Alkyl Phenyl Sulfides Research Articles

Sulphide as a leaving group: highly stereoselective bromination of alkyl phenyl sulphides.

A conceptionally novel nucleophilic substitution approach to synthetically important alkyl bromides is presented. Using molecular bromine (Br2), readily available secondary benzyl and tertiary alkyl phenyl sulphides are converted into the corresponding bromides under exceptionally mild, acid- and base-free reaction conditions. This simple transformation allows the isolation of elimination sensitive benzylic β-bromo carbonyl and nitrile compounds in mostly high yields and purities. Remarkably, protic functionalities such as acids and alcohols are tolerated. Enantioenriched benzylic β-sulphido esters, readily prepared by asymmetric sulpha-Michael addition, produce the corresponding inverted bromides with high stereoselectivities, approaching complete enantiospecificity at -40 °C. Significantly, the reported benzylic β-bromo esters can be stored without racemisation for prolonged periods at -20 °C. Their synthetic potential was demonstrated by the one-pot preparation of γ-azido alcohol (S)-5 in 90% ee. NMR studies revealed an initial formation of a sulphide bromine adduct, which in turn is in equilibrium with a postulated dibromosulphurane intermediate that undergoes C-Br bond formation.

OXIDATION OF ORGANIC SULFIDES BY QUINOLINIUM CHLOROCHROMATE: A KINETIC AND MECHANISTIC APPROACH

The oxidation of organic sulfides by quinolinium chlorochromate (QCC) resulted in the formation of the corresponding sulfoxides. The reaction is first order with respect to QCC. A Michaelis-Menten type kinetics was observed with respect to the reactants. The reaction is catalyzed by toluene-p-sulfonic acid (TsOH). The oxidation was studied in nineteen different organic solvents. An analysis of the solvent effect by Swain's equation showed that the both cation‑ and anion‑solvating powers of the solvents play important roles. The correlation analyses of the rate of oxidation of thirty four sulfides were performed in terms of various single and multiparametric equations. For the aryl methyl sulfides, the best correlation is obtained with Charton's LDR and LDRS equations. The oxidation of alkyl phenyl sulfides exhibited a very good correlation in terms of Pavelich-Taft equation. The polar reaction constants are negative indicating an electron‑deficient sulfur centre in the rate‑determining step. A mechanism involving formation of a sulphenium cation intermediate in the slow step has been proposed.

Desulfurative Chlorination of Alkyl Phenyl Sulfides.

The chlorination of readily available secondary and tertiary alkyl phenyl sulfides using (dichloroiodo)benzene (PhICl2) is reported. This mild and rapid nucleophilic chlorination is extended to sulfa-Michael derived sulfides, affording elimination-sensitive β-chloro carbonyl and nitro compounds in good yields. The chlorination of enantioenriched benzylic sulfides to the corresponding inverted chlorides proceeds with high stereospecificity, thus providing a formal entry into enantioenriched chloro-Michael adducts. A mechanism implying the formation of a dichloro-λ4-sulfurane intermediate is proposed.

Kinetics and Correlation Analysis of Reactivity in the Oxidation of Some Alkyl Phenyl Sulfides by Benzimidazolium Dichromate

Abstract The oxidation of some alkyl phenyl sulfides by benzimidazolium dichromate (BIDC) in dimethyl sulfoxide, to the corresponding sulfoxides, is first order with respect to BIDC. Michaelis–Menten type kinetics was observed with respect to sulfide. Thermodynamic parameters for the complex formation and activation parameters for the decomposition of the complex were calculated. The reaction is proton-catalyzed and the order is less than one. It appears that the BIDCH+ is the active electrophile. An intermediate of composition sulfide–BIDC–H+ has been envisaged. The high value of negative entropy of activation suggests a cyclic transition state in the rate-determining step. The reaction exhibited negative polar reaction constants and a small degree of steric hindrance. The rate of oxidation of sulfide was determined in 19 organic solvents. An analysis of the solvent effect by Swain’s equation indicated that though both the anion and cation solvating powers of the solvent contribute to the observed solvent effect, the role of cation solvation is major. A mechanism involving the rate-determining oxygen atom transfer in complex, formed by a nucleophilic attack of sulfide-sulfur on BIDCH+ in a rapid pre-equilibrium, is suggested to give corresponding sulfoxide via. a cyclic transition state.

Titanium–salan‐catalyzed asymmetric sulfoxidations with H2O2: design of more versatile catalysts

Titanium–salan complexes with 3,3’‐diphenyl substituents in the salicylidene rings of the salan ligand are efficient sulfoxidation catalysts, capable of catalyzing the asymmetric oxidation of bulky aryl benzyl sulfides with H2O2 with good to high enantioselectivities. In this paper, substituent effects on titanium‐salan‐catalyzed enantioselective oxidation of sulfides to sulfoxides have been systematically investigated. Titanium–salan catalysts with halogen substituents at the 5,5’‐positions (3,3’‐H2dihydrogen substituted) have been found to catalyze the oxidation of both bulky aryl benzyl sulfides and small alkyl phenyl sulfides with good to high enantioselectivities. Kinetic data witness a direct attack of the sulfide to the electrophilic active oxygen species; a consistent reaction mechanism is proposed. Copyright © 2013 John Wiley & Sons, Ltd.

Cationic arene ruthenium(ii) complexes with chelating P-functionalized alkyl phenyl sulfide and sulfoxide ligands as potent anticancer agents

The synthesis and characterization of cationic ruthenium(II) complexes of the type [Ru(η(6)-p-cym)Cl{Ph(2)P(CH(2))(n)S(O)(x)Ph-κP,κS}][PF(6)] (n = 1-3; x = 0, 1; p-cym = p-cymene) are presented. Furthermore, their high biological potential even against cisplatin-resistant tumor cell lines and their structure-activity relationships are discussed.

Gas-phase S-alkylation of benzenethiol with aliphatic alcohols, ethers, esters, alkyl halides and olefins over halide cluster catalysts of Groups 5 and 6 transition metals

Benzenethiol was reacted with methanol under a hydrogen stream over [(Nb6Cl12)Cl2(H2O)4]·6H2O supported on silica gel. Catalytic activity of the cluster commenced above 250°C, yielding methyl phenyl sulfide. The selectivity was 98% at 400°C. Molybdenum, tantalum and tungsten halide clusters with the same octahedral metal framework also catalyzed the reaction. Primary alcohols with shorter alkyl chains were effective reagents for the S-alkylation. Aliphatic ethers, dialkyl carbonates, orthoesters and alkyl halides were effective reagents for the S-alkylation. When 1-hexene was applied to the reaction, spontaneous and catalytic S-alkylation proceeded simultaneously above 200°C, yielding n-hexyl phenyl sulfide. When alkyl acetates were subjected to this reaction, the niobium cluster afforded S-phenyl thioacetate, and the other clusters afforded alkyl phenyl sulfides selectively. A Brønsted acid site attributable to a hydroxo ligand, which is formed on the cluster complex by thermal activation, is proposed as the active site of the catalysts.

Oxidation of Some Organic Sulfides by Benzyltrimethylammonium Chlorobromate: A Kinetic and Mechanistic Approach

The oxidation of 34 sulfides by benzyltrimethylammonium chlorobromate (BTMACB) resulted in formation of the corresponding sulfoxides. The reaction is first order with respect to both BTMACB and the sulfide. The solvent composition effect indicated that the rate of reaction increases with increase in the polarity of the medium. The reaction failed to induce the polymerization of acrylonitrile. There is no effect of added benzyltrimethylammonium chloride or potassium bromide. Chlorobromate ion is postulated as the reactive oxidizing species. The rates of oxidation of meta- and para-substituted phenyl methyl sulfides were correlated with Charton's LDR equation. The rates of oxidation of the ortho-compounds showed excellent correlation with the LDRS equation. The oxidation of meta-compounds exhibited a greater dependence on the field effect. The reaction is subject to steric inhibition when an ortho-substituent is present. The oxidation of alkyl phenyl sulfides is subject to both polar and steric effects of the alkyl groups. The polar reaction constants are negative, indicating an electron-deficient sulfur centre in the rate-determining step. A mechanism has been proposed involving formation of a halogenosulfonium cation in the slow step.

Rhodium(I) complexes with κ P coordinated ω-phosphinofunctionalized alkyl phenyl sulfide, sulfoxide and sulfone ligands and their reactions with sodium bis(trimethylsilyl)amide and Ag[BF 4

Reactions of ω-diphenylphosphinofunctionalized alkyl phenyl sulfides Ph 2P(CH 2) n SPh ( n = 1, 1a; 2, 2a; 3, 3a), sulfoxides Ph 2P(CH 2) n S(O)Ph ( n = 1, 1b; 2, 2b; 3, 3b) and sulfones Ph 2P(CH 2) n S(O) 2Ph ( n = 1, 1c; 2, 2c; 3, 3c) with dinuclear chlorido bridged rhodium(I) complexes [(RhL 2) 2(μ-Cl) 2] (L 2 = cycloocta-1.5-diene, cod, 4; bis(diphenylphosphino)ethane, dppe, 5) afforded mononuclear Rh(I) complexes of the type [RhCl{Ph 2P(CH 2) n S(O) x Ph-κ P}(cod)] 1 1 Here and in the following the letters a, b, and c in the numbering schemes refer to a sulfanyl ( x = 0), sulfinyl ( x = 1) and sulfonyl ( x = 2) functionality, respectively. ( n/ x = 1/0, 6a; 1/1, 6b; 1/2, 6c; 2/0, 8a; 2/1, 8b; 2/2, 8c; 3/0, 10a; 3/1, 10b; 3/2, 10c) and [RhCl{Ph 2P(CH 2) n S(O) x Ph-κ P}(dppe)] ( n/ x = 1/0, 7a; 1/1, 7b; 1/2, 7c; 2/0, 9a; 2/1, 9b; 2/2, 9c; 3/0, 11a; 3/1, 11b; 3/2, 11c) having the P^S(O) x ligands κ P coordinated. Addition of Ag[BF 4] to complexes 6– 11 in CH 2Cl 2 led with precipitation of AgCl to cationic rhodium complexes of the type [Rh{Ph 2P(CH 2) n S(O) x Ph-κ P,κ S/ O}L 2][BF 4] having bound the P^S(O) x ligands bidentately in a κ P,κ S ( 13a– 18a, 15b– 18b) or a κ P,κ O ( 13b, 14b, 13c– 18c) coordination mode. Unexpectedly, the addition of Ag[BF 4] to 6a in THF afforded the trinuclear cationic rhodium(I) complex [Rh 3(μ-Cl)(μ-Ph 2PCH 2SPh-κ P:κ S) 4][BF 4] 2·4THF ( 12·4THF) with a four-membered Rh 3Cl ring as basic framework. Addition of sodium bis(trimethylsilyl)amide to complexes 6– 11 led to a selective deprotonation of the carbon atom neighbored to the S(O) x group (α-C) yielding three different types of organorhodium complexes: a) Organorhodium intramolecular coordination compounds of the type [Rh{CH{S(O) x Ph}CH 2CH 2PPh 2-κ C,κ P}L 2] ( 22a– c, 23a– c), b) zwitterionic complexes [Rh{Ph 2PCHS(O) x Ph-κ P,κ S/ O}L 2] having κ P,κ S ( 21a, 21b) and κ P,κ O ( 20b/ c, 21c) coordinated anionic [Ph 2PCHS(O) x Ph] ligands, and c) the dinuclear rhodium(I) complex [{Rh{μ-CH(SPh)PPh 2-κ C:κ P}(cod)} 2] ( 19). All complexes were fully characterized spectroscopically and complexes 15b, 15c, 12·4THF and 19·THF additionally by X-ray diffraction analysis. DFT calculations of zwitterionic complexes gave insight into the coordination mode of the [Ph 2PCHS(O)Ph] ligand (κ P,κ S versus κ P,κ O).

ChemInform Abstract: Novel Generation of Phenylsulfenium Ion and Aromatic Phenylthiolation. Reactions of Hydrazoic Acid, Alkyl Azides, and Hydroxylamine Derivatives with Alkyl Phenyl Sulfides in the Presence of Both Trifluoromethanesulfonic Acid and Trifl

ChemInform Abstract: Novel Generation of Phenylsulfenium Ion and Aromatic Phenylthiolation. Reactions of Hydrazoic Acid, Alkyl Azides, and Hydroxylamine Derivatives with Alkyl Phenyl Sulfides in the Presence of Both Trifluoromethanesulfonic Acid and Trifl

ChemInform Abstract: Mn-Salen Catalyzed Nitrene Transfer Reaction: Enantioselective Imidation of Alkyl Aryl Sulfides.

Abstract Enantioselective imidation of alkyl aryl sulfides was achieved by using (R,R)- or (R,S)-Mn-salen complex [(R,R)-3 or (R,S)-3] as a catalyst. The optimum reaction conditions are dependent upon the substrates examined. For example, the imidation of alkyl phenyl sulfides with PhI=NTs using Mn-salen complex (R,R)-3 as a catalyst in the presence of N-methylmorpholine N-oxide showed high enantioselectivity (up to 89% ee). On the other hand, the reaction of methyl 2,4-dinitrophenyl sulfide was effected (97% ee) by using Mn-salen complex (R,S)-3 as the catalyst in the absence of N-methylmorpholineN-oxide.

Kinetics and correlation analysis of reactivity in the oxidation of organic sulfides by butyltriphenylphosphonium dichromate

The oxidation of a number of monosubstituted aryl methyl, alkyl phenyl, dialkyl, and diphenyl sulfides by butyltriphenylphosphonium dichromate (BTPPD), to the corresponding sulfoxides, is first order with respect to BTPPD and is second order with respect to sulfide. The reaction is catalysed by hydrogen ions and the dependence is of second order. The oxidation of meta- and para-substituted aryl methyl sulfides correlated best in terms of Hammett equation, the reactions exhibited negative polar reaction constant. The ortho-substituted compounds correlated best in terms of Charton’s triparametric equation with negative polar constant and a small degree of steric hindrance. The oxidation of alkyl phenyl sulfides exhibited a good correlation in terms of Pavelich-Taft equation confirming that the electron-donating power of the alkyl group increases the rate, however, the reactivity is not markedly controlled by the bulkiness of the alkyl group. The rates of oxidation of sulfides were determined in nineteen organic solvents. An analysis of the solvent effect by multi-parametric equations indicated the relatively greater importance of the cation-solvating power of the solvents. A mechanism involving a single-step electrophilic oxygen transfer from BTPPD to the sulfide leading to polar transition state has been proposed.

Indium-mediated cleavage of diphenyl diselenide and diphenyl disulfide: efficient one-pot synthesis of unsymmetrical diorganyl selenides, sulfides, and selenoesters

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.

Kinetics and mechanism of the oxidation of some organic sulfides by morpholinium chlorochromate

AbstractThe oxidation of organic sulfides by morpholinium chlorochromate (MCC) resulted in the formation of the corresponding sulfoxides. The reaction is first order with respect to both MCC and the sulfide. The reaction is catalyzed by toluene‐p‐sulfonic acid (TsOH). The oxidation was studied in 19 different organic solvents. An analysis of the solvent effect by Swain's equation showed that both the cation‐ and anion‐solvating powers of the solvents play important roles. The correlation analyses of the rate of oxidation of 34 sulfides were performed in terms of various single and multiparametric equations. For the aryl methyl sulfides, the best correlation is obtained with Charton's localized‐delocalized‐resonance and localized‐delocalized‐resonance‐steric equations. The oxidation of alkyl phenyl sulfides exhibited a very good correlation in terms of the Pavelich–Taft equation. The polar reaction constants are negative, indicating an electron‐deficient sulfur center in the rate‐determining step. A mechanism involving formation of a sulfonium cation intermediate in the slow step has been proposed. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 41: 65–72, 2009

Kinetics and mechanism of (salen)MnIII–catalysed hydrogen peroxide oxidation of alkyl aryl sulphides

AbstractThe kinetics of (salen)MnIII complexes catalysed oxidation of aryl methyl and alkyl phenyl sulphides with hydrogen peroxide have been investigated at 25°C in 80% acetonitrile – 20% water spectrophotometrically. The reaction follows first‐order kinetics in (salen)MnIII complex and zero‐order kinetics in hydrogen peroxide. The order of the reaction with respect to sulphide is fractional and saturation in reaction rate occurs at higher sulphide concentrations. The pseudo first‐order rate constants have been analysed as per Michaelis–Menten kinetics to obtain the values of k2, the oxidant‐substrate complex decomposition rate constant, and K, the oxidant‐substrate complex formation constant. The effects of nitrogenous bases, free radical inhibitor and changes in solvent composition have also been studied. A suitable mechanism, supported by electronic‐oxidant and electronic‐substrate effect studies, involving a manganese(III)‐hydroperoxide complex as reactive species has been proposed. Copyright © 2007 John Wiley & Sons, Ltd.

Rates of C−S Bond Cleavage in tert-Alkyl Phenyl Sulfide Radical Cations

[reaction: see text] Radical cations of tert-alkyl phenyl sulfides 1-4 have been generated photochemically in MeCN in the presence of the N-methoxyphenanthridinium cation (MeOP(+)), and the rates of C-S bond cleavage have been determined by laser flash photolysis.

Convenient and Efficient Synthesis of 1,1‐Bis‐(4‐alkylthiophenyl)‐1‐alkenes via Tandem Friedel—Crafts Acylation and Alkylation of Sulfides and Acyl Chlorides.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Kinetics and Mechanism of the Oxidation of Organic Sulfides by [Bis(trifluoroacetoxy)iodo]benzene

The oxidation of organic sulfides by [bis(trifluoroacetoxy)iodo]benzene (TFAIB), to the corresponding sulfoxides, is first order with respect to TFAIB, hydrogen-ions, and the sulfide. The correlation analyses of the rate of the oxidation of thirty-five sulfides were performed in terms of various single and multiparametric equations. For the aryl methyl sulfides, the best correlation is obtained with Charton's LDR and LDRS equations. The oxidation of alkyl phenyl sulfides exhibited a very good correlation in terms of the Pavelich-Taft equation. The polar regression coefficients are negative. A mechanism involving formation of a sulfonium-cation intermediate in the slow step has been proposed.

CeCl3/Sm Induced Reductive Cleavage of the S—S Bond in Disulfide: A Novel Method for the Synthesis of β‐Thioesters, Thiol‐esters and Alkylphenyl Sulfides.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Convenient and Efficient Synthesis of 1,1‐Bis‐(4‐alkylthiophenyl)‐1‐alkenes via Tandem Friedel–Crafts Acylation and Alkylation of Sulfides and Acyl Chlorides

1,1‐Bis(4‐alkylthiophenyl)‐1‐alkenes were conveniently and efficiently prepared from alkyl phenyl sulfides and acyl chlorides via a tandem Friedel–Crafts acylation and alkylation in the presence of anhydrous aluminum chloride. The scope, limitation, and mechanism of the tandem reaction were also discussed.