One-pot multicomponent synthesis of polysubstituted indolizines

Concise and efficient four-component tandem approaches to polysubstituted indolizines have been developed under metal-free and mild aerobic conditions in refluxing acetonitrile. The mechanism of the novel reactions was proposed involving the formation of pyridinium ylides and α,β-unsaturated ketones with subsequent 1,3-dipolar cycloaddition and aromatization reaction.     

Efficient synthesis of functionalized 6-substituted-thiosalicylates via microwave-promoted Suzuki cross-coupling reaction

Functionalized 6-substituted-thiosalicylates are key intermediates for the synthesis of pyrimidinyl(thio)salicylic acids, a group of important herbicides targeting plant acetohydroxyacid synthase. Therefore, it is of great interest to develop an efficient method for the syntheses of 6-substituted-thiosalicylates. Herein, we have developed a direct and efficient method for the synthesis of functionalized 6-substituted-thiosalicylates (4) from aryl iodide (1) by using an improved microwave-assisted Suzuki cross-coupling reaction. Almost all the reactions proceeded smoothly and afforded moderate to excellent yields of products. Moreover, this protocol is obviously superior to the traditional available methods and could be utilized to synthesize pyrimidinyl(thio)salicylic acid and its derivatives.     

Efficient synthesis of functionalized 6-arylsalicylates via microwave-promoted Suzuki cross-coupling reaction

Functionalized 6-arylsalicylate substructures occur in a variety of pharmacologically relevant natural products and bioactive compounds. They are also broadly used as important intermediates in organic synthesis. Traditional synthetic methods have suffered from some drawbacks, such as relatively harsh reaction conditions, narrow range of substrates, and poor yields. Utilizing microwave irradiation, the synthesis of functionalized 6-arylsalicylates via a Suzuki cross-coupling has been developed with a wide range of substrates. Almost all the reactions proceeded smoothly and afforded moderate to excellent yields of products, which indicated that electronic effects and steric modifications have little effect on this reaction.     

Parallel, solution phase synthesis of dihydropyridine miticides via a versatile multicomponent reaction

A novel class of highly active dihydropyridine miticides was prepared using a multicomponent reaction process. The initial lead was rapidly optimized using solution phase parallel synthesis techniques and a positional scanning approach. Detailed structure-activity relationships were developed for the amino and carbonyl components of the molecule and used to select the best candidates for broad field testing. The chemistry, biology and toxicology of these compounds will be presented along with numerous structural variants of the reaction products.     

Efficient synthesis of 4-substituted pyrazole via microwave-promoted Suzuki cross-coupling reaction

Pyrazoles and their derivatives are important heterocycles found in nature and present in numerous bioactive compounds.In contrast to 3 or 5-aryl pyrazole,the preparation of 4-aryl pyrazole is fairly rare.Utilizing microwave irradiation,the synthesis of 4-substituted-arylpyrazole via Suzuki cross-coupling has been developed with a wide range of substrates.The remarkable advantages of this method are mild reaction conditions,simple operation,high yield,and short reaction time.Product structures were identified by MS 1H NMR 13C NMR,and elemental analysis.     

Pd-catalyzed one-pot multicomponent coupling reaction for the highly regioselective synthesis of polysubstituted benzenes

[Reaction: see text] Tetrasubstituted benzenes can be efficiently synthesized in a regioselective manner from alkynes and 2-bromoacrylates by palladium-catalyzed cascade Sonogashira coupling-benzannulation reaction.     

An efficient and facile synthesis of highly substituted 2,6-dicyanoanilines

A one-pot procedure for the synthesis of substituted 2,6-dicyanoanilines starting from readily available ynones and malononitrile has been developed. For instance, penta-1,4-diyn-3-one is converted into the acetylene-substituted aniline derivative 1 in good yield. Upon photoexcitation, this chromophore shows a strong blue emission with a high quantum yield. The ground- and the excited-state geometries, charge distributions, and excitation energies of 1 have been evaluated by ab initio calculations.     

A straightforward one-pot multicomponent synthesis of polysubstituted pyrroles

Polysubstituted pyrroles were efficiently synthesized in moderate yields by a one-pot multicomponent reaction starting from primary amines, ethyl glyoxalate and 2-bromoacetophenones in the presence of pyridine in refluxing acetonitrile. This methodology was utilized to synthesize a highly substituted benz[g]indole.     

Solid-phase synthesis of modified oligopeptides via Passerini multicomponent reaction

A Passerini multicomponent reaction of N-protected-α-aminoaldehydes, carboxylic acids and solid-supported isocyanides has been successfully performed on Lantern™. The initially formed N-protected-β-amino-α-acyloxyamides gave, by piperidine-promoted deprotection and concomitant acyl migration, β-acylamino-α-hydroxyamides which, by OH-oxidation and cleavage off the solid support, provided β-acylamino-α-oxoamides. Formation and disappearance of the isocyano group has been followed using photoacoustic IR spectroscopy, a fast, reliable and non-disruptive technique that has been successfully applied for the first time to macroscopic solid supports.     

ZnO-nanoparticle-promoted synthesis of polyhydroquinoline derivatives via multicomponent Hantzsch reaction

Abstract  

Zinc oxide nanoparticles are used as an effective and reusable catalyst for one-pot, four-component couplings of aldehydes, dimedone, active methylene compounds, and ammonium acetate to produce polyhydroquinoline derivatives under solvent-free conditions at room temperature. Compared with other methods, satisfactory results are obtained with high yields, short reaction times, and simplicity in the experimental procedure. The catalyst could easily be recycled and reused four times without noticeable decrease in catalytic activity.     

An efficient one-pot synthesis of strongly fluorescent (hetero)arenes polysubstituted with amino and cyano groups

An efficient one-pot synthesis simultaneously results in three types of densely substituted mono-, di- and tetracyclic π-systems, which can easily be isolated. Each chromophore presents a strong fluorescence emission, either in the red, green or blue part of the spectrum.     

Divergent synthesis of functionalized thioethers via multicomponent reaction of benzynes

Diverse functionalized thioethers were efficiently synthesized through the multicomponent reaction of benzynes, cyclic thioethers and different nucleophiles. Both inorganic salts (KF, KCl, KBr, and KSCN) and silylated reagents (TMSCN, TMSN₃, TMSCl) can be utilized as efficient nucleophiles for the reaction.     

Novel and efficient synthesis of iminocoumarins via copper-catalyzed multicomponent reaction

A variety of substituted iminocoumarins are prepared in good to excellent yields via a copper-catalyzed multicomponenet reaction of sulfonyl azides, terminal alkynes, and salicylaldehydes or o-hydroxylacetophenones. The method is general, mild, versatile, and efficient. A plausible mechanism for the domino process is proposed.     

Regioselective synthesis of polysubstituted pyridines via hetero-Diels-Alder reaction of isotellurazoles with acetylenic dienophiles

Treatment of substituted isotellurazoles or their Te-oxides with acetylenic dienophiles efficiently afforded polysubstituted pyridine derivatives through a pathway involving hetero-Diels-Alder reaction of isotellurazoles and the subsequent tellurium extrusion from the intermediary cycloadducts.     

Three-component synthesis of polysubstituted benzene derivatives via Diels-Alder reaction of cyclopentadienone acetal with alkyne

An efficient and regioselective synthesis of polysubstituted benzene derivatives was achieved via multicomponent reaction of a substituted cyclopropenone acetal and two alkyne molecules. The synthesis utilizes cyclopentadienone acetal as an intermediate and enables regioselective [2+2+2] assembly of the three-components into a benzene ring. A variety of polysubstituted benzene derivatives of synthetic and structural interest have been synthesized.     

One-pot facile synthesis of polysubstituted pyridines via tandem reaction of the Blaise reaction intermediates and 3-formylchromones

A novel tandem one-pot method for the synthesis of polysubstituted pyridine derivatives has been developed via Knoevenagel-type reaction and subsequent 6π electrocyclization of the Blaise reaction intermediates and 3-formylchromones. Short reaction time, moderate to good yields and excellent functional group tolerance have been accomplished in this protocol.     

An efficient organocatalyzed multicomponent synthesis of diarylmethanes via Mannich type Friedel-Crafts reaction

We have developed an efficient organocatalyzed, multicomponent synthesis of diarylmethane derivatives from tertiary aromatic amines, formaldehyde and 2-naphthols via Mannich type Friedel-Crafts reaction. Several organocatalysts such as (−)-chinchonidine, l-proline, l-thiaproline, and l-pipecolonic acid have been screened for the reaction but the best results were obtained with l-proline. In this Mannich type Friedel-Crafts alkylation, tertiary aromatic amines react with formaldehyde-proline adduct to generate 1-(4-(dimethylamino)benzyl)pyrrolidinium-2-carboxylate intermediate, which undergoes nucleophilic addition to give substituted diarylmethanes in excellent yields.