Carbonylative Sonogashira coupling of terminal alkynes with aqueous ammonia

[reaction: see text] Carbonylative coupling of phenylethyne with 4-methoxy-1-iodobenzene in the presence of 1 mol % PdCl(2)(PPh(3))(2), 2 equiv of 0.5 M aqueous ammonia, and CO (1 atm) gives the corresponding alpha,beta-alkynyl ketone in 72% isolated yield after stirring at room temperature for 41 h, while noncarbonylative coupling product is not obtained.     

Copper-free Sonogashira coupling of cyclopropyl iodides with terminal alkynes

The substrate scope of the copper-free Sonogashira coupling has been successfully extended to cyclopropyl iodides, allowing an efficient access to a wide variety of functionalized alkynyl cyclopropanes.     

Sonogashira cross-coupling reaction of organotellurium dichlorides with terminal alkynes

The Sonogashira cross-coupling reaction of vinylic and heteroaromatic tellurium dichlorides has been explored, yielding the corresponding enynes and 2-alkynyl substituted heteroaromatic compounds. The reaction was carried out with PdCl₂/CuI as catalysts and triethylamine as base, using methanol as solvent. The reaction proceeded under mild conditions and the cross-coupled products were obtained in good yields and in a stereoconservative manner.     

Copper-catalyzed coupling of pyridines and quinolines with alkynes: a one-step, asymmetric route to functionalized heterocycles

A copper (I)-catalyzed, asymmetric method to directly functionalize pyridines, quinolines, and isoquinolines with terminal alkynes is described. The reaction is readily diversified to incorporate a range of pyridine-based heterocycles and electron-rich or electron-poor alkynes. This provides a straightforward alternative to nucleophilic or cross-coupling approaches to directly derivatize these heterocycles, and yields useful propargylcarbamates.     

Efficient copper-free PdCl2(PCy3)2-catalyzed Sonogashira coupling of aryl chlorides with terminal alkynes

Under copper-free conditions and with Cs2CO3 as a base, PdCl2(PCy3)2 showed high catalytic activity for cross-coupling of electron-rich, electron-neutral, and electron-deficient aryl chlorides with a variety of terminal alkynes in DMSO at 100-120 degrees C affording internal arylated alkynes in good to excellent yields.     

Facile synthesis of fluorinated α-imino alkynes by the coupling reaction of imidoyl iodides with terminal alkynes

A series of N-arylbromodifluoroacetimidoyl iodides and 1-alkynes were converted into α-imino alkynes by using Pd(Ph₃)₂Cl₂/CuI as the catalyst under mild conditions. The reaction proceeded smoothly to give the coupling products in good to excellent yields.     

Cross coupling of polybromoiodobenzenes with some terminal alkynes

Sonogashira reactions of pentabromoiodobenzene and tetrabromo-1,4-diiodobenzene with various terminal alkynes at 20°C in benzene resulted in selective replacement of the iodine atoms with formation of the corresponding alk-1-yn-1-yl-substituted polybromobenzenes.     

Facile Cu-free Sonogashira cross-coupling of nucleoside C-6 arylsulfonates with terminal alkynes

The combination of PdCl₂[CH₃CN]₂ with XPhos is an efficient catalytic system for the Sonogashira-type cross-coupling of 2′-deoxyguanosine O⁶-arylsulfonates with terminal alkynes. The reactions generally proceed under mild conditions requiring no Cu co-catalyst to give the corresponding C-6-alkynylated deoxynucleosides in moderate to good yields.     

Cyclopalladated ferrocenylimines: efficient catalysts for homocoupling and Sonogashira reaction of terminal alkynes

A novel pathway for homocoupling of terminal alkynes has been described using cyclopalladated ferrocenylimine 1 or 2/CuI as catalyst in the air. This catalytic system could tolerate several functional groups. The palladacycle 2 in the presence of n-Bu₄NBr as an additive could be applied to Sonogashira cross-coupling reaction of aryl iodides, aryl bromides, and some activated aryl chlorides with terminal alkynes under amine- and copper-free conditions, mostly to give moderate to excellent yields.     

Palladium-catalyzed oxidative alkynylation of heterocycles with terminal alkynes under air conditions

Pd-Catalyzed oxidative alkynylation of azoles with terminal alkynes was developed via simultaneous activation of both heterocyclic sp(2) C-H and alkynyl sp C-H bonds. The choice of palladium catalyst source and external base resulted in being important factors for performing the reaction with high efficiency and selectivity, and air was successfully utilized as an environmental oxidant in the present alkynylation procedure.     

Copper-, ligand- and solvent-free synthesis of ynones by coupling acid chlorides with terminal alkynes

A general and efficient copper-, ligand- and solvent-free synthesis of ynones by coupling of a wide range of acid chlorides with terminal alkynes catalyzed by palladium(II) acetate at room temperature is reported.     

FeCl3/PPh3-catalyzed Sonogashira coupling reaction of aryl iodides with terminal alkynes

Conditions for a FeCl₃/PPh₃-catalyzed and palladium-, copper-, amine free-Sonogashira coupling reaction of aryl halides with terminal alkynes are reported. The protocol was applicable to a wide variety of substituted aryl iodides and alkynes with different steric and electronic properties and gave excellent yields of the desired coupling products.     

The thermoregulated ligand–palladium‐catalyzed carbonylative Sonogashira coupling of aryl iodides with terminal alkynes in water

The carbonylative Sonogashira coupling of aryl iodides with terminal alkynes was studied by using thermoregulated ligand–palladium as an efficient and reusable catalyst at 80 °C in water. The corresponding alkynone products were obtained in good to excellent yields under 1 atm of carbon monoxide. The isolation of the products was readily achieved by extraction with ethyl acetate, and the catalyst recovered in water can be reused and recycled up to four times without significant loss in catalytic activity. Copyright © 2015 John Wiley & Sons, Ltd.     

Palladium-catalyzed diastereoselective coupling of propargylic oxiranes with terminal alkynes

[reaction: see text] A diastereoselective coupling of propargylic oxiranes with terminal alkynes has been developed with use of a palladium catalyst. The stereochemistries of the resulting 4-alkynyl-substituted 2,3-allenols have been altered depending on the palladium catalyst. An optically active anti-substituted allene was synthesized from the reaction of an enantiomerically enriched propargylic oxirane without loss of chirality.     

AIBN-initiated radical addition of gem-difluorinated alkyl iodides to alkynes and the Pd-catalyzed Sonogashira coupling reaction of E-phenyl difluoromethylene vinylic iodides with terminal alkynes

The addition of gem-difluorinated alkyl iodides to alkynes initiated by AIBN neatly gave the corresponding difluoromethylene vinyl iodides among which the stereoselectivity of aromatic acetylenes was high. The further coupling reaction of E-phenyl difluoromethylene vinyl iodides with terminal alkynes in the presence of catalytic palladium afforded the substituted difluorinated enynes.     

A rapid, four-component synthesis of functionalized thiazoles

An efficient synthesis of 2-(dialkylamino)-4-phenyl)-1,3-thiazol-5-yl)(phenyl)methanone using acid chlorides, secondary amines, 2-bromoacethophenone and ammonium thiocyanate is described.     

Practical synthesis of functionalized terminal alkynes, 3,3,3-triethoxypropyne and ketal protected prop-2-ynones

Practical and economical synthesis of synthetically valuable 3,3,3-triethoxypropyne, ketal protected phenyl and methyl substituents prop-2-ynones is described. Bromination and subsequent 18-crown-6 catalyzed elimination of triethylorthoacrylate and ketal protected terminal alkenes with methyl and phenyl substituent which are inturn readily available from triethylorthopropionate, 3-chlorobutan-2-one and propiophenone afforded multigram quantities (>10?g) of corresponding functionalized terminal alkynes. Exploration of the synthetic utility of these alkynes is also demonstrated by the acetylenic substitution of the phenylalaninol derived 1,2-cyclic sulfamidate to deliver chiral alkynylated amines.     

A novel and direct synthesis of 2-alkyl-5-aryl disubstituted oxazoles

A direct and efficient method for the preparation of 2-alkyl-5-aryl disubstituted oxazoles was realized by reaction of aromatic -methyl ketones with various aliphatic nitriles in the presence of Ti(OTf)₃.