A piperidinium triflate catalyzed Biginelli reaction

A piperidinium triflate, 1,1,3,5-tetramethyl-4-oxo-2,6-diphenylpiperidinium triflate, in acetonitrile efficiently catalyzes one synthetic operational construction of biopertinent hydropyrimidines from respective aldehyde, β-dicarbonyl, and urea/thiourea building blocks.     

Synthesis of new furocoumarin analogues via cross-coupling reaction of triflate

Furocoumarins such as psoralen or angelicin showed important biological activities. We present here the synthesis of new furocoumarin analogues via Suzuki or Sonogashira cross-coupling reaction of triflate.     

Synthesis of 9Z-9-substituted retinoic acids by palladium catalyzed coupling reaction of a vinyl triflate with alkenyl stannanes

Palladium catalyzed cross coupling reactions of a vinyl triflate intermediate and various alkenyl stannanes afforded trisubstituted Z-olefins stereoselectively in high yields. These olefins were then converted to the corresponding 9Z-retinoic acids via Horner-Emmons reaction and subsequent basic hydrolysis in excellent yields.     

Silver triflate catalyzed reaction of 2-alkynylbenzaldoxime with aryne

A novel and unexpected reaction of 2-alkynylbenzaldoxime with aryne in the presence of silver triflate (10 mol %) under mild conditions is discovered. This reaction proceeds through 6-endo-cyclization, [3 + 2] cycloaddition, and rearrangement, leading to 2-oxa-6-aza-bicyclo[3.2.2]nona-6,8-diene derivatives in moderate to good yields.     

Attachment of the anthramycin acrylamide side chain by the palladium catalyzed coupling reaction of a vinyl triflate

Conversion of the 2-keto group in the pyrrolo ring of pyrrolo(1,4)benzodiazepines to the vinyl triflate takes place regiospecifically to yield the enamine. The triflate undergoes palladium catalyzed coupling reactions to attach the acrylamide side chain.     

Synthesis of a lignan skeleton via nickel- and palladium-phosphine complex catalyzed grignard coupling reaction of halothiophenes

A lignan skeleton is prepared in good yield through desulfurization of 3,4-dibenzyl-thiophene or 2,5-diaryl-3,4-dimethylthiophenes which are obtained by the nickel- or palladium-phosphine complex catalyzed Grignard cross-coupling reaction of halothiophenes.     

Synthesis of the cytotrienin A core via metal catalyzed C-C coupling

A synthetic approach to the C17-benzene ansamycins via metal catalyzed C-C coupling is described. Key bond formations include direct iridium catalyzed carbonyl crotylation from the alcohol oxidation level followed by chelation-controlled Sakurai-Seyferth dienylation to form the stereotriad, which is attached to the arene via Suzuki cross-coupling. The diene-containing carboxylic acid is prepared using rhodium catalyzed acetylene-aldehyde reductive C-C coupling mediated by gaseous hydrogen. Finally, ring-closing metathesis delivers the cytotrienin core.     

Synthesis of 1-aryl indoles via coupling reaction of indoles and aryl halides catalyzed by CuI/metformin

Ullmann-type C–N coupling reaction has been developed for the synthesis of 1-aryl indole derivatives by indoles and aryl halides in the presence of CuI/metformin (CuI/Met) in DMF. This method is very easy, rapid, and high yielding reaction for the synthesis of 1-aryl indoles. In particular, the metformin, which is used as ligand, is inexpensive and nontoxic that is considered to be relatively environmentally benign.     

Synthesis of pyrimidine derivatives via multicomponent reaction catalyzed by ferric chloride

An eco-friendly and practical approach was developed for the synthesis of pyrimidine derivatives via a one-pot, three-component coupling reaction of commercially available aldehydes, alkynes, and indazole3/triazole catalyzed by ferric chloride with good to excellent yields. The advantages of this method include environmentally friendly catalyst, easily available materials, and ease of product isolation.     

An unexpected silver triflate catalyzed reaction of 2-alkynylbenzaldehyde with 2-isocyanoacetate

An unexpected silver triflate catalyzed reaction of 2-alkynylbenzaldehyde with 2-isocyanoacetate provides an efficient route for the generation of isoquinolines. The reaction proceeds smoothly in air under mild conditions with high efficiency.     

Synthesis of Mannich type products via a three-component coupling reaction

The reactions of alkyl nitriles, acetyl chloride, aldehydes and β-ketoesters or simple ketones was studied for the one-pot synthesis of β-acetamido carbonyl compounds. It was observed that the reaction proceeds in the absence of Lewis acids. However, a Lewis acid catalyzes the reaction and several were tested. It was found that whereas Cu(OTf)₂ is suitable for the coupling of β-ketoesters with aldehydes, Sc(OTf)₃ is the best for ketones. A possible mechanism is proposed based on the isolation and characterization of an intermediate.     

Synthesis of indolequinones via a Sonogashira coupling/cyclization cascade reaction

A mild strategy for constructing indolequinone motifs is described on the basis of the Sonogashira reaction and a copper-catalyzed intramolecular cyclization cascade reaction. The first step involves the palladium- and copper-catalyzed reaction between halogenated naphthoquinone and terminal acetylene to generate a coupling product, which then reacts in a copper-catalyzed intramolecular cyclization with the nitrogen functional group adjacent to the carbon-carbon triple bond.     

Synthesis of gem-difluoromethylenated biflavonoid via the Suzuki coupling reaction

gem-Difluoromethylenated biflavonoid 1 was synthesized via the Suzuki coupling reaction. The key intermediate 6-iodonated flavone 4 was regioselectively synthesized by the use of AgOAc/I₂ under mild conditions without handling of a strongly toxic reagent. The key step was the formation of a flavone 3′-boronate 3 using a palladium-catalyzed exchange of the corresponding 3′-iodonated flavone with a diboron reagent.     

Stereoselective synthesis of amides possessing a vinylsilicon functionality via a ruthenium catalyzed silylative coupling reaction

An effective stereoselective synthesis of E-N-2-(silyl)vinylamides via silylative coupling of vinyl amides such as N-vinylpyrrolidinone, N-vinylphthalimide, and N-vinylformamide with vinyltrisubstituted silanes catalyzed by [RuH(Cl)(CO)(PCy₃)₂] I is described.     

Synthesis of 5-substituted 1H-tetrazoles catalyzed by ytterbium triflate hydrate

Various 5-substituted 1H-tetrazoles were synthesized from aryl nitriles, alkyl nitriles, and vinyl nitriles reacting with sodium azide. The tetrazoles were recovered in high yield under mild conditions when the reaction was catalyzed by ytterbium triflate hydrate in dimethylformamide. Other rare-earth and post-transition metal catalysts were also investigated.     

Synthesis of allyl cyanamides and N-cyanoindoles via the palladium-catalyzed three-component coupling reaction

The palladium-catalyzed three-component coupling reaction (TCCR) of aryl isocyanides, allyl methyl carbonate, and trimethylsilyl azide was conducted in the presence of Pd(2)(dba)(3).CHCl(3) (2.5 mol %) and dppe (1,2-bis(diphenylphosphino)ethane) (10 mol %). Allyl aryl cyanamides with a wide variety of functional groups were obtained in excellent yields. This palladium-catalyzed TCCR was further utilized for the synthesis of N-cyanoindoles. The reaction of 2-alkynylisocyanobenzenes, allyl methyl carbonate, and trimethylsilyl azide in the presence of Pd(2)(dba)(3).CHCl(3) (2.5 mol %) and tri(2-furyl)phosphine (10 mol %) at higher temperatures afforded N-cyanoindoles in good to allowable yields. (eta(3)-Allyl)(eta(3)-cyanamido)palladium complex, an analogue of the bis-pi-allylpalladium complex, is a key intermediate in the TCCR, and a pi-allylpalladium mimic of the Curtius rearrangement is involved to generate the (eta(3)-allyl)(eta(3)-cyanamido)palladium intermediate.     

Synthesis of C-nucleosides via coupling of ribosyl fluoride with typical aromatic heterocycles bearing a TMS group

The direct coupling reaction of D -ribosyl fluoride with typical π-excessive aromatic heterocycles such as furan, thiophene, pyrrole, benzofuran, benzothiophene, and indole and their trimethylsilyl derivatives was performed in the presence of boron trifluoride to afford the corresponding C-nucleosides in moderate to good yields.