porphyrin energy transfer. The photophysical properties of the assemblies have been studied by both steady-state and time-resolved fluorescence techniques, yielding approximate rates and efficiencies for porphyrin-porphyrin energy transfer.     

Synthesis,Molecular Docking,Analgesic, and Anti-Inflammatory Activities of New 1,2,4-Oxadiazolo-Sulfonamides

Russian Journal of General Chemistry - In the present study novel 1,2,4-oxadiazolo sulfonamides 3a–3o are synthesized by an efficient method based on the reaction of 1,2,4-oxadiazole amines...     

Generalized Prediction of Enthalpies of Formation Using DLPNO-CCSD(T) Ab Initio Calculations for Molecules Containing the Elements H,C, N,O, F,S, Cl,Br

The prediction of thermochemical properties such as enthalpies of formation is of crucial importance, both in research and industrial applications, especially for systems involving not well-characterized molecules, such as biomass systems (bio-oils), or systems involving new compounds (new-generation refrigerants). It is highly desirable to obtain an efficient method by which these values can be predicted. Ab initio-based calculations can be very accurate for predicting gas phase thermochemical properties and are usually more versatile than group contribution methods. In this work, we propose a general extension of the work of Paulechka and Kazakov, using very accurate and efficient domain-based local pair natural orbital-coupled cluster theory ab initio calculations, to determine the enthalpies of formation of a broad variety of molecules. New sets of regressed atomic contributions are proposed for a larger group of elements: H, C, N, O, F, S, Cl, and Br. Excellent predictions are obtained for the most studied compounds (bio-oil compounds and refrigerants). © 2019 Wiley Periodicals, Inc.     

Fast, efficient, mild, and metal-free synthesis of pyrroles by domino reactions in water

(E)-β-Bromonitrostyrenes react with enaminones in water to afford pyrroles in excellent yields. The domino reaction constitutes a new, mild, and environmentally benign process for the fast and efficient synthesis of diverse pyrroles.     

Oxidation of Alkynyl Boronates to Carboxylic Acids,Esters, and Amides

A general efficient protocol was developed for the synthesis of carboxylic acids, esters, and amides through oxidation of alkynyl boronates, generated directly from terminal alkynes. This protocol represents the first example of C(sp)?B bond oxidation. This approach displays a broad substrate scope, including aryl and alkyl alkynes, and exhibits excellent functional group tolerance. Water, primary and secondary alcohols, and amines are suitable nucleophiles for this transformation. Notably, amino acids and peptides can be used as nucleophiles, providing an efficient method for the synthesis and modification of peptides. The practicability of this methodology was further highlighted by the preparation of pharmaceutical molecules.     

Oxidation of Alkynyl Boronates to Carboxylic Acids,Esters, and Amides

A general efficient protocol was developed for the synthesis of carboxylic acids, esters, and amides through oxidation of alkynyl boronates, generated directly from terminal alkynes. This protocol represents the first example of C(sp)−B bond oxidation. This approach displays a broad substrate scope, including aryl and alkyl alkynes, and exhibits excellent functional group tolerance. Water, primary and secondary alcohols, and amines are suitable nucleophiles for this transformation. Notably, amino acids and peptides can be used as nucleophiles, providing an efficient method for the synthesis and modification of peptides. The practicability of this methodology was further highlighted by the preparation of pharmaceutical molecules.     

Highly efficient aza-Baylis-Hillman reaction of N-tosylated imines with MVK, acrolein, and phenyl acrylate or alpha-naphthyl acrylate: Lewis base effects and a convenient method to synthesize alpha,beta-unsaturated beta-amino carbonyl compounds

This paper describes several highly efficient aza-Baylis-Hillman reactions of N-tosylated imines with MVK, acrolein, and phenyl acrylate or alpha-naphthyl acrylate in the presence of a Lewis base. In most cases, the reaction can be completed within 1 h using the appropriate Lewis base catalyst. An efficient method to synthesize beta-amino ketones, aldehydes and esters in high yields and short reaction time has been developed.     

Computer-assisted prediction of antioxidant activities and toxicities of ionol, 5-hydroxy-6-methyluracil, and their derivatives

A mathematical model for prediction of antioxidant activity (AOA) with a recognition level of ∼90% was developed using the SARD-21 computer system. Based on this model, structural modification of ionol and 5-hydroxy-6-methyluracil was carried out. A set including 32 potential antioxidants was generated. The interval levels of toxicity were theoretically predicted and the effect of structural fragments on the toxic properties of the most efficient potential antioxidants was analyzed. Structural attributes characteristic of highly efficient, low-toxicity antioxidants were revealed for the first time. Based on complex analyses of the AOA and toxicity, thirteen structures of potentially efficient low-toxicity antioxidants were proposed. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1274–1279, August, 2006.     

Micellar media for the efficient ring opening of epoxides with CN-, N3-, NO3-, NO2-, SCN-, Cl- and Br- catalyzed with Ce(OTf)4

Micellar media are introduced for the efficient ring opening of epoxides with sodium salts of nucleophiles such as CN-, N3-, NO3-, NO2-, SCN-, Br- and Cl-, catalyzed with Ce(OTf)4. This method is an efficient procedure for the synthesis of different beta-substituted alcohols under mild reaction conditions. The reaction with SCN- is an easy procedure for the high yielding preparation of epoxy sulfides.     

Gold-catalyzed 1,2-migration of silicon, tin, and germanium en route to C-2 substituted fused pyrrole-containing heterocycles

An efficient method for the synthesis of fused pyrroloheterocycles from diverse propargyl-substituted heterocycles in the presence of Au-catalyst has been developed. The cascade transformation proceeds via alkyne-vinylidene isomerization with concomitant 1,2-shift of hydrogen, silyl, and stannyl groups. Remarkably, it was also shown that previously unknown 1,2-migration of a germyl group upon alkyne-vinylidene rearrangement occurs under these reaction conditions. This method allows for mild and efficient synthesis of diverse C-2 substituted N-containing heterocycles.     

Bright,Multi-responsive,Sky-Blue Platinum(II) Phosphors Based on a Tetradentate Chelating Framework

A new class of highly efficient and stable, blue-phosphorescent Pt^II complexes based on a tetradentate chelating framework has been found to exhibit highly sensitive and reversible responses to multiple external stimuli including temperature, pressure, and UV irradiation with distinct phosphorescent color switching—from blue to red or white. Intermolecular excimer formation is the main origin of this intriguing multi-response phenomenon. Highly efficient singlet-oxygen sensitization by the Pt^II compounds yields UV-light-induced phosphorescence enhancement and color switching.     

Highly efficient, wavelength-tunable, gold nanoparticle based optothermal nanoconvertors

A photon-to-thermal energy conversion nanosystem based the near-infrared irradiation of one-dimensional gold nanoparticles (nanorods) is highly efficient and tunable to the incident wavelength. Using ambient photothermal detection, we observed a temperature rise of ca. 30 degrees C upon irradiating an aliquot of an aqueous nanoparticle suspension with a laser for 5 s. The temperature can be elevated even higher by embedding the particles into a poorly thermally conducting solid medium. The illuminated area of a sample containing nanorod particles embedded in a polyurethane matrix can be heated to >100 degrees C upon irradiation for 1 min. This optothermal conversion efficiency can be turned on selectively by tuning the wavelength to match that of the surface plasmon resonance of the particles. This specificity, with respect to the wavelength of the incident light, makes these highly efficient, particle-based, optothermal nanoconvertors suitable for potential use in multicolor detection on biochips and related sensors and as ideal contrasting agents for optoacoustic biomedical imaging applications.     

Syntheses of chloroisosulochrin and isosulochrin and biomimetic elaboration to maldoxin, maldoxone, dihydromaldoxin, and dechlorodihydromaldoxin

An efficient synthesis of chloroisosulochrin was accomplished using a novel ortho-selective chlorination of a phenol with sulfuryl chloride and 2,2,6,6-tetramethylpiperidine as the key step. Further elaboration by a biomimetic route converted chloroisosulochrin to dihydromaldoxin, maldoxone (lactone formed by dehydration of dihydromaldoxin), and maldoxin and isosulochrin to dechlorodihydromaldoxin and dechloromaldoxin.     

Synthetic Studies of Didemnaketals Analogue-Construction of the Intermediate (3S,5S,6R)-3,7-Dimethyl-5,6,7-trihydroxy-octanal

TheDidemnaketalsAandBhavebeenreportedtobesignificantinhibitorstoHlV-protease'.Inconnectionwiththetotalsynthesisofthiskindofcompounds,ourrecentresearchinterestisfocusedontheirsyntheticstudiesaswellassynthesisofananaloguel,whichincorPoratedthekeyspiroketalmoietyofthedidemnaketalsAandB.Basedontheretrosyntheticconsideration(Schemcl),thelinearintermediate2wouIdbeconstructedfrom3and4.Furthermore,4wouldbesynthesizedfrom( )-PuIegone5.Wehereinreportedastereoselectivesyntheticprocedureforthe(3S,5S…     

Efficient Synthesis of Functionalized Thiazoles from Acid Chlorides,Tetramethylthiourea, Ethyl Bromopyruvate,and Ammonium Thiocyanate

An efficient synthesis of ethyl 2‐(dimethylamino)‐1,3‐thiazole‐4‐carboxylates is described via a four‐component reaction between acid chlorides, tetramethylthiourea, ethyl bromopyruvate, and ammonium thiocyanate.