Alkynyl Selenides Research Articles

Synthesis of Selenocyanates and Selenoethers of Amino Pyrazoles and Amino Uracils by In Situ Triselenium Dicyanide from Malononitrile and Selenium Dioxide.

Herein, we report an efficient method for synthesis of novel selenocyanates of amino pyrazole, amino uracil, and amino isoxazole derivatives using in situ triselenium dicyanide from the combination of malononitrile and selenium dioxide in DMSO medium. Using the same combination but changing the stoichiometry of reagents and sequence of addition and temperature, symmetrical selenoethers of amino pyrazoles and amino uracils were prepared in good yields. Furthermore, selenocyanates of amino pyrazoles were utilized for the synthesis of corresponding alkynyl selenides in the presence of CuI and Cs2CO3. The salient features of this methodology are inexpensive starting materials, short reaction time, and good to very good yields. This method is also applicable for the gram-scale synthesis of selenocyanates of amino pyrazoles and amino uracils.

Synthesis of Alkynylselenides under Visible-Light Irradiation Using the Ionic Liquid [BMIm]BF4 as a Solvent

In this work, a visible-light-driven synthesis of alkynyl selenides using [BMIm]BF4 as an environmentally friendly solvent and without the addition of metal catalysts, photosensitizers, directing-groups, or bases is reported. The target compounds were obtained in moderate to good yields with good functional group tolerance by the reaction of diorganoyldiselenides with 1-bromoalkynes proceeding through a radical mechanism.

Synthesis of novel alkynyl imidazopyridinyl selenides: copper-catalyzed tandem selenation of selenium with 2-arylimidazo[1,2-a]pyridines and terminal alkynes.

Alkynyl selenides have attracted considerable research interest recently, owing to their applications in the biological and pharmaceutical fields. The Cu-catalyzed tandem reaction for the synthesis of novel alkynyl imidazopyridinyl selenides is presented. A one-pot synthesis route afforded alkynyl imidazopyridinyl selenides in moderate to good yields. This was achieved by a two-step reaction between terminal alkynes and diimidazopyridinyl diselenides, generated from imidazo[1,2-a]pyridines and Se powder, using 10 mol % of CuI and 1,10-phenanthroline as the catalytic system under aerobic conditions. The C(sp2)–Se and C(sp)–Se bond-formation reaction can be performed in one-pot by using inexpensive and easy to handle Se powder as the Se source. The reaction proceeded with terminal alkynes having various substitutions, such as aryl, vinyl, and alkyl groups. The obtained alkynyl imidazopyridinyl selenide was found to undergo nucleophilic substitution reaction on Se atom using organolithium reagents and 1,3-dipolar azide–alkyne cycloaddition based on the alkyne moiety.

Copper‐Catalyzed Decarboxylative Alkylselenation of Propiolic Acids with Se Powder and Epoxides

AbstractA copper‐catalyzed decarboxylative alkylselenation of propiolic acids with Se powder and epoxides leading to alkynyl selenides is developed. This protocol not only provides an approach to obtain alkynyl selenides with the formation of double C−Se bonds, but also expands the applicability of alkynyl carboxylic acid.magnified image

A Benzoyl Peroxide/Diphenyl Diselenide Binary System for Functionalization of Alkynes Leading to Alkenyl and Alkynyl Selenides.

Binary systems consisting of benzoyl peroxide (BPO) and diorganyl diselenide are effective in the selective benzoyloxyselenation of internal alkynes to afford the corresponding β-(benzoyloxy)alkenyl selenides in good yields. In contrast to internal alkynes, terminal alkynes undergo a novel C(sp)-H substitution with the phenylseleno group of the BPO/(PhSe)2 system, providing alkynyl selenides in good yields. Both selenation reactions might proceed via benzoyloxy selenide (PhC(O)O-SeAr) as a key intermediate for electrophilic addition to alkynes. The products alkenyl and alkynyl selenides are expected to be useful synthetic intermediates in organic synthesis.

Synthesis of Alkynyl Selenides by Gold Tribromide Catalyzed Reaction of Terminal Alkynes with Diaryl Diselenides

Synthesis of Alkynyl Selenides by Gold Tribromide Catalyzed Reaction of Terminal Alkynes with Diaryl Diselenides

Transition-metal-free one-pot synthesis of alkynyl selenides from terminal alkynes under aerobic and sustainable conditions.

Alkynyl selenides were synthesized by a straightforward one-pot and three-step methodology, without the need of diselenides as starting reagents, under an oxygen atmosphere and using PEG 200 as the solvent. This procedure involves the in situ generation of dialkyl diselenides through a K3PO4-assisted reaction of an alkyl selenocyanate obtained by a nucleophilic substitution reaction between KSeCN and alkyl halides. Successive reaction with terminal alkynes in the presence of t-BuOK affords the corresponding alkyl alkynyl selenide in moderate to good yields. Finally, this methodology allowed the synthesis of 2-alkylselanyl-substituted benzofuran and indole derivatives starting from convenient 2-substituted acetylenes.

Copper‐Silver Dual Catalyzed Decyanative C–Se Cross‐Coupling

AbstractTraditionally, a metal‐catalyzed cross‐coupling reaction is governed by displacement of leaving groups such as halogens, tosylates, etc. by different nucleophiles leading to the formation of carbon‐carbon and carbon‐heteroatom bonds. Besides displacement of traditional leaving groups in coupling reactions decyanative cross‐coupling has also received current attention. The objective of this work is to develop a decyanative cross‐coupling through metal‐assisted nucleophilic displacement, which is less explored so far. Thus, a decyanative cross‐coupling of aryl selenocyanate with aryl‐/alkylacetylenes, boronic acids and silanes has been accomplished by a copper‐assisted nucleophilic displacement reaction for an easy access to a series of diaryl, aryl alkyl, aryl vinyl and aryl alkynyl selenides. The best yield of product was obtained using 5 mol% of Cu(OAc)2, Ag2CO3 (20 mol%) and Cs2CO3 (1 equiv.) at 100 °C for 8 h in N‐methylpyrrolidinone (NMP). The advantages of simple operation, high yields and general applicability make this procedure more attractive. A mechanistic pathway has been proposed. Silver plays a key role in the decyanation process. A plausible mechanistic pathway of this decyanative carbon‐selenium cross‐coupling has been proposed based on UV, EPR, HR‐MS and IR analytical data along with results obtained from control experiments.magnified image

Alkynylthioimidazolium Salts: Efficient Reagents for the Synthesis of Alkynyl Sulfides by Electrophilic Thioalkynylation.

The efficient synthesis of a series of alkynylthioimidazolium salts through reaction of organozinc compounds with dibromo(imidazolium)sulfuranes is reported. Addition of Grignard reagents to these new species provided a highly modular, clean, and scalable access to a broad variety of alkynyl sulfides in good-to-excellent yields. The utility of this protocol was showcased by the preparation of alkynyl sulfides, which are particularly difficult to obtain or simply unavailable through the existing methodologies. In addition, the synthetic method was extended to the preparation of alkynyl selenides.

Mechanochemical Synthesis of Active Magnetite Nanoparticles Supported on Charcoal for Facile Synthesis of Alkynyl Selenides by C−H Activation

AbstractMagnetite (Fe3O4) nanoparticles supported on charcoal, graphene, or SBA‐15 were prepared by a simple solid‐state grinding technique and subsequent thermal treatment. The Fe3O4 nanoparticles supported on activated charcoal exhibited high catalytic activity and furnished good yields of the alkynyl selenide product in the cross‐coupling reaction of diphenyl diselenide and alkynes through activation of C−H and Se−Se bonds under ecofriendly conditions, surpassing traditional copper‐based catalysts to effect the same organic transformation.

ChemInform Abstract: Broensted Acid Catalyzed Intramolecular Hydroarylation for the Synthesis of Cycloalkenyl Selenides and Tellurides.

AbstractThe reaction of alkynyl selenides and tellurides is catalyzed by TfOH and affords the intramolecular hydroarylation products, occurring in a selective 6‐ and 7‐endo‐mode.

Brønsted Acid Catalyzed Intramolecular Hydroarylation for the Synthesis of Cycloalkenyl Selenides and Tellurides

AbstractTrifluoromethanesulfonic acid catalyzed intramolecular hydroarylation of alkynyl selenides and tellurides is developed for the preparation of cycloalkenyl selenide and telluride derivatives through a selective 6‐ and 7‐endo mode. The cycloalkenyl selenides and tellurides can be easily converted into a wide range of other valuable functionalities, including cyclic olefins, allylic alcohols, enynes, 1,3‐dienes, and α,β‐unsaturated aldehydes.

ChemInform Abstract: A Simple and Effective Approach to the Synthesis of Alkynyl Selenides from Terminal Alkynes.

Alkynyl selenides were prepared under very mild conditions by reacting terminal alkynes with respective diorganic diselenides in the presence of potassium t-butoxide. The advantages of this protocol include the use of readily available substrates and reagent and good yield of the products.

An efficient and general procedure for the synthesis of alkynyl chalcogenides (selenides and tellurides) by alumina-supported Cu(II)-catalyzed reaction of alkynyl bromides and diphenyl dichalcogenides

Alumina (Al2O3) supported Cu(II) efficiently catalyzes the reaction of alkynyl bromides and diphenyl diselenides and ditellurides in presence of Zn dust or indium(I) bromide to provide the corresponding alkynyl selenides and tellurides. The reactions of a wide variety of substituted alkynyl bromides have been addressed. The zinc dust or InBr is required for the cleavage of diphenyl selenides/tellurides. The mechanism of the reaction is established. The yields of products are high and the catalyst is recycled.

An efficient synthesis of alkynyl selenides and tellurides from terminal acetylenes and diorganyl diselenides or ditellurides catalyzed by recyclable copper oxide nanopowder

Herein, we report an efficient method for the synthesis of alkynyl selenides and tellurides from terminal alkynes and diorganyl diselenides or ditellurides using CuO nanopowder as a recyclable catalyst. This new methodology furnished the desired products in good to excellent yields. Furthermore, the catalyst was easily recovered and reused for further catalytic reactions without loss of activity.

A simple and effective approach to the synthesis of alkynyl selenides from terminal alkynes

Alkynyl selenides were prepared under very mild conditions by reacting terminal alkynes with respective diorganic diselenides in the presence of potassium t-butoxide. The advantages of this protocol include the use of readily available substrates and reagent and good yield of the products.

ChemInform Abstract: Cesium Hydroxide Catalyzed Hydrothiolation of Alkynyl Selenides to Highly Stereo‐ and Regioselectively Synthesize (Z)‐1‐Organoseleno‐2‐arylthio‐1‐alkenes.

In the presence of catalytic amount of cesium hydroxide the hydrothiolation of alkynyl selenides occurred at room temperature in DMF under nitrogen atmosphere to give exclusive (Z)-1-organoseleno-2-arylthio-1-alkene in excellent yields. It could provide a new and expedient way for the preparation of (Z)-1-arylseleno-2-arylthio-1-alkene.

Cesium hydroxide-catalyzed hydrothiolation of alkynyl selenides to highly stereo- and regioselectively synthesize (Z)-1-organoseleno-2-arylthio-1-alkenes

In the presence of catalytic amount of cesium hydroxide the hydrothiolation of alkynyl selenides occurred at room temperature in DMF under nitrogen atmosphere to give exclusive (Z)-1-organoseleno-2-arylthio-1-alkene in excellent yields. It could provide a new and expedient way for the preparation of (Z)-1-arylseleno-2-arylthio-1-alkene.

ChemInform Abstract: [2 + 2] Cycloaddition Reactions of Imines with Alkynyl Selenides Catalyzed by Scandium Triflate.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Palladium-catalyzed alkynylselenation of acetylenedicarboxylates leading to enyne selenides and application to synthesis of multisubstituted aryl selenides

Abstract Upon treatment of a mixture of alkynyl selenides and acetylenedicarboxylates with Pd(OAc) 2 /P( o -tol) 3 /K 2 CO 3 /H 2 O-catalytic system, the alkynylselenation of acetylenedicarboxylates takes place to give the corresponding alkynylvinyl selenides. Furthermore, alkynyl selenides undergo the intermolecular [2+2+2] cycloaddition reaction in the presence of PdCl 2 (PPh 3 ) 2 as a catalyst, affording the corresponding multisubstituted aryl selenides selectively.