Ytterbium triflate-promoted tandem one-pot oxidation-Cannizzaro reaction of aryl methyl ketones

[reaction: see text] Ytterbium triflate was shown to be an effective catalyst in promoting the synthesis of either isopropyl esters or free alpha-hydroxy-arylacetic acids from substituted aromatic glyoxals and aryl methyl ketones, respectively. The reaction to provide acids starting from differently substituted ketones was carried out by an environmentally friendly method using an aqueous medium as a solvent and giving the adducts in 78-99% yield without any further purification after the usual workup.     

Iodine-catalyzed tandem oxidative coupling reaction: A one-pot strategy for the synthesis of new coumarin-fused pyrroles

The simple and facile strategy for the synthesis of 2,3-disubstituted-chromeno[4,3-b]pyrrole-4(1H)-ones has been established. This method describes the Kornblum oxidation reaction of acetophenones, followed by the Knoevenagle treatment of the resulted (het)arylglyoxals with active methylene compounds and consequently iodine-activated Michael type reaction with 4-amino coumarin in a one-pot manner to afford disubstituted chromeno[4,3-b]pyrrole-4(1H)-one derivatives.     

A tandem Heck-aza-Michael addition protocol for the one-pot synthesis of isoindolines from unprotected amines

A palladacycle-catalyzed tandem Heck-intramolecular aza-Michael reaction protocol has been developed for the one-pot synthesis of 1-substituted isoindolines from N-unprotected 2-bromobenzylamines and acrylates with high yields.     

A one-pot asymmetric organocatalytic tandem reaction for the synthesis of oxazine derivatives

An easy one-pot tandem reaction catalyzed by a chiral secondary amine for the synthesis of optically active oxazine derivatives has been performed and the corresponding substituted benzo[d]pyrido[2,1-b][1,3]oxazine derivatives were afforded in generally high yields (up to 99%) and excellent enantioselectivities (up to >99%).     

Copper-catalyzed oxidative synthesis of 2-oxo-acetamidines from one-pot three-component reaction of aryl methyl ketones,secondary amines and anilines

Some novel 2-oxo-acetamidines were synthesized via one-pot three-component reaction of acetophenones, secondary amines and anilines in presence of CuI as catalyst. The reaction involved in a oxidation process of C (sp³)H bonds of acetophenones in presence of air followed by aminations, and products were obtained in good to excellent yields (70–82%) in simple work-up procedure.     

A facile one-pot synthesis of alkyl aryl sulfides from aryl bromides

A convenient one-pot synthetic method for the formation of alkyl aryl sulfides from various alkyl halides and lithium aryl thiolates that are prepared in situ by direct halogen-lithium exchange is reported. In particular, the method overcomes many of the problems encountered in previous reports; it is very quick, catalyst-free, and does not involve use of unstable aryl thiols.     

Palladium-catalyzed sequential one-pot reaction of aryl bromides with O-homoallylhydroxylamines: synthesis of N-aryl-beta-amino alcohols

The palladium-catalyzed sequential one-pot N-arylation-carbo-amination-C-arylation of O-homoallylhydroxylamines with two different aryl bromides provides rapid entry to differentially arylated N-aryl-3-arylmethylisoxazolidines in good yields with excellent diastereoselectivity. The obtained isoxazolidines can be reductively cleaved to cis-N-aryl-beta-amino alcohols in short times and in high yields at room temperature.     

A one-pot synthesis of tertiary amines from amines,lactams and urethanes

A one-pot synthesis of unsymmetrical tertiary amines from amides, lactams and urethanes has been developed. The reaction is general for all cases examined with the exception of N-aryl containing examples, which are not accessible by this method.     

Novel tandem reaction of benzyne with cyclic ethers and active methines: synthesis of ω-trichloroalkyl phenyl ethers

The reaction of benzenediazonium carboxylate with chloroform in refluxing tetrahydrofuran afforded 5,5,5-trichloropentyl phenyl ether in 61% yield along with benzoic acid (7%). When dichloroacetonitrile was used as a reactant, 5,5-dichloro-5-cyanopentyl phenyl ether was obtained in 65% yield. Reactive benzyne derived from diazonium carboxylate initially reacted with THF to give a dipole intermediate, which further reacted with chloroform or dichloroacetonitrile to give ring opened products.     

A one-pot tandem synthesis of various 1,2-disubstituted benzimidazoles

A facile method to synthesize various 1,2-disubstituted benzimidazoles is developed. It is suggested that formation of a Meisenheimer adduct between the substrate, amine, and solvent aids the N-arylation process. The generality of the protocol is demonstrated by the efficient reactions involving numerous substituents ranging from electron-withdrawing groups to electron-donating groups.     

Base-mediated reaction of vinyl bromides with aryl azides: one-pot synthesis of 1,5-disubstituted 1,2,3-triazoles

A one-pot base-mediated reaction of azides and β- or α-vinyl bromides has been reported. The effects of bases and solvents have been investigated in the process. A variety of 1,5-disubstituted triazoles were prepared in low to good yields. Further studies reveal that the corresponding alkynes were produced as intermediates via elimination reaction. Under the same reaction conditions, the reactions of alkyl alkynes with phenyl azide would give 1,5-disubstituted 1,2,3-triazoles.     

A practical one-pot process for α-amino aryl ketone synthesis

An efficient, convenient, high-yielding synthesis of α-amino aryl ketones is described, involving the one-pot deprotonation-transmetallation-arylation of a Weinreb amide while retaining chirality of the original amide.     

Facile one-pot synthesis of a photo patternable anthracene polymer

A polycyclic aromatic compound, anthracene, was covalently connected through a methylene bridge via Friedel-Crafts alkylation reaction. Thus, a highly fluorescent anthracene polymer (PMAn) linked by a methylene unit was prepared in one step to produce a conjugated-nonconjugated spacer-type polymer through its reaction with chloromethyl methyl ether (CME) and FeCl₃ at 0 °C. The resultant polymer was soluble in organic solvents and showed significantly higher fluorescence (quantum yield = 0.80) compared to monomeric anthracene, 9-methylanthracene, in chloroform solution. Fluorescent thin films of PMAn as solid media were prepared with high film uniformity. The emission of the film was extinguished when the film was exposed to a UV source, due to the photodimerization of anthracene unit. A fluorescent gap electrode pattern was formed on the polymer film-forming average step depth of 8 nm and 14 nm, after 30 and 60 min irradiation with a UV light, respectively. The photo patternable fluorescent polymer afforded a convenient method of image formation and patterning.     

A tandem one-pot aqueous phase synthesis of thiazoles/selenazoles

The first ever tandem one-pot synthetic protocol for the synthesis of thiazoles/selenazoles from alkynes via the formation of 2,2-dibromo-1-phenylethanone is reported. The reaction is catalyzed by β-cyclodextrin in aqueous medium and resulted in good yields.     

A new Vilsmeier-type reaction for one-pot synthesis of pH sensitive fluorescent cyanine dyes

A new Vilsmeier-type reaction is suggested for the synthesis of novel indocarbocyanine pH sensors, which are fluorescent when protonated but nonfluorescent upon proton abstraction. These sensors show significant ratiometric UV-visible as well as fluorescence spectral changes upon subtle variation of pHs with pK_a values near neutral.     

SnCl4-catalyzed reaction of o-benzoquinones and aryl acetylenes: an unprecedented one-pot synthesis of tropone derivatives

Highly substituted tropone derivatives were obtained as a result of SnCl4-catalyzed cycloaddition of 3-methoxy-substituted o-benzoquinones with aryl acetylenes and subsequent rearrangement of the adducts with concomitant decarbonylation.     

A new one-pot three-component condensation reaction for the synthesis of 2,3,4,6-tetrasubstituted pyridines

The one-pot three-component condensation of a beta-ketoester, ammonia and an alkynone in the presence of a Br?nsted or Lewis acid or Amberlyst 15 ion exchange resin provided 2,3,6-trisubstituted or 2,3,4,6-tetrasubstituted pyridines directly in good yield and with total regiocontrol.     

Quinoxaline synthesis in novel tandem one-pot protocol

A variety of quinoxalines were synthesized via tandem one-pot procedure for the first time in water medium. The key strategy was the in situ preparation of α-halo-β-keto esters by the reaction of N-bromo succinimide with β-keto esters and further condensation with phenylene diamines. This novel eco-friendly approach offers an easy, efficient, and mild synthesis of highly substituted quinoxalines in good yields.     

N-Dealkylation of aliphatic amines and selective synthesis of monoalkylated aryl amines

Highly selective alkyl transfer processes of mono-, di- and trialkyl amines in the presence of the Shvo catalyst have been realized; in addition, a general method for N-alkylation of aniline with di- and trialkyl amines is presented.