- Metal-Free Synthesis of Selenodihydronaphthalenes by Selenoxide-Mediated Electrophilic Cyclization of Alkynes
-
A transition-metal-free, selenium mediated electrophilic cyclization reaction was realized through a one-pot procedure between simple alkynes and triflic anhydride-activated selenoxides to give selenium containing dihydronaphthalene products. This method gave good to very high yields for all products, including selenium-substituted phenanthrene, dihydroquinoline, 2H-chromene, and coumarin, which can be further transformed to other functionalized compounds.
- An, Shaoyu,Li, Pingfan,Zhang, Zhong
-
p. 3059 - 3070
(2021/07/22)
-
- Synthesis and Reactivity Studies of a Series of Nickel(II) Arylchalcogenolates
-
Two series of high-spin nickel complexes, [TpPh,Me]Ni(EAr) (E = O, Se, Te; Ar = C6H5) and [TpPh,Me]Ni(SeC6H4-4-X) (X = H, Cl, Me, OMe), were prepared by metathetical reaction of the nickel(II) halide precursor with sodium salts of the corresponding chalcogen, NaEAr. X-ray crystallographic characterization and spectroscopic studies have established the geometric and electronic structures of these complexes. The observed spectroscopic and structural characteristics reveal distinct trends in accordance with the variation of the identity of the arylchalcogenolate and para substituent. Reaction of the [TpPh,Me]Ni(EAr) complexes with methyl iodide proceeded readily, producing the corresponding methylarylchalcogen and [TpPh,Me]NiI. A kinetic and computational analysis of the reaction of [TpPh,Me]Ni(SeC6H5) with MeI supports that the electrophilic alkylation reactions occur via an associative mechanism via a classical SN2 transition state.
- Cordeiro, Lauren L.,Dmitrenko, Olga,Yap, Glenn P. A.,Riordan, Charles G.
-
p. 6327 - 6338
(2021/05/06)
-
- Corey-Chaykovsky Cyclopropanation of Nitronaphthalenes: Access to Benzonorcaradienes and Related Systems
-
Nitronaphthalene derivatives react as Michael acceptors in the Corey-Chaykovsky reaction with alkyl phenyl selenones and alkyl diphenyl sulfonium salts. Mechanistic studies reveal that sterically demanding substituents at the carbanionic center favor formation of cyclopropanes and suppress competitive β-elimination to the alkylated products. The transformation, demonstrated also on heterocyclic nitroquinoline and nitroindazolines, is an example of transition metal-free dearomatization method.
- Antoniak, Damian,Barbasiewicz, Micha?
-
supporting information
p. 9320 - 9325
(2019/11/19)
-
- 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.
- Heredia, Adrián A.,Pe?é?ory, Alicia B.
-
supporting information
p. 910 - 918
(2017/06/21)
-
- Effect of chalcogenyl substituent on the course of allyl rearrangement at chalcogenation of 1,3-dichloropropene
-
Formation of 1,3-dichalcogenylpropene at the treatment of 1,3-dichloropropene with organic dichalcogenides in a redox system hydrazine hydrate–KOH is governed by the possibility of an allyl rearrangement. In the presence of bases this rearrangement proceeds via carbanion partially stabilized by the chalcogenyl substituent. The effectivity of the stabilization and consequently the probability of the rearrangement varies in the series of substituents PhS > BnS > PhSe. In the stage of the direct nucleophilic substitution of chlorine the anion PhSe?possesses the highest activity.
- Levanova,Nikonova,Grabel’nykh,Russavskaya,Albanov,Rozentsveig,Korchevin
-
p. 615 - 623
(2016/07/06)
-
- Synthesis of unsaturated organoselenium compounds via the reaction of organic diselenides with 2,3-dichloro-1-propene in the hydrazine hydrate-KOH system
-
Dimethyldiselenide reacts with 2,3-dichloro-1-propene at 20-25 C in the hydrazine hydrate-KOH medium to form 2-chloro-3-methylselanyl-1-propene with 90% yield. Diphenyldiselenide in the reaction with 2,3-dichloro-1-propene, depending on the conditions, ca
- Levanova,Grabel'Nykh,Vakhrina,Russavskaya,Albanov,Klyba,Tarasova,Rozentsveig,Korchevin
-
p. 1660 - 1665
(2013/11/19)
-
- A general and green procedure for the synthesis of organochalcogenides by CuFe2O4 nanoparticle catalysed coupling of organoboronic acids and dichalcogenides in PEG-400
-
A general and efficient procedure has been developed for the synthesis of organochalcogenides (selenides and tellurides) by a simple reaction of organoboronic acids and dichalcogenides catalysed by CuFe2O 4 nanoparticles in PEG-400 without any ligand. This protocol offers the scope for access to a wide spectrum of chalcogenides including diaryl, aryl-heteroaryl, aryl-styrenyl, aryl-alkenyl, aryl-allyl, aryl-alkyl and aryl-alkynyl versions. The catalyst is magnetically separable and recyclable eight times without any loss of appreciable catalytic activity. The products are obtained in high purities after evaporation of solvent followed by filtration column chromatography. The Royal Society of Chemistry.
- Kundu, Debasish,Mukherjee, Nirmalya,Ranu, Brindaban C.
-
p. 117 - 125
(2013/04/10)
-
- Synthesis of arylselenide ethers by photoinduced reactions of selenobenzamide, selenourea and selenocyanate anions with aryl halides
-
Selenobenzamide (-SeCNH(Ph), 1), selenourea ( -SeCNH(NH2), 2) and selenocyanate (-SeCN, 3) anions afford areneselenolate ions (ArSe-) under photostimulation in the presence of tert-butoxide or 2-naphthoxide ions as electron donors (entrainment conditions) in DMSO. In a 'one-pot' procedure, ArSe- anions can be trapped by a subsequent aliphatic nucleophilic substitution giving aryl methyl selenides in good to excellent yields (67-100%). This simple approach is compatible with electron-donating and electron-withdrawing substituents, such as nitro and carbonyl groups.
- Bouchet, Lydia M.,Pe?é?ory, Alicia B.,Argüello, Juan E.
-
experimental part
p. 969 - 972
(2011/03/20)
-
- FeCl3-Diorganyl dichalcogenides promoted cyclization of 2-alkynylanisoles to 3-chalcogen benzo[ b ]furans
-
A general synthesis of 3-chalcogen benzo[b]furans from the readily available 2-alkynylanisoles, via FeCl3/diorganyl dichalcogenides intramolecular cyclization, has been developed. Aryl and alkyl groups directly bonded to the chalcogen atom were used as cycling agents. The results revealed that the reaction significantly depends on the electronic effects of substituents in the aromatic ring bonded to the selenium atom of the diselenide species. We observed that the pathway of reaction was not sensitive to the nature of substituents in the aromatic ring of anisole since both the electron-donating and the electron-withdrawing groups delivered the products in similar yields. In addition, the obtained heterocycles were readily transformed to more complex products by using a chalcogen/lithium exchange reaction with n-BuLi followed by trapping of the lithium intermediate with aldehydes, furnishing the desired secondary alcohols in good yields.
- Gay, Rafaela M.,Manarin, Flavia,Schneider, Caroline C.,Barancelli, Daniela A.,Costa, Michael D.,Zeni, Gilson
-
supporting information; experimental part
p. 5701 - 5706
(2010/10/03)
-
- Nucleophilic cleavage of lactones and esters with zinc selenolates prepared from diselenides in the presence of Zn/AlCl3
-
The utility of zinc selenolates for effecting nucleophilic cleavage of simple lactones and esters has been investigated. When zinc selenolate generated via Zn/AlCl3-promoted cleavage of diselenides was reacted with simple lactones and esters, efficient nucleophilic alkyl-oxygen bond cleavage proceeded generating the corresponding carboxylic acids in moderate to excellent yields.
- Nazari, Mohammad,Movassagh, Barahman
-
scheme or table
p. 438 - 441
(2009/05/27)
-
- 1-(organoselanyl)perfluoroalkanols: A stable and efficient precursor for organoselenols
-
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
- Yamamoto, Terahisa,Moriura, Eri,Sawa, Arisa,Yoshimatsu, Mitsuhiro
-
scheme or table
p. 1046 - 1047
(2009/12/03)
-
- A simple zinc-mediated preparation of selenols
-
Under acidic conditions zinc reduces diselenides to afford selenols, which can be either isolated or treated in situ with alkyl halides to produce alkyl selenides or with epoxides to give β-hydroxyselenides. Georg Thieme Verlag Stuttgart.
- Santi, Claudio,Santoro, Stefano,Testaferri, Lorenzo,Marcello Tiecco
-
scheme or table
p. 1471 - 1474
(2009/04/07)
-
- Convenient synthesis of unsymmetrical organochalcogenides using organoboronic acids with dichalcogenides via cleavage of the S-S, Se-Se, or Te-Te bond by a copper catalyst
-
(Chemical Equation Presented) This article describes the methodology for a copper-catalyzed preparation of numerous monochalcogenides from dichalcogenides with organoboronic acids. Unsymmetrical diorgano-monosulfides, selenides, and tellurides can be synthesized by the coupling of dichalcogenides with aryl- or alkylboronic acids using a copper catalyst in air. The present reaction can take advantage of both organochalcogenide groups on dichalcogenide.
- Taniguchi, Nobukazu
-
p. 1241 - 1245
(2007/10/03)
-
- Aqueous phase one-electron reduction of sulfonium, selenonium and telluronium salts
-
Triorganylsulfonium, -selenonium and -telluronium salts were reduced by carbon dioxide radical anions/solvated electrons produced in aqueous solution by radiolysis. The radical expulsion accompanying reduction occurred with the expected leaving group propensities (benzyl > secondary alkyl > primary alkyl > methyl > phenyl), although greater than expected loss of the phenyl group was often observed. Diorganyl chalcogenides formed in the reductions were conveniently isolated by extraction with an organic solvent. Product yields based on the amount of reducing radicals obtained from the γ-source were often higher than stoichiometric (up to 1800 %) in the reduction of selenonium and telluronium compounds; it is likely that this result can be accounted for in terms of a chain reaction with carbon-centred radicals/formate serving as the chain transfer agent. The product distribution was essentially independent of the reducing species for diphenyl alkyl telluronium salts, whereas significant variations were seen for some of the corresponding selenonium salts. This would suggest the intermediacy of telluranyl radicals in the one-electron reduction of telluronium salts. However, pulse radiolysis experiments indicated that the lifetimes of such a species (the triphenyltelluranyl radical) would have to be less than 1 μs. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.
- Eriksson, Per,Engman, Lars,Lind, Johan,Merenyi, Gabor
-
p. 701 - 705
(2007/10/03)
-
- Transformation of β-chalcogeno alkenylboranes into tetrasubstituted olefins
-
In view of generating trisubstituted vinylic chalcogen derivatives, β-chalcogeno alkenylboranes generated through the chalcogen electrophile induced rearrangements of 1-alkynyltrialkyl borates have been subjected to Suzuki-Miyaura coupling and to boron to copper transmetalation followed by alkylation. Some of the trisubstituted vinyl sulfides obtained by this latter strategy have been converted efficiently into the title olefins through the NiCl2(dmpe) catalyzed coupling with various Grignard reagents.
- Gerard, Julien,Hevesi, László
-
p. 367 - 381
(2007/10/03)
-
- A novel and highly efficient synthetic route to unsymmetrical organoselenides using cesium bases
-
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.
- Cohen, Richard J.,Fox, Daniel L.,Salvatore, Ralph Nicholas
-
p. 4265 - 4268
(2007/10/03)
-
- Synthesis of chalcogenides using indium intermediates in aqueous media
-
Selenides and vinylic selenides were synthesized from their corresponding organic halides and alkynes in aqueous media using indium metal.
- Galindo, Andréa C.,Oliveira, Juliana M.,Barboza, Maria A. G.,Gon?alves, Simone M. C.,Menezes, Paulo H.
-
p. 129 - 140
(2007/10/03)
-
- Rapid and precise preparation of reactive benzeneselenolate solutions by reduction of diphenyl diselenide with hydrazine-sodium methanolate
-
Solutions of sodium benzeneselenolate sufficiently reactive to effect 'aromatic substitution and ester dealkylation are prepared in DMSO or NMP from diphenyl diselenide and hydrazine hydrate by titration with methanolic sodium methanolate.
- Henriksen, Lars,Stuhr-Hansen, Nicolai
-
p. 1915 - 1916
(2007/10/03)
-
- Thermal reactions of organyl chalcogenides with α,β-unsaturated aldehydes
-
Thermalgas-phase reactions of acrolein, cinnamaldehyde, and benzaldehyde with diorganyl chalcogenides and diorganyl dichalcogenides were studied.Acrolein does not react with chalcogenides at 300-600 deg C but completely decomposes under reaction conditions.At 600-650 deg C, cinnamaldehyde reacts only with diorganyl selenides and diselenides to give benzoselenophene.Its highest yield (53percent) is achieved in the reaction with dimethyl diselenide at 630 deg C and at an equimolar ratio of the reactants.The gas-phase reactions of benzaldehyde at 400-500 deg C afford chalcogen-containing derivatives of several types, among which thioanisole and its selenium or tellurium analogs predominate.The mechanisms of the above reactions were discussed in terms of homolytic substitution of the formyl group at unsaturated carbon atoms by chalcogenyl radicals. - Keywords: gas-phase reactions; cinnamaldehyde; benzaldehyde; chalcogenyl radicals; benzoselenophene, selenoanisole, telluroanisole.
- Deryagina, E. N.,Korchevin, N. A.,Shilkina, T. A.,Sukhomazova, E. N.,Levanova, E. P.
-
p. 447 - 450
(2007/10/03)
-
- Carbonyl transposition on organoselenium compounds
-
Carbonyl conjugated vinylic selenides undergo 1,3 and 1,5-carbonyl transposition sequences through organometallic reagents addition reactions followed by acid hydrolysis.
- Comasseto, Joao V.,Lo, Wai L.,Petragnani, Nicola
-
p. 7445 - 7460
(2007/10/03)
-
- GENERATION OF CHALCOGENIDE ANIONS IN HYDRAZINE HYDRATE MEDIUM
-
Aromatic thiols and dichalcogenides in hydrazine hydrate are effective generators of chalcogenide ions that will react with organyl halides to form diorganyl chalcogenides.Alkanethiols and dialkyl dichalcogenides are less effective in reaction with organyl chalcogenides.
- Turchaninova, L. P.,Korchevin, N. A.,Deryagina, E. N.,Trofimov, B. A.,Voronkov, M. G.
-
p. 125 - 126
(2007/10/02)
-
- Syntheses of alkali selenolates from diorganic diselenides and alkali metal hydrides: Scope and limitations
-
Sodium and potassium alkane[arene]selenolates have been efficiently prepared from the corresponding diselenides using sodium or potassium hydrides in dimethylformamide or tetrahydrofuran. The reaction cannot be extended for the production of their lithium analogues nor for sodium and potassium phenylmethaneselenolates.
- Krief,Trabelsi,Dumont
-
p. 933 - 935
(2007/10/02)
-
- REDUCTION OF SULFONIUM AND SELENONIUM SALTS WITH SAMARIUM DIIODIDE
-
Treatment of sulfonium and selenium salts with 2 equiv of a THF solution of samarium diiodide caused the reductive cleavage of the C-S or C-Se bonds in high yields.The bond cleavage took place regioselectively between the positive sulfur or selenium atom and the carbon atom with an electron-withdrawing group or a vinyl group.Some medium-sized cyclic sulfides or selenides were synthesized by this method.
- Kataoka, Tadashi,Iwama, Tetsuo,Shimizu, Hiroshi,Hori, Mikio
-
p. 169 - 172
(2007/10/02)
-
- Synthesis of Medium-Sized Cyclic Sulfides and Selenides by Crosspiece C-X Bond Cleavage of Bicyclic Onium Salts Bearing a Bridgehead Sulfur or Selenium Atom
-
Medium-sized cyclic sulfides 5a-5h and selenides 5i-5k were synthesized by reductive C-X bond cleavage of bicyclic sulfonium 4a-4h and selenonium salts 4i-4k, respectively.Reducing agents used were magnesium metal, sodium borohydride and samarium diiodide.Samarium diiodide reduction of simple sulfonium and selenonium salts 11a-11d, 15-18 was also carried out.Application of this method to the C-S bond cleavage of sulfonium salts 25a and 25b provided sulfur-containing medium-sized lactams 26a and 26b, respectively, in high yields.Treatment of the sulfonium salts 4f and 4g with a base gave an olefinic sulfide 33 and a cyclopropane derivative 31, respectively.The stereochemistry of the sulfonium, 4d and 4e, and selenonium salts, 4j and 4k, is discussed on the basis of the 13C NMR spectral data.
- Kataoka, Tadashi,Iwama, Tetsuo,Tsutsumi, Kazuhiro,Nakamura, Yoshihide,Matsumoto, Harutoshi,et al.
-
p. 3153 - 3194
(2007/10/02)
-
- A New Method for Radical Generation: Reductive C-Se or C-S Bond Cleavage of Cyclic Onium Salts
-
2-Methyl-3,4-dihydro-1H-2-benzoselenopyranium salt (1) was reduced by some metallic reagents or magnesium metal via the single-electron transfer (SET) process to give 2--toluene (2).Magnesium metal was a good SET reducing agent.Some other selenonium or sulphonium salts (7), (14), (22), (27) and (32) were similarly reduced by magnesium.Particularly, sonication accelerated the reductions. ε-Eneselenonium salt (43) was treated with activated magnesium to give a cyclised pyrrolidine derivative (44).
- Kataoka, Tadashi,Tsutsumi, Kazuhiro,Kano, Kenji,Mori, Kazuya,Miyake, Miho,et al.
-
p. 3017 - 3025
(2007/10/02)
-
- SYNTHESIS OF α-SELENOALKYLLITHIUM COMPOUNDS
-
α-Phenylselenoalkyllithiums and α-methylselenoalkyllithiums have been prepared from the corresponding selenoacetals and alkyllithiums.Several features of this reaction are disclosed.For example, the reaction is more readily achieved on phenylselenoacetals than on methylseleno analogues.Those derived from hindered carbonyl compounds are less readily cleaved. s-BuLi/THF proved superior to n-BuLi in THF, itself better than n-BuLi in ether.
- Krief, A.,Dumont, W.,Clarembeau, M.,Bernard, G.,Badaoui, E.
-
p. 2005 - 2022
(2007/10/02)
-
- RADICAL C-Se BOND CLEVAVAGE OF SELENONIUM SALTS WITH GRIGNARD REAGENTS OR MAGNESIUM METAL
-
The reaction of 2-methylisoselenochromanium salt with Grignard reagents afforded the reductive ring-opened product by the single electron transfer (SET) mechanizm, not by the self-decomposition of ?-selenurane.The same reduction was observed in the reaction of the selenonium salt with magnesium metal.Some other selenonium salts were easily reduced by magnesium metal to give ring-opened products.
- Hori, Mikio,Kataoka, Tadashi,Shimizu, Hiroshi,Tsutsumi, Kazuhiro
-
p. 981 - 984
(2007/10/02)
-
- Aryl Arylazo Sulfones Chemistry. 2. Reactivity toward Alkaline Alkane- and Areneselenolate and Alkane- and Arenetellurolate Anions
-
Tolyl arylazo sulfones react with various alkyl- and arylseleno reagents to produce substituted alkyl aryl and unsymmetrical diaryl selenides.The corresponding tellurides can also be obtained.Isolated yields in both cases are good.This procedure is an interesting alternative to the classical Sandmeyer reaction.
- Evers, Michel J.,Christiaens, Leon E.,Renson, Marcel J.
-
p. 5196 - 5198
(2007/10/02)
-
- SYNTHESIS, STRUCTURE, AND PROPERTIES OF COMPOUNDS WITH A CHALCOGEN-NITROGEN BOND. V. N-TRIFLUOROACETYL-Se-ARYL-Se-METHYLSELENIMIDES
-
The IR and UV spectra of a series of N-trifluoroacetyl-Se-aryl-Se-methylselenimides were studied.The molecules of these compounds, like those of N-acylsulfimides and N-acyltelurimides with similar structures, have a bipolar structure, in which the negative charge is distributed through the bond system of the N-trifluoroacetyl group.
- Naddaka, V. I.,Krasnov, V. P.,Minkin, V. I.
-
p. 432 - 436
(2007/10/02)
-
- PHOTOSTIMULATED REACTIONS OF 1-IODOADAMANTANE AND IODOBENZENE WITH THIOLATE, SELENATE, AND TELLURATE IONS
-
The photostimulated reaction of 1-iodoadamantane (1-IAd) with benzenethiolate ion gave the substitution product 1-adamantylphenylsulfide.With benzeneselenate ion (PhSe-) it gave three products: diphenylselenide, 1-adamantylphenylselenide and di(1-adamantyl) selenide.With benzenetellurate ions it gave the substitution product 1-adamantylphenyltelluride and diphenyltelluride, the latter is ascribed to the photodecomposition of the nucleophile.The photostimulated reaction of 1-IAd with 1-naphtaleneselenate ion only gave the substitution product without scrambling of products.The photostimulated reaction of PhI with 1-adamantaneselenate ion gave the same three products as the reaction of 1-IAd and PhSe- ion, but with different ratios of products.The reaction with 1-adamantanetellurate ion gave mainly diphenyltelluride, together with the substitution product 1-adamantylphenyltelluride.The relationship of the fragmentation rates of Ad-Z and Ph-Z bonds in radical anions of structure (1-AdZPh). were studied, and kfAdZ/kfPhZ, being Z=S is 3.7, Z=Se is 9.5 and Z=Te is 13.These results suggest that in the photostimulated reactions the products obtained depend on the energy levels of the antibonding ?* MO and the ?* MO of the C-Z(Z=S, Se and Te) bonds of the radical anion intermediate.The fragmentation rates of the radical anion intermediates depend on the energy levels of the MO'S involved.
- Palacios, Sara M.,Alonso, Ruben A.,Rossi, Roberto A.
-
p. 4147 - 4156
(2007/10/02)
-
- Oxidation of Alkyl Phenyl Selenides, Tellurides, and Telluroxides with meta-Chloroperbenzoic Acid for a Facile and Novel Transformation of C-Se and C-Te Bonds to C-O Bonds
-
In sharp contrast to the well-known selenoxide elimination leading to olefins, the treatment of alkyl phenyl selenides (PhSeR) with an excess of meta-chloroperbenzoic acid (MCPBA; 2-5 equiv. to a selenide) in alcohol at room temperature affords the corresponding dialkyl ethers by the substitution of a phenylselenium (PhSe) moiety with an alkoxy group.A similar reaction proceeds by using alkyl phenyl tellurides (PhTeR) and telluroxides , a facile substitution of PhTe or PhTe(O) moiety by an alkoxy group being observed.Methanol is the most appropriate solvent for these oxidations and alkyl methyl ethers are formed in excellent yields.The reaction is accompanied by phenyl migration when applied to some selenides, tellurides, and telluroxides having a phenyl group at a vicinal position to the PhSe, PhTe, or PhTe(O) moiety.Application to the methoxyselenation and methoxytelluration products of cyclohexene and cycloheptene results in a ring-contraction to afford the dimethyl acetals of cyclopentane- and cyclohexane-carbaldehyde, respectively.In case of an allylic phenyl selenide, a sigmatropic rearrangement giving a rearranged allylic alcohol occurs in much preference to the substitution by the methoxy group.Other oxidizing agents than MCPBA such as NaIO4, H2O2, t-BuOOH, and ozone are generally ineffective under similar conditions.It is proposed that the reaction mainly takes place as follows.Alkyl phenyl selenone, alkyl phenyl tellurone, or the MCPBA addition product to them is formed as a reactive intermediate in which an alkyl C-Se or alkyl C-Te bond fission occurs heterolytically by a nucleophilic attack of alcohol, sometimes accompanied by a 1,2-shift of the β-substituent, i.e., phenyl migration and ring-contraction.
- Uemura, Sakae,Fukuzawa, Shin-ichi
-
p. 471 - 480
(2007/10/02)
-
- ASYMMETRIC OXIDATION OF ACHIRAL SELENIDES TO OPTICALLY ACTIVE SELENOXIDES. STEREOCHEMISTRY OF THE ALLYL SELENOXIDE-SELENENATE SIGMATROPIC REARRANGEMENT
-
Asymmetric oxidation of methyl phenyl selenide (3), under anhydrous conditions, by chiral 2-sulfonyloxaziridines, 1-2, give optically active methyl phenyl selenoxide (8.1-9.3percent ee).The stereochemistry of the selenoxide is determined by the configuration of the oxaziridine three membered ring with nonbonded steric interactions responsible for the chiral recognition.Asymmetric oxidation of E-phenyl cinnamyl selenide (7) by 1-2 affords optically active 1-phenylallyl alcohol (9).A concerted sigmatropic rearrangement via an exo transition state is proposed.
- Davis, Franklin A.,Stringer, Orum D.,McCauley, John P., Jr.
-
p. 4747 - 4758
(2007/10/02)
-
- Methyl Transfers. 10. The Marcus Equation Application to Soft Nucleophiles
-
The Marcus equation to methyl transfers is shown to cover reactions of " soft" nucleophiles, although small discrepancies occur.Rates and equilibria are reported for a series of reactions of arylmethylselenides with (p-chlorophenyl)dimethylselenonium ion.Experimental reaction rates between "hard" methylating agents and "soft" nucleophiles show small deviations from the calculated values, mostly but not always in the direction predicted by the HSAB principle.The Marcus equation fails to explain the previously reported "inversion" of reaction rates of 4-nitrothiophenoxide and of 4-nitrophenoxide with methyl iodide and dimethyl sulfate.Identity rates for dimethyl sulfate, methyl methanesulfonate (using 3He), methyl iodide (using 125I), and methyl triflate (using 35S) in sulfolane are reported.
- Lewis, Edward S.,McLaughlin, Mark L.,Douglas, Thomas A.
-
p. 6668 - 6673
(2007/10/02)
-
- TRIORGANOTIN ARYL SELENIDES
-
The Sn-Se bond in trimethyltin aryl selenides is cleaved on reaction with selenenyl halides, sulphenyl halides, alkyl halides and allyl halides.Thus Me3SnSePh reacts with PhSeCl, 4-Me-2-NO2C6H3SCl, RI (R = CH3 or Ph3SnCH2) and CH2=CHCH2Br to give PhSeSePh, 4-Me-2-NO2C6H3SSePh, RSePh and CH2=CHCH2SePh, respectively.The diselenide, PhSeSePh, is also obtained from Me3SnSePh on reaction with either 4-MeC6H4SO2Cl or NaIO4.Exchange reactions also occur between Me3SnSePh and Ph3SnCl or PhHgCl.
- Grant, Douglas W.,Wardell, James L.
-
p. 161 - 166
(2007/10/02)
-
- Nucleophilic Aromatic Substitutions of Unactivated Aryl Halides by Methyl Selenide Anions. Synthesis and Selective Dealkylations of Aryl Alkyl Selenides
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Lithium methyl selenide, easily prepared from powdered gray selenium and MeLi, reacts with unactivated aryl halides, in DMF, to afford the aryl methyl selenides as a result of a nucleophilic aromatic substitution.The aryl methyl selenides are rapidly dealkylated in the reaction medium by MeSeLi to give the aryl selenide anions.Addition of an alkyl halide or of cyanogen iodide gives rise to the formation of aryl alkyl selenides or aryl selenocyanates in good yields.From competitive experiments, carried out on compounds of the type ArClSeR and ArClSR, it has been shown that an RSe group is as efficient as an RS group in activating the nucleophilic aromatic substitution of a chlorine atom by MeS or MeSe anions in DMF. (Alkylthio)phenyl and alkoxyphenyl alkyl selenides can be selectively dealkylated by nucleophilic aliphatic substitution with MeSNa or MeSeLi in DMF or by electron transfer with sodium in HMPA.In the first case the easiness with which the dealkylation occurs follows the order ArSeMe > ArOMe > ArSMe, whereas in the second case the order is ArSeR > ArSR > ArOR.The synthetic utility of these reactions is exemplified and discussed.
- Tiecco, Marcello,Testaferri, Lorenzo,Tingoli, Marco,Chianelli, Donatella,Montanucci, Manuela
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p. 4289 - 4296
(2007/10/02)
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- Sigmatropic Rearrangement of Ylides Derived from Benzylic Selenonium Salts
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The sigmatropic rearrangement of a series of ylides derived from benzylic selenonium salts has been observed.These ylides alkyl or aryl o-methylbenzyl selenides.The competition between nucleophilic displacement and ylide formation in the reaction of base with benzylic selenonium salts has been evaluated.
- Gassman, Paul G.,Miura, Takashi,Mossman, Allen
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p. 954 - 959
(2007/10/02)
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- Vinyl Selenides and Selenoxides: Preparation, Conversion to Lithium Reagents, Diels-Alder Reactivity, and Some Comparisons with Sulfur Analogues
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A variety of aryl vinyl selenides are prepared by reaction of vinyl Grignard reagents with aryl selenyl bromides or by reductive elimination of the adducts of lithiums with carbonyl compounds.Deprotonation of phenyl vinyl selenide is achieved with LDA at -78 deg C in THF.Vinyl selenides with β-alkyl groups require LiTMP and warmer temperatures (-50 deg C) for complete deprotonation.Allylic lithium reagents were obtained from 1-propenyl and 2-methyl-1-propenyl selenides whereas 1-butenyl or 3-methyl-1-butenyl selenides gave vinyl lithium reagents.Reaction with electrophiles proceeds in good to excellent yield.Primary halides require HMPA to react well.Unhindered carbonyl compounds react without enolization.Deprotonation with LDA is shown to be reversible, and during competitive deprotonation studies with LDA, aryl vinyl sulfides are found to be thermodynamically less acidic than aryl vinyl selenides (KS/Se=0.21 for phenyl vinyl and 0.3 for m-(trifluoromethyl)phenyl vinyl).Deprotonation with LiTMP is shown to be irreversible, and competitive deprotonation studies showed vinyl selenide to be kinetically more acidic as well S/Se=0.37 (phenyl vinyl),0.42 (m-(trifluoromethyl)phenyl vinyl)>.Most studies have shown sulfur compounds to be more acidic. m-(Trifluoromethyl)phenyl allyl sulfide as expected, is more acidic than selenium compound (kS/Se=3.8).Vinyl selenoxides can be prepared with m-chloroperbenzoic acid.They are not thermally stable enough to serve as acetylene equivalents in Diels-Alder reactions.Phenyl vinyl selenide gives a Diels-Alder addition product with 1,4-diphenylisobenzofuran but failed to give cycloaddition products with less reactive dienes.Phenyl vinyl selenoxide does not give a useful yield of lithium reagent upon reaction with amide bases.
- Reich, Hans J.,Willis, William W.,Clark, Peter D.
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p. 2775 - 2784
(2007/10/02)
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- Phenyl Selenide Anion, a Superior Reagent for the SN2 Cleavage of Esters and Lactones
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The scope and limitations of SN2-type cleavages of esters and lactones with phenyl selenide anion are discussed.The reagent, when generated properly, is found to be an extremely potent nucleophile.However, its nucleophilicity can be greatly attenuated by varying the counterion and/or the degree of solvation of the anion.The reagent can be used in the presence of a variety of functional groups and exhibits a high degree of selectivity; e.g., methyl esters are selectively cleaved in the presence of ethyl esters.As the hindrance around the carbinol carbon increases, products derived from acyl oxygen cleavage are observed.The mechanistic implications of this are discussed.
- Liotta, Dennis,Sunay, Ustun,Santiesteban, Hector,Markiewicz, William
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p. 2605 - 2610
(2007/10/02)
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- Substitution Reactions of Thallous Thiophenoxide and Thallous Phenylselenide with Halogen-Bearing Substrates
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Thallous thiophenoxide (1) and thallous selenide (2) were prepared by the action of either thallous ethoxide or thallous pentoxide on thiophenol and benzeneselenol.The reagents 1 and 2 reacted readily with aroyl and acyl halides, imidoyl chlorides, α-halo ketones, α-halo esters, α-halo lactones, α-halo carboxylic acids, allyl halides, alkyl halides, chlorotrimethylsilane, chloroacetonitrile, and N-chlorosuccinimide to give substitution products and varying amounts of diphenyl disulfide and diphenyl diselenide.The reactions were run as heterogeneous mixtures in ether.The origin of the diphenyl disulfide and diphenyl diselenide was homolytic cleavage of the thallium-sulfur or thallium-selenium bond, on the basis of the products derived from the reactions of N-chlorosuccinimide with 1 and 2.
- Detty, Michael R.,Wood, Gary P.
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- Base Treatment of Benzylic Selenonium Salts. Sigmatropic Rearrangements vs. Nucleophilic Displacement
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Treatment of certain benzylic selenonium salts with a variety of bases resulted in nucleophilic attack to yield either an alkylation or a benzylation of the base, while the use of sodium amide in liquid ammonia as base generated a selenonium ylide which gave ortho substitution of the benzyl group via sigmatropic rearrangement.
- Gassman, Paul G.,Miura, Takashi,Mossman, Allen
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p. 558 - 559
(2007/10/02)
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