Allylic Selenides Research Articles

ChemInform Abstract: Synthesis of Allyl Selenides by Palladium‐Catalyzed Decarboxylative Coupling.

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Palladium-Catalyzed Selenoacylation of Allenes Leading to the Regioselective Formation of Functionalized Allyl Selenides

Palladium-catalyzed regio- and stereoselective selenoacylation of allenes with selenol esters proceeded to produce functionalized allyl selenides with the acyl moiety at the inner carbon and the SePh group at the terminal carbon in high yields. A mechanism accounting for the observed regio- and stereoselectivities is proposed based on the results of DFT calculations.

Synthesis of allyl selenides by palladium-catalyzed decarboxylative coupling

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.

A PhSeCl-Mediated Allylic Oxidation of Prenyl Moiety: A Convenient Method for the Construction of 3-Isopenten-2-ol Unit

A phenylselenenyl chloride (PhSeCl)-mediated allylic oxidation to give allylically rearranged alcohol has been developed. A possible mechanism for the present reaction is generation of allylic selenide from prenyl moiety via [1,3]-sigmatropic rearrangement, followed by oxidation and [2,3]-sigmatropic rearrangement to afford 3-isopenten-2-ol.

Dechalcogenative allylic selenosulfide and disulfide rearrangements: complementary methods for the formation of allylic sulfides in the absence of electrophiles. Scope, limitations, and application to the functionalization of unprotected peptides in aqueous media.

Primary allylic selenosulfates (seleno Bunte salts) and selenocyanates transfer the allylic selenide moiety to thiols giving primary allylic selenosulfides, which undergo rearrangement in the presence of PPh3 with the loss of selenium to give allylically rearranged allyl alkyl sulfides. This rearrangement may be conducted with prenyl-type selenosulfides to give isoprenyl alkyl sulfides. Alkyl secondary and tertiary allylic disulfides, formed by sulfide transfer from allylic heteroaryl disulfides to thiols, undergo desulfurative allylic rearrangement on treatment with PPh3 in methanolic acetonitrile at room temperature. With nerolidyl alkyl disulfides this rearrangement provides an electrophile-free method for the introduction of the farnesyl chain onto thiols. Both rearrangements are compatible with the full range of functionality found in the proteinogenic amino acids, and it is demonstrated that the desulfurative rearrangement functions in aqueous media, enabling the derivatization of unprotected peptides. It is also demonstrated that the allylic disulfide rearrangement can be induced in the absence of phosphine at room temperature by treatment with piperidine, or simply by refluxing in methanol. Under these latter conditions the reaction is also applicable to allyl aryl disulfides, providing allylically rearranged allyl aryl sulfides in good yields.

Ni-catalyzed addition reaction of allylic selenides to alkynes

Nickel complex catalysts, Ni(cod) 2-2PPh 3 and Ni(cod) 2-dppb systems in particular, catalyze the addition reactions of phenyl allyl selenide to terminal alkynes to regioselectively afford 2-phenylseleno-1-allyl-1-alkenes in good to excellent yields. A mechanism that involves a η 3-allyl–nickel complex is proposed on the basis of isolation, crystal structure determination and reactivity study of the complex.

Solid-phase synthesis of ( Z)-allyl iodides from 3-acetoxy-2-methylene-alkanoates with recyclable polymer-supported selenium bromide

Reaction of polystyrene-supported lithium selenide with 3-acetoxy-2-methylene-alkanoates afforded the corresponding allyl selenide resins and subsequent cleavage from the polymer by treating with methyl iodide to furnish ( Z)-allyl iodides in good yields and high purities. The polymeric selenium reagent can be regenerated and reused. So it is a environmentally benign reagent.

A convenient and stereoselective synthesis of (Z)-allyl selenides via Sm/TMSCl system-promoted coupling of Baylis-Hillman adducts with diselenides

A simple and convenient procedure for stereoselective synthesis of (Z)-allyl selenides has been developed by a one-pot reaction of diselenides with Baylis-Hillman adducts in the presence of samarium metal-trimethylsilyl chloride under mild conditions. Presumably, the diselenides are cleaved by Sm/TMSCl system to form selenide anions, which then undergo S(N)2' substitution of Baylis-Hillman adducts to produce the (Z)-allyl selenides.

Vanadium‐Catalyzed Selenide Oxidation with in situ [2,3] Sigmatropic Rearrangement (SOS Reaction): Scope and Asymmetric Applications.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Vanadium-catalyzed selenide oxidation with in situ[2,3] sigmatropic rearrangement (SOS reaction): scope and asymmetric applications.

A vanadium-catalyzed method for the oxidation of prochiral aryl, allylic selenides with tandem [2,3] sigmatropic rearrangement has been developed. This protocol has been screened on a series of substrates to test for its generality and effectiveness. The applicability of this methodology to the synthesis of enantiomerically enriched allylic alcohols has been studied on a series of chiral oxazole-containing systems with a diastereomeric ratio (d.r.) of up to 85 : 15. The chiral transfer observed in the allyl alcohol products is the result of a net 1,9- and/or 1,10-induction. Finally, the first example of a selenium-oxygen nonbonding interaction in oxazole-containing selenide appears to have been observed via X-ray crystal analysis.

Diselenides and allyl selenides as glutathione peroxidase mimetics. Remarkable activity of cyclic seleninates produced in situ by the oxidation of allyl omega-hydroxyalkyl selenides.

A series of aliphatic diselenides and selenides containing coordinating substituents was tested for glutathione peroxidase (GPx)-like catalytic activity in a model system in which the reduction of tert-butyl hydroperoxide with benzyl thiol to afford dibenzyl disulfide and tert-butyl alcohol was performed under standard conditions and monitored by HPLC. Although the diselenides showed generally poor catalytic activity, allyl selenides proved more effective. In particular, allyl 3-hydroxypropyl selenide (25) rapidly generated 1,2-oxaselenolane Se-oxide (31) in situ by a series of oxidation and [2,3]sigmatropic rearrangement steps. The remarkably active cyclic seleninate 31 proved to be the true catalyst, reacting with the thiol via a postulated mechanism in which the thioseleninate 32 is first produced, followed by further thiolysis to selenenic acid 33 and oxidation-dehydration to regenerate 31. In contrast to catalysis with GPx, formation of the corresponding selenenyl sulfide 34 comprises a competing deactivation pathway in the catalytic cycle of 31, as a separate experiment revealed that authentic 34 was a much less effective catalyst than 31. 1,2-Oxaselenane Se-oxide (37), the six-membered homologue of 31, was formed similarly from allyl 4-hydroxybutyl selenide (26), but proved a less effective catalyst than 31. Compounds 31 and 37 are the first examples of unsubstituted monocyclic seleninate esters.

Stereoselective Synthesis of Substituted Allyl Selenide by the Reaction of (E)‐3‐Selanyl Vinylzirconocene Chloride with Aldehydes or Acyl Chlorides.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Preparation of Selanyl-Substituted Conjugated Enynes by Copper-Catalysed Coupling Reaction of (E)-γ-Selanyl Vinylzirconocene with Acetylenic Bromide

A stereoselective synthesis of conjugated enynes containing allyl selenide unit is reported. Selanyl-substituted conjugated enynes were obtained by the coupling reaction of ( E)-γ-selanyl vinylzirconocene with acetylenic bromide in the presence of CuCl.

DRD3/MSCI molecular genotypes and abnormal involuntary movements in first psychotic episode of patients followed-up one year

Nucleophilic substitution reactions of an allyl alcohol system in the 2′-deoxy-2′-methylidene pyrimidine nucleosides with various nucleophiles were investigated. The allyl alcohol system reacted with softer nucleophiles such as azide, thiophenoxide, and iodo anion through an SN2′ manner to afford 2′-substituted-methyl-2′,3′-didehydro-2′,3′-dideoxy nucleosides, but with hard oxygen-nucleophiles such as benzoyloxy and phenoxide through an SN2 manner to afford 2′-deoxy-2′-methylidene-3′-substituted nucleosides with inversion at the 3′-position. Based on this characteristic reactivity, 2′,3′-didehydro-2′,3′-dideoxy-2′-phenylselenomethyl pyrimidine nucleosides 16b and 16c were synthesized. These nucleosides were converted into 3′-amino-2′,3′-dideoxy-2′-methylidene pyrimidine nucleosides 3b and 3c via oxidative [2,3]-sigmatropic rearrangement of the allylic selenides as a key step. The cytosine derivative 3a was also prepared from the corresponding uracil derivative.

Stereoselective synthesis of Substituted Allyl Selenide by the reaction of (E)-3-Selanyl Vinylzirconocene Chloride with Aldehydes Or Acyl Chlorides

A regio- and stereoselective synthesis of substituted allyl selenides is described. Hydrozirconation of propargyl selenides and its further reaction with aldehydes or acyl chlorides afford 4-selanyl allyl alcohols or 4-selanyl-2-en-1-one, respectively.

A New Approach to Isolevoglucosenone via the 2,3‐Sigmatropic Rearrangement of an Allylic Selenide.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A NEW APPROACH TO ISOLEVOGLUCOSENONE VIA THE 2,3-SIGMATROPIC REARRANGEMENT OF AN ALLYLIC SELENIDE

A convenient method is described for the synthesis of isolevoglucosenone 5, via allylic selenide 3, and its rearrangement to allylic alcohol 4, followed by oxidation with manganese oxide. Isolevoglucosenone 5, is produced in 62% overall yield.

Synthesis of 2-alkyl (and aryl)-1-aryl-2-propen-1-ones via m-CPBA mediated oxidation of γ-(benzotriazol-1-yl)allylic selenides

Treatment of 2-alkyl (and aryl)-3-aryl-3-(benzotriazol-1-yl)allylic selenides with m-CPBA (1 equiv.) for 10 min in CH 2Cl 2 at rt gave 2-alkyl (and aryl)-1-aryl-2-propen-1-ones in excellent yields.

Facile Formation of Ytterbium Diiodide and Its Use in the Synthesis of Allyl Selenides

AbstractYtterbium metal reacts with iodine to generate ytterbium diiodide directly, which can react with diselenides to form ytterbium selenolates (RSeYbI2). These species reacted smoothly with allyl bromide to give allyselenides in moderate to good yields under neutral conditions.

Synthesis of Allyl Selenides Promoted by an Sm/ZnCl2 Bimetal System in the Presence of Water

AbstractThe reaction of diselenides with allylic bromides proceeded smoothly in an Sm/ZnCl2 bimetal system in THF‐H2O to afford allyl selenides in good yield.