A highly selective photoinduced selenoperfluoroalkylation of terminal acetylenes by using a novel binary system of perfluoroalkyl iodide and diphenyl diselenide

Upon irradiation through Pyrex with a xenon lamp (hν>300 nm), terminal acetylenes undergo highly selective selenoperfluoroalkylation with perfluoroalkyl iodide and diphenyl diselenide. In this reaction, perfluoroalkyl and phenylseleno groups are selectively introduced into the terminal and internal positions of acetylenes, respectively.     

Electron-Deficient Acetylenes as Three-Modal Adjuvants in SNH Reaction of Pyridinoids with Phosphorus Nucleophiles

Publications covering a new easy metal-free functionalization of pyridinoids (pyridines, quinolines, isoquinolines, acridine) under the action of the system of electron-deficient acetylenes (acetylenecarboxylic acid esters, acylacetylenes)/P-nucleophiles (phosphine chalcogenides, H-phosphonates) are reviewed. Special attention is focused on a S_N^H reaction of the regioselective cross-coupling of pyridines with secondary phosphine chalcogenides triggered by acylacetylenes to give 4-chalcogenophosphorylpyridines. In these processes, acetylenes act as three-modal adjuvants (i) activating the pyridine ring towards P-nucleophiles, (ii) deprotonating the P-H bond and (iii) facilitating the nucleophilic addition of the P-centered anion to a heterocyclic moiety followed by the release of the selectively reduced acetylenes (E-alkenes).     

Alkynylation of N-tosylimines with aryl acetylenes promoted by ZnBr2 and N,N-diisopropylethylamine in acetonitrile

We found a suitable condition for the effective alkynylation of N-tosylimines with aryl acetylenes. The reaction of N-tosylimines and aryl acetylenes in the presence of ZnBr₂ and DIEA (N,N-diisopropylethylamine) in CH₃CN afforded the desired N-tosyl propargylamines in moderate to good yields.     

Efficient synthesis of substituted thieno[3,2-e]indoles

Efficient cyclization reactions of 5-aminobenzothiophene derivatives with internal and terminal acetylenes, giving 7- and 8-substituted thieno[3,2-e]indoles, are described. The reaction of 4-iodo-5-(methylsulfonamido)benzothiophene with terminal alkynes gave 7-substituted thienoindoles using general Sonogashira reaction conditions. Reaction of 5-amino-4-iodobenzothiophene with internal acetylenes, using Larock's heterocyclization reaction conditions, gave 7,8-disubstituted thieno[3,2-e]indoles.     

Copper-mediated trifluoromethylation of potassium alkynyltrifluoroborates with Langlois' reagent

Synthesis of trifluoromethylated acetylenes by copper-mediated trifluoromethylation of potassium alkynyltrifluoroborates with CF₃ radicals generated from NaSO₂CF₃ and tert-butyl hydroperoxide (TBHP) is communicated. The trifluoromethylated acetylenes were obtained in good to moderate yields. The presented method tolerates a wide range of aromatic, heteroaromatic, and aliphatic potassium alkynyltrifluoroborates.     

Synthesis of new halo-containing acetylenes and their application to the synthesis of azoles

The convenient synthesis of ten halo- and an isoxazole-containing acetylenes from the reaction of acetylenes with n-butyl lithium and subsequent reaction with an electrophile agent (ethyl trichloroacetate, ethyl dichloroacetate, trifluoroacetic anhydride, 3-methylisoxazol-5-carbonyl chloride, carbon tetrachloride and 1,1,1-trifluoro-4-ethoxy-3-buten-2-one) in moderated to good yields is reported. The application of 1,1,1-trichloro-4-phenyl-3-butyn-2-one on the synthesis of two azoles is also showed.     

Chlorochalcogenation of acetylenes with benzenesulfen-(or selenen)amides and Tin(IV) chloride

Benzenesulfenamides and benzeneselenenamides reacted with terminal and internal acetylenes (hex-1-yne, phenylacetylene, hex-3-yne, but-2-yne-1,4-diol, and diphenylacetylene) in the presence of SnCl₄ to give the corresponding chloroethenyl sulfides and selenides. From symmetric acetylenes, only E isomers (E)-ArXCR=CClR (X = S, Ar = Ph, 4-ClC₆H₄; R = Et, Ph, HOCH₂; X = Se, Ar = Ph, R = Et) were formed. The reactions of benzenesulfenamide with terminal acetylenes, apart from the corresponding Markownikoff and anti-Markownikoff adducts (PhSCH=CClR and PhSCR=CHCl, R = Bu, Ph) gave ethynyl sulfides PhSC=CR (R = Ph, Bu) and cis/trans-isomeric 1,2-bis(phenylsulfanyl)chloroethenes PhSCR=CClSPh (R = Ph, Bu). The results were interpreted assuming intermediate generation of sulfenyl and selenenyl chlorides via reaction of sulfen-and selenenamides with SnCl₄.     

Palladium-copper catalysed heteroannulation of acetylenic compounds: an expeditious synthesis of isoindoline fused with triazoles

A convenient and general method for the synthesis of isoindoline fused with triazoles from ortho-iodobenzyl azide and acetylenes through palladium-copper catalysis is described.     

Click reaction on in situ generated β-azidostyrenes from cinnamic acid using CAN-NaN3: synthesis of N-styryl triazoles

N-Styryl triazoles are synthesized in one-pot starting with azido styrene obtained in situ from cinnamic acids and various acetylenes.     

A convenient and efficient ring-opening reaction of aziridines with acetylenes and synthesis of dihydropyrroles

In the presence of ^tBuOK, reaction of acetylenes with N-Ts substituted aziridines derived from both cyclic and acyclic alkenes at room temperature gave rise to homopropargylamines in good to high yields and in high regioselectivity. Not only Ph- and Me₃Si-substituted acetylenes but also acetylene itself was suitable reagents. Treatment of ring-opening products with I₂ and AgOAc in the presence of K₂CO₃ provided dihydropyrroles in high yields. One-pot synthesis of dihydropyrroles was also realized by the reaction of aziridines and phenylacetylene in the presence of NaH followed by the treatment with I₂ and AgOAc.     

Facile syntheses of various per- or polyfluoroalkylated internal acetylene derivatives

Treatment of per- or polyfluoroalkylated vinyl iodides 5 with 2 equiv. of n-BuLi in THF produced the corresponding lithium acetylides in situ, which were transformed into zinc acetylides by the addition of ZnCl₂·TMEDA complex into the reaction mixture. The in situ generated zinc acetylides were exposed to the cross-coupling conditions such as ArI/cat. Pd(PPh₃)₄, reflux, 6-12 h, giving rise to the desired per- or polyfluoroalkylated acetylenes in high yields. In the case of trifluoromethylated acetylene, commercially available 2-bromo-3,3,3-trifluoropropene 6 could also be used instead of 5 as the starting material. In the acetylenes having a fluoroalkyl group and an aliphatic side chain, vinyl iodides 7, prepared by radical addition of perfluoroalkyl iodide to terminal acetylenes, were treated with t-BuOK at room temperature or at the reflux temperature of benzene, affording the desired compounds in good yields.     

Solvolytic cleavage of alkenylpentafluorosilicates catalyzed by copper(II) acetate. A stereoselective synthesis of (E)-alkenyl ethers from alkynes

(E)-Alkenylpentafluorosilicates, obtainable from acetylenes via hydrosilylation-silicate formation, react with alcohols in the presence of a catalytic amount of copper(II) acetate under an atmosphere of air (oxygen) at room temperature to form (E)-alkenyl ethers stereoselectively in satisfactory yields. Similar reaction with water gives aldehydes.     

Synthesis of pyrrolo[2,1-a]isoquinolines from activated acetylenes, benzoylnitromethanes, and isoquinoline

Isoquinoline reacts smoothly with aroylnitromethanes in the presence of dialkyl acetylenedicarboxylates and dibenzoylacetylene to produce pyrrolo[2,1-a]isoquinolines in good yields. Quinoline and benzothiazole also react in a similar way. Pyridine and N-methylimidazole catalyze the reaction between nitromethane derivatives with electron-deficient acetylenes to produce highly functionalized isoxazoles.     

Synthesis of the end-capped 5-(N,N-dimethylamino)naphthyl-1-ethynyl derivatives and their 1,4-di[5-(N,N-dimethylamino)naphthyl]-1,3-butadiynes: anti rotamer structure

A new family of the end-capped 5-(N,N-dimethylamino)naphthylethynyl chains were synthesized, as terminal acetylenes or poly(yne) structures, by heterocoupling between 5-iodo-N,N-dimethylnaphthalen-1-amine and 2-methyl-3-butyn-2-ol or 4-(5-iodo-1-naphthyl)-2-methyl-3-butyn-2-ol, catalyzed by the palladium-copper system. Catalytic homocoupling of the terminal acetylenes, affords to 1,4-dinaphthyl-1,3-butadiyne nanostructures. X-ray diffraction analysis of 1,4-di(α-naphthyl)-1,3-butadiyne shows that the naphthalene rings are in the anti configuration along the acetylene axis. All the conjugated compounds show an important fluorescent emission radiation.     

Metal-free synthesis of quinolines by direct condensation of amides with alkynes: revelation of <Emphasis Type="Italic">N</Emphasis>-aryl nitrilium intermediates by 2D NMR techniques

Employing triflic anhydride/2-fluoropyridine as an activation system, the coupling reactions of secondary N-aryl amides with terminal alkynes yielded substituted quinolines in moderate to excellent yields. The reaction tolerated both electron-donating and electron-withdrawing groups at the benzamide moiety. Electron-rich aryl acetylenes served as excellent coupling partners, and aliphatic terminal alkynes such as cyclopropyl and conjugate vinyl acetylenes could also be used as reaction partners. By means of 2D NMR techniques (heteronuclear multiple bond correlation (HMBC), heteronuclear single quantum correlation (HSQC)), nitrilium ions were probed as reactive intermediates which are in contrast with that suggested by Movassaghi on the basis of in situ IR monitoring experiments. On the basis of these results, a plausible mechanism for the formation of quinolines was suggested.     

Simple preparation of iron stabilized carboxonium ions. Concurrent complexation,rearrangement and alcohol addition to terminal acetylenes

CpFe(CO)₂[C(OEt)R]BF₄ complexes can be prepared by reaction of CpFe(CO)₂(isobutylene)BF₄ with monoalkylated acetylenes in methylene chloride/ethanol solutions. Methyl propiolate yields methyl trans-2-ethoxy-acrylate, in a reaction catalytic in CpFe(CO)₂(isobutylene)BF₄, and internal acetylenes can be transformed to CpFe(CO)₂(vinyl ether)BF₄ complexes.     

Orbital symmetry analysis of the reaction of silylenes with acetylenes and the dimerization of 1-silacyclopropenes

The addition of silylenes to acetylenes, and the dimerization of silacyclopropenes, are treated by Orbital Correspondence Analysis in Maximum Symmetry (OCAMS). The products observed in the latter reaction are consistent with an allowed pathway, a b_1g displacement involving rotation of the silacyclopropene molecules relative to one another in the transition state.     

Reaction of functionalized azomethine ylides with acetylenic dipolarophiles: the facile synthesis of functionalized 2H- and 1H-pyrroles

The reaction of functionalized azomethine ylides as C-unsubstituted nitrile ylide equivalents with acetylenic dipolarophiles is mentioned. Therein, the initially formed cycloadducts, 2,5-dihydropyrroles, by the reaction of the azomethine ylides with substituted acetylenes, undergo a fission reaction to afford 2H-pyrroles and the parent heterocyclic system. Some 2H-pyrroles isomerized to 1H-pyrroles under both thermal and acidic conditions.     

Efficient one-pot method for the synthesis of bis-propargylamines by the reaction of terminal acetylenes with 1,5,3-dioxazepanes catalyzed by cоpper chloride

An efficient method for the synthesis of N-substituted bis-propargylamines and bis(alkadiynyl)amines was developed. The method consists of the CuCl-catalyzed aminomethylation of terminal acetylenes and α,ω-diacetylenes with N-substituted 1,5,3-dioxazepanes.     

cis-Carbocuperation of acetylenic sulfoxides and corresponding applications in the regio- and stereoselective synthesis of polysubstituted vinyl sulfoxides

cis-Carbocuperation reaction of monoorganocopper reagent with acetylenic sulfoxides, followed by electrophilic reaction with a variety of electrophiles, provided a regio- and stereoselective method to prepare the versatile polysubstituted vinyl sulfoxides. Sonogashira cross-coupling reaction of the obtained α-iodovinyl sulfoxides with terminal acetylenes was also investigated to afford the versatile conjugate sulfinyl enynes.