14370-82-2

Allylic and propargyl bromides react smoothly with diorganyl diselenides in aqueous media to give allylic and propargyl selenides in moderate in good yields. The reaction need not he carried out in inert atmosphere. The speed is quicker than the same reactions in organic media.

-

A simple and efficient procedure for the synthesis of unsymmetrical diorganyl selenides from an one-pot indium(III) catalyzed procedure, in the presence of zinc, has been developed. Various organic halides and even the unreactive organic chlorides underwe

-

Allyl sulfides and allyl selenides are synthesized via the reaction of allyl bromide with disulfides and diselenides promoted by the Sm-BiCl3 system in aqueous media in moderate to good yields.

Figure presented A new approach for the synthesis of diorganyl selenides is described. By using economically attractive zinc dust in BMIM-BF4, a series of diorganyl selenides were efficiently achieved in excellent yields, under neutral reaction conditions. Compared to the usual organic solvents, BMIM-BF4 exhibited higher performance with the advantage to be reused up to five successive runs.

Selenofuran derivatives were prepared using several phenyl alkenyl selenides via seleno-Claisen rearrangement.

Palladium pincer-complex-catalyzed selenylation of propargyl-, allyl-, benzyl-, and benzoyl halides could be achieved under mild reaction conditions employing trimethylstannylphenylselenide as selenylating agent. This reaction has a high functional group

A new and convenient one-pot method for the preparation of unsymmetrical selenides has been developed. In the presence of cesium hydroxide, molecular sieves, and DMF, benzeneselenol undergoes direct alkylation with various alkyl halides for the synthesis of alkyl phenyl selenides in moderate to excellent yields. Another method to prepare unsymmetrical organoselenides was also completed by coupling terminal alkynes with benzeneselenyl bromide. As an application, the synthesis of a selenopeptide was also accomplished. Furthermore, this methodology was extended to the synthesis of an organoselenide on solid support.

Promoted by indium, allylic and propargyl bromides react with diorganyl diselenides in THF to give allylic and propargyl selenides in moderate to good yields.

The insertion of elemental selenium into the Zn-C bond of allylzinc bromide in THF leads to the corresponding zinc allyl selenoate. It reacts with diaryliodonium salts in THF-HMPA to afford the allyl arylselenides in high yields.

An efficient one-pot route to unsymmetrical diorganyl selenides has been developed by ruthenium-(III) chloride catalyzed reactions of dibenzyl or diphenyl diselenides with alkyl halides in the presence of zinc. Organic iodides, bromides, and activated chlorides underwent the reactions efficiently. Unreactive organic chlorides also underwent the same type of selenation with sodium bromide as the additive.

Promoted by metallic cadmium which was produced by reduction of CdCl2 · H2O with samarium in situ, allyl bromide and α -bromocarboxylates react with diorgano diselenides in aqueous solutions to give allylic-type selenides and α -selenocarboxylates in moderate to good yields.

A study by our laboratory shows that air, light and moisture stable O-(tert-butyl) Se-phenyl selenocarbonate could be employed as a safer, practical and efficient alternative to generate “in situ” benzeneselenol or benzeneselenolate anion under different and transition metal-free conditions. This procedure seems to be of general application since the nucleophilic selenium species obtained can be trapped by electrophiles such as alkyl halides, epoxides and electron-deficient alkenes and alkynes under different reaction conditions.

An air-stable μ-oxo-bridged binuclear Lewis acid of titanium(IV) salophen perfluorobutanesulfonate [{Ti(salophen)H2O}2O][OSO2C4F9]2 (1) was successfully synthesized by the reaction of TiIV(salophen)Cl2 with AgOSO2C4F9 and characterized by techniques such as IR, NMR and HRMS. This complex was stable open to air over a year, and exhibited good thermal stability and high solubility in polar organic solvents. The complex also had relatively strong acidity with a strength of 0.8 Ho ≤ 3.3, and showed high catalytic efficiency towards various C–S and C–Se bond formations in the presence of zinc power. This catalytic system affords a mild and efficient approach to synthesis of thio- and selenoesters, α-arylthio- and seleno-carbonyl compounds, and thio- and selenoethers.

The rearrangement of selenium ylides is even today almost unexplored, although it would provide access to important organoselenium compounds with broad downstream applications. In this report, the first systematic study of sigmatropic rearrangement reactions of selenium ylides using a simple rhodium catalyst with catalyst loadings as low as 0.01 mol % is described. Selenium oxide pyrolysis of the rearrangement products gives access to important 1,1-disubstituted butadienes.

A metal-free cleavage of diphenyl disulfide and diphenyl diselenide has been achieved using ionic liquid/triphenyl phosphine (PPh3) and a convenient protocol for the one-pot synthesis of unsymmetrical sulfides and selenides by condensing 'in situ' generated thiolate or selenate anion with alkyl halides has been developed. In addition, 1,4-conjugate addition of the generated thiolate anions to activated alkenes has also been demonstrated. The ionic liquid, 1-methyl-3-pentyl imidazolium bromide, [pmIm]Br plays a crucial role in promoting the course of the reactions and shows superior activity and selectivity compared to other solvents. The [pmIm]Br has been reused for at least five times without appreciable loss of activity.

A straightforward and efficient methodology is described to synthesize structurally diverse diorganyl selenides, sulfides, seleno- and thioesters by using commercially available Zn dust in ionic liquid. Excellent yields were achieved under neutral conditions at room temperature in a short time. The solvent/ionic liquid is reusable and exhibited higher performance as compared with organic solvents.

A fast and efficient phenylselenylation of allyl acetates by diphenyl diselenide and indium(i) bromide has been achieved in neat under the catalysis of Ru(acac)3. The intermediate complex of diphenyl diselenide and indium has been isolated and identified as a polymeric pentacoordinated In(iii) selenolate complex, [In(SePh)3]n.

-

The bimetallic reagent Sn(II)/Cu(II) in [bmim]BF4 was efficiently used for the cleavage of diaryl diselenides and disulfides and reacts with a variety of organic substrates, such as organic halides, acid chlorides, and β-amino mesylates affording the diorganyl selenides and sulfides within very short reaction times, under mild conditions and with excellent yields, using BMIM-BF4 as a reusable solvent.

(Figure Presented) Alumina-supported copper sulfate efficiently catalyzes electrophilic substitution in organoborane, organosilanes, and organostannanes by phenylselenium bromide providing a novel and efficient route to the synthesis of unsymmetrical diaryl and alkyl aryl selenides. A series of aryl, alkyl, and heteroaryl phenyl selenides were obtained in high yields. The catalyst is inexpensive, eco- and user-friendly, and recyclable. The mechanism involving Cu-assisted nucleophilic displacement of Br in PhSeBr by mild nucleophiles is described.

In an environmentally friendly protocol, InI was used as a reducing agent for the Se-Se bond to prepare unsymmetrical diorganyl selenides with very short reaction times, mild conditions and excellent yields using (bmim)BF4 as a recyclable solvent.

The optically active hydroxyphenylselenides derived from the p-menthane, carane, and pinane systems have been obtained. Two methods of hydroxyphenylselenides synthesis have been compared. The first method is based on the reaction of alkenes with N-(phenylseleno)succinimide in the presence of water, and the second from epoxides as a result of the reaction with sodium benzeneselenolate. The influence of the substrate structures on the composition of the obtained products has been demonstrated.

A convenient and efficient method was developed for the synthesis of alkyl phenyl selenides, sulfides, and selenoesters in one-pot reaction by using indium metal. The reaction showed the selectivity for tert-alkyl, benzylic, and allylic halides over primary and secondary alkyl halides. For the reaction of primary and secondary alkyl iodides and bromides, the yields of selenides were improved by the addition of a catalytic amount of iodine.

The reactivity of indium(III) benzenechalcogenolates (chalcogen = sulfur, selenium) towards organyl halides (organyl = alkyl, allyl, benzyl, acyl) was examined. A practical one-pot method to prepare organyl phenyl chalcogenides indium metal and diphenyl dichalcogenide was found. The coupling is fairly broad in scope and generally works better organyl halides capable to produce stable carbocations.

The 1-(organoselanyl)perfluoroalkanols 1, 3, 4, and 10 were successfully prepared and reactions with hexanoyl chlorides to produce the corresponding esters 5, 7, and 8, accompanied by the selenoesters 6 were conducted. The DBU-mediated alkylations of the heptafluorobutanols 4, 10, and the α-p-nitro-benzoate 2 with alkyl halides easily provided alkyl phenyl selenides 9a-9i and 11a-11c in good to high yields. Copyright

This communication details the Pd-catalyzed decarboxylation of selenocarbonates; use of a chiral nonracemic catalyst affords enantioenriched allyl selenides which undergo stereospecific [2,3]-sigmatropic rearrangements to form enantioenriched allylic amines and chlorides. The Royal Society of Chemistry.

(Chemical Equation Presented) Primary photochemical paths of alkyl phenyl selenides (1) were investigated, and an origin of large deviations in the chemical yields of products obtained by carbon radical reactions induced by photolysis of phenyl selenides was clarified. KrF excimer laser photolyses of n-pentyl phenyl selenide (1a) yielded 1-pentene (2a), n-pentane (3a), n-decane (4a), dipentyl selenide (5a), benzene (6), dipentyl diselenide (7a), and diphenyl diselenide (7) as major photoproducts, with compounds 2a, 3a, 4a, 5a, and 7 formed by pentyl-Se bond cleavage, and 5a, 6, and 7a by Ph-Se bond cleavage. The selectivity of the photoproducts revealed the occurrence of an unexpected amount of Ph-Se bond cleavage (35% in n-hexane at 248 nm) during photolysis. Solvent viscosity, wavelength of light, and the structure of alkyl substituents were the major factors that controlled Ph-Se bond cleavage. The ratio of Ph-Se bond cleavage decreased with increasing solvent viscosity and laser wavelength. The effect of alkyl substituents on the ratio of bond cleavages, Ph-Se/total C-Se, was investigated for five alkyl phenyl selenides; the ratio decreased in the order pentyl > 2-methylallyl > allyl > 1-ethylpropyl > tert-butyl groups. The contribution of Ph-Se bond cleavage is most probably the origin of the large deviations in the yields of radical reactions induced by photolyses of 1, which can be minimized by selecting appropriate solvents and wavelength of light.

The scandium-catalyzed reactions of α-organosulfanyl and organoselanyl-α-fluoroacetates 1-2, acetamides 3-4 and acetonitrile 5 with soft nucleophiles proceeded to give the products 6a-b, 7a-c, 8a-c, 9a-e in good to high yields. We also successfully perfor

A mild and convenient one-pot process for synthesizing alkyl phenyl selenides is developed using indium metal. The reaction shows the selectivity for tert-alkyl, benzylic, and allylic halides over primary and secondary alkyl halides.

The Sm/NiCl2 or Sm/NiCl2.6H2O system promoted diarylselenides to react with alkyl halides to afford unsymmetrical aryl selenides in good yields under mild and neutral conditions.

Promoted by Sm/cat. CoCl2 system, the Se-Se bond of diaryldiselenides was easily cleaved to form a "living" intermediate, which reacted readily with alkyl halides to afford unsymmetrical alkylarylselenides in good yields under mild and neutral reaction conditions.

We report a mild 1,3-dipolar cycloaddition protocol for the preparation of 3-aryl-5-phenylselenomethyl isoxazoles and isoxazolines regioselectively. The former was further reacted with LDA and electrophilic substrates followed by selenoxide syn-eliminatio

Diphenyl diselenides and disulfides undergo facile cleavages by indium(I) iodide and the corresponding generated selenate and thiolate anions condense in situ with alkyl or acyl halides present in the reaction mixture. Thus, a simple, efficient, and general procedure has been developed for the synthesis of unsymmetrical diorganyl selenides, sulfides (thioethers), selenoesters, and thioesters by this one-pot reaction at room temperature.

(Matrix presented) A simple and efficient procedure has been developed for the synthesis of unsymmetrical diorganyl selenides through a one-pot indium(I) iodide-mediated reaction of alkyl halide and diphenyl diselenide in methylene chloride at room temperature.

A convenient synthetic method of unsymmetrical selenides has been developed. When diphenyl diselenide was allowed to react with two equimolar amounts of primary alkyl iodides and bromides in the presence of an equimolar amount of lanthanum metal, alkyl ph

Organic halides of different structural types react with diphenyl diselenide and zinc dust in aqueous medium to give alkyl phenyl selenides. Benzylic and allylic bromides, α-bromoesters, acids and ketones and some primary alkyl iodides produce high yields even under acidic conditions. Less reactive halides need basic medium. The reaction proceeds equally well in the presence of various unprotected functional groups. Control experiments support a SH2 mechanism via alkyl radicals.

In the presence of chlorotrimethylsilane, ytterbium metal can promote the allylation of diselenides with allyl bromide to give the corresponding allylic selenides in good yields under mild and neutral conditions.

Arylseleninylacetates underwent facile α-functionalization on treatment with trimethylsilyl- or tri-n-butylstannyl-masked nucleophiles and trifluoroacetic anhydride (TFAA) or a Lewis acid. (C) 2000 Elsevier Science Ltd.

Alkylation and selenenylation of selenium-stabilized ester enolates have allowed the preparation of α-phenylselanyl esters 5, 7, 8 and of α,α-bis(phenylselanyl)esters 6, respectively. The competitive selenophilic reaction, leading to an allylic phenylselenide 9, was avoided in the presence of HMPA. α-phenylselanyl α,β-unsaturated esters 15 were prepared by oxidation of compounds 6 and dehydrohalogenation of β-chloroesters 17. Some other transformations: oxidation, transesterification and Grignard reaction were also studied. H2O2 oxidation of Z-esters 15 has led to stable E-α-seleninyl esters 20. (C) 2000 Elsevier Science Ltd.

Allylic and prop-2-ynyl (propargyl) bromides react with diorganyl diselenides in the presence of water to give allylic and prop-2-ynyl selenides in moderate to good yields; the reaction rate is faster than for the same reaction in anhydrous organic media.

-

α-Phenylselanyl γ-unsaturated ketones were obtained through allylation of enolates generated by potassium t-butoxide cleavage of β-phenylselanyl silyl enol ethers derived from α-phenylselanyl ketones. With enoxysilanes prepared from α-phenylselanyl aldehydes, O-allylation and O-benzylation of the corresponding enolates were also observed.

Allyl-propenyl rearrangement (prototropic isomerization) occurs in the synthesis of allyl organyl chalcogenides in a hydrazine hydrate - KOH system with a 6 - 10-fold molar excess of KOH. Specificities of the rearrangement that depend on the nature of the chalcogen were studied.

On the basis of preferential complexation of oxygen or selenium atoms by different Lewis acids, it was expected that, depending on the Lewis acid employed, the title reactions would lead to selective formation of homoallyl ethers or homoallyl selenides.This has not been confirmed by experiment: in almost all the reactions tried homoallyl ethers largely predominated, or were the exclusive allylation products, even when strongly oxygenophilic Lewis acids such as TiCl4 were used.In the cases of the latter type of Lewis acids, the results observed with (O,Se) and a couple of (O, S) mixed acetals are interpreted in terms of two major factors operating in opposite directions. 1H NMR data of a mixture of TiCl4 and (O,Se) acetal indicate that preferential (but not exclusive) complexation of the oxygen moiety takes place indeed.However, because of the much stronger C-O bond as compared to the C-Se bond, this latter (also activated by the Lewis acid to some extent) undergoes cleavage by allyl metals to give homoallyl ethers as predominating products.In contrast with BF3*OEt2, boron trichloride and boron tribromide were found to react with (O, Se) acetals to give the corresponding α-halo selenides, which in turn were cleanly transformed into homoallyl selenides on reaction with allyltrimethylsilane in the presence of tin tetrachloride.

In the presence of a catalytic amount of dichlorotris(triphenylphosphine)ruthenium(II), the reactions of arenesulfonyl chlorides with allyl phenyl sulfide and allyl phenyl selenide proceeded smoothly to give allyl phenyl sulfone in high yield as well as the corresponding diphenyl disulfide or diphenyl diselenide.An SH2'-type mechanism involving the arenesulfonyl radical is proposed.

Allylic phenyl selenides are prepared efficiently from the reaction of allylic acetates and diphenyl diselenide induced by samarium(II) diiodide in the presence of a palladium catalyst under mild conditions.

Compounds of the type CH2=CHCH2MR3 and (E)-PhCH=CHMR3 (M = Si, Ge, Sn, Pb) were allowed to react with a series of heteroatom-centered radicals (PhY*, Y = S, Se, Te, derived from PhYYPh) and carbon-centered radicals ((CH3)2CH* derived from (CH3)2CHHgCl).We report that alkenylplumbanes and, under forcing conditions, alkenylgermanes undergo SH2 or SH2' substitution of the metal by chain mechanism analogous to those previously reported for alkenylstannanes.Alkenylsilanes are unreactive.Based solely upon product yields, the following trends were observed: The reactivity of the alkenylmetals follow the order metal = Pb > Sn > Ge (> Si).The allylmetals were more reactive then the β-metallostyrenes toward the reactants employed in this study.The chalcogen series PhYYPh exhibits the reactivity order Y = S > Se > Te.

Reagents for the allylation of carbon radicals derived from the esters (mixed anhydrides) of N-hydroxy-2-thiopyridone have been investigated.Because of competition between the background reaction of decarboxylative rearrangement and the desired allylation process, conventional allylation reagents give moderate yields of the desired adducts.Improved yields are secured if the β-position bears an electron withdrawing group.A concerted addition and elimination process can be postulated.

Oxidative rearrangement of allylic selenides in the presence of various amine nucleophiles provides synthetic access to a variety of allylic amine derivatives.The stereochemical outcome of these reactions has been investigated, and is consistent with a -sigmatropic rearrangement mechanism.Several D-α-amino acids and racemic β,γ-unsaturated α-amino acids were prepared in this manner.A variant of this process employing an achiral allylic selenide and chiral amide afforded protected allylic amines in low diastereoisomeric excess.