Alkyl Aryl Sulfides Research Articles

HIO3 in the Presence of Wet SiO2: A Mild and Efficient Reagent for Selective Oxidation of Sulfides to Sulfoxides under Solvent‐Free Conditions

In the presence of wet SiO2, HIO3 is highly efficient for the selective oxidation of sulfides to sulfoxides. It may be applied to any type of dialkyl and alkyl aryl sulfides. It develops under solvent‐free conditions, and gives high yield in the presence of different functional groups on the sulfide at room temperature.

?-Arylsulfanyl-?-fluoro Carbenoids: Their Novel Chemistry and Synthetic Applications.

The bromine−magnesium exchange reactions of arylthiobromodifluoromethanes with Grignard reagents have been studied. Upon trapping with electrophiles, alkyl aryl sulfides and ketenedithioacetals are obtained. The reaction is proposed to occur via novel α-arylsulfanyl-α-fluoro carbenoids. The first examples of arylthiomethane multipole synthons are also reported.

Activation of Oxaziridines by Lewis Acids: Application in Enantioselective Sulfoxidation

The preparation of new and easily accessible chiral N-alkyloxaziridines for asymmetric sulfides oxidation was investigated. Most significantly, we report here that inert N-alkyloxaziridines can be activated by Lewis acids to achieve a fast, selective, and efficient oxygen atom transfer to sulfides. Asymmetric sulfoxidation by three new chiral oxaziridines (two of them were structurally characterized by X-ray analysis) afforded enantioselectivities ranging from 22% to 63% ee with the simplest aryl alkyl sulfides.

Enantioselective oxidation of sulfides with hydrogen peroxide catalyzed by vanadium complex of sterically hindered chiral Schiff bases

Sterically hindered chiral Schiff base ligands 4a– d were prepared from an aldehyde derived from BINOL. The vanadium complexes of the ligands catalyze an efficient, enantioselective H 2O 2-promoted sulfoxidation of alkyl aryl sulfides, and enantioselectivities as high as 98–99% ee are observed in the sulfoxidation of benzyl aryl sulfides.

α-Arylsulfanyl-α-fluoro Carbenoids: Their Novel Chemistry and Synthetic Applications

The bromine-magnesium exchange reactions of arylthiobromodifluoromethanes with Grignard reagents have been studied. Upon trapping with electrophiles, alkyl aryl sulfides and ketenedithioacetals are obtained. The reaction is proposed to occur via novel alpha-arylsulfanyl-alpha-fluoro carbenoids. The first examples of arylthiomethane multipole synthons are also reported. [reaction: see text]

A New Method for the Preparation of Alkyl Aryl Sulfides from Alcohols via Alkoxydiphenylphosphines by Oxidation–Reduction Condensation

Abstract A new method for the preparation of alkyl aryl sulfides from alcohols via alkoxydiphenylphosphines by oxidation–reduction condensation was established. Various primary, secondary, and tertiary alcohols were successfully converted into the corresponding sulfides in moderate to high yields.

Selective trifluorination of alkyl aryl sulfides using IF 5

In the reaction of IF 5 with alkyl aryl sulfides in heptane under reflux conditions, the arylthio group migrated once and three fluorine atoms were selectively introduced on the alkyl chain. In order to find the reason why the reaction stopped at the trifluorination step, we examined the oxidation potentials of the starting material, a reaction intermediate, and the product, and the time course of the reactions.

A Facile One‐Pot Synthesis of Alkyl Aryl Sulfides from Aryl Bromides.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Tris[(2‐oxazolinyl)phenolato]manganese(III) as Catalyst for Mild and Efficient Oxidation of Sulfides to Sulfones with Oxone®.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Multielectron atom transfer reactions of perchlorate and other substrates catalyzed by rhenium oxazoline and thiazoline complexes: reaction kinetics, mechanisms, and density functional theory calculations.

The title complexes, the Re(O)L(2)(Solv)(+) complexes (L = hoz, 2-(2'-hydroxyphenyl)-2-oxazoline(-) or thoz, 2-(2'-hydroxyphenyl)-2-thiazoline(-); Solv = H(2)O or CH(3)CN), are effective catalysts for the following fundamental oxo transfer reaction between closed shell molecules: XO + Y --> X + YO. Among suitable oxygen acceptors (Y's) are organic thioethers and phosphines, and among suitable oxo donors (XO's) are pyridine N-oxide (PyO), t-BuOOH, and inorganic oxyanions. One of the remarkable features of these catalysts is their high kinetic competency in effecting perchlorate reduction by pure atom transfer. Oxo transfer to rhenium(V) proceeds cleanly to afford the cationic dioxorhenium(VII) complex Re(O)(2)L(2)(+) in a two-step mechanism, rapid substrate (XO) coordination to give the precursor adduct cis-Re(V)(O)(OX)L(2)(+) followed by oxygen atom transfer (OAT) as the rate determining step. Electronic variations with PyO derivatives demonstrated that electron-withdrawing substituents accelerate the rate of Re(VII)(O)(2)L(2)(+) formation from the precursor adduct cis-Re(V)(O)(OX)L(2)(+). The activation parameters for OAT with picoline N-oxide and chlorate have been measured; the entropic barrier to oxo transfer is essentially zero. The potential energy surface for the reaction of Re(O)(hoz)(2)(OH(2))(+) with PyO was defined, and all pertinent intermediates and transition states along the reaction pathway were located by density functional theory (DFT) calculations (B3LYP/6-31G). In the second half of the catalytic cycle, Re(O)(2)L(2)(+) reacts with oxygen acceptors (Y's) in second-order reactions with associative transition states. The rate of OAT to substrates spans a remarkable range of 0.1-10(6) L mol(-)(1) s(-)(1), and the substrate reactivity order is Ph(3)P > dialkyl sulfides > alkyl aryl sulfides > Ph(2)S approximately DMSO, which demonstrates electrophilic oxo transfer. Competing deactivation and inhibitory pathways as well as their relevant kinetics are also reported.

Dinitrogen Tetroxide Impregnated Activated Charcoal (N2O4/Charcoal): Selective Oxidation of Sulfides to Sulfoxides and Disulfides to Thiosulfonates.

Dinitrogen tetroxide was easily impregnated on activated charcoal to give a stable heterogeneous reagent (N 2 O 4 /charcoal). The chemoselective oxidation of sulfides to sulfoxides in the presence of different sensitive functional groups was achieved using this reagent in CH 2 Cl 2 at room temperature. Dialkyl sulfides were also selectively converted to their corresponding sulfoxides in the presence of diaryl or alkyl-aryl sulfides. Oxidation of disulfides to thiosulfonates without any over oxidation was also performed at room temperature by this system.

A facile one-pot synthesis of alkyl aryl sulfides from aryl bromides.

A convenient one-pot synthetic method for the formation of alkyl aryl sulfides from various alkyl halides and lithium aryl thiolates that are prepared in situ by direct halogen-lithium exchange is reported. In particular, the method overcomes many of the problems encountered in previous reports; it is very quick, catalyst-free, and does not involve use of unstable aryl thiols.

Rotational Barriers, Charges, and Spin Densities in Alkyl Aryl Sulfide Radical Cations: A Density Functional Study

The structures and the torsional potentials for the rotation around the aryl−SR bond of a series of neutral alkyl aryl sulfides and their corresponding radical cations were studied by applying density functional theory at the B3LYP/6-311G** level. In all radical cations the most stable conformer corresponds to the structure in which the S-alkyl group is in the planar conformation, with sulfur and alkyl atoms coplanar with the aromatic ring. The rotational energy barriers were relatively high, ranging from 12.307 to 19.496 kcal/mol. In all cases substantial geometrical changes with respect to the parent sulfide were observed, the radical cation presenting a quinoidic structure, with quasi-single bonds alternating to quasi-double bonds, and a shorter CAr−S bond. These results illustrate the importance, in the radical cation, of the conjugation between the sulfur atom and the aromatic π system. Such a conjugation is not so important in the neutral molecules and in fact the energy minimum for alkyl phenyl sulfides is located in correspondence of the perpendicular form, with the exception of thioanisole for which the two effects seem to have a similar role. Calculation of Mulliken spin populations, MK and NPA charges showed that PhSR•+ and 4-NCC6H4SR•+ are mainly sulfur-centered radical cations, whereas 4-Me2NC6H4SMe•+ and 4-MeOC6H4SMe•+ are essentially aromatic radical cations with some charge and spin density at the sulfur atom. Ionization energies were also calculated for both the planar and perpendicular forms; for the PhSR series (particularly in the former case), they resulted in good agreement with the experimental ones.

Dioxygenase-catalysed sulfoxidation of bicyclic alkylaryl sulfides and chemoenzymatic synthesis of acyclic disulfoxides

Toluene- and naphthalene-dioxygenase-catalysed oxidation of six bicyclic disulfide substrates, using whole cells of Pseudomonas putida, gave the corresponding monosulfoxides with high ee values and enantiocomplementarity, in most cases. Two alcohol-sulfoxide diastereoisomers, formed from the reaction of the ( R)-1,3-benzodithiole-1-oxide metabolite with n-butyllithium and benzaldehyde, were separated and stereochemically assigned. Treatment, of enantiopure (1 R,3 R)-benzo-1,3-dithiole-1,3-dioxide, obtained by chemoenzymatic synthesis, with alkyllithium reagents, resulted in a novel ring-opening reaction which proceeded with inversion of configuration to yield a series of acyclic disulfoxides.

Dinitrogen Tetroxide Impregnated Activated Charcoal (N2O4/Charcoal): ­Selective Oxidation of Sulfides to Sulfoxides and Disulfides to Thiosulfonates

Dinitrogen tetroxide was easily impregnated on activated charcoal to give a stable heterogeneous reagent (N 2 O 4 /charcoal). The chemoselective oxidation of sulfides to sulfoxides in the presence of different sensitive functional groups was achieved using this reagent in CH 2 Cl 2 at room temperature. Dialkyl sulfides were also selectively converted to their corresponding sulfoxides in the presence of diaryl or alkyl-aryl sulfides. Oxidation of disulfides to thiosulfonates without any over oxidation was also performed at room temperature by this system.

Tris[(2-oxazolinyl)phenolato]manganese(III) as catalyst for mild and efficient oxidation of sulfides to sulfones with Oxone®

Tris[(2-oxazolinyl)phenolato]manganese(III), Mn(phox) 3 , catalysed oxidation of dialkyl, diaryl, dibenzyl, and alkyl aryl sulfides to the corresponding sulfones is carried out by Oxone® in biphasic conditions (CH 2 Cl 2 /H 2 O), in the presence of tetra n-butylammonium bromide as phase transfer agent at room temperature in very short reaction times (5 min.) with quantitative yields.

Iron-catalyzed asymmetric sulfide oxidation with aqueous hydrogen peroxide.

An iron in the fire: Iron-based catalysts promote the asymmetric oxidation of alkyl aryl sulfides to the corresponding sulfoxides with up to 90 % ee (see scheme). Simple hydrogen peroxide (30 % in water) serves as the terminal oxidant.

Polyfluorination of Aryl Alkyl Sulfides by IF5 with Concomitant Migration of the Arylthio Group.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Catalytic asymmetric sulfoxidation by chiral manganese complexes: acetylacetonate anions as chirality switches.

Three manganese(II) complexes, namely [Mn(1)(ClO(4))(2)] (3), [Mn(1)(acac)(2)] (4), and [Mn(2)(1)(acac)(4)] (5), were isolated from solutions of Mn(ClO(4))(2) or Mn(acac)(2), and an easily accessible diimine ligand (1S,2S)-N,N'-bis-pyridin-2-ylmethylene-cyclohexane-1,2-diamine (1). Their structure was determined by X-ray crystallography, and these complexes proved to be catalysts for asymmetric sulfide oxidation by H(2)O(2). Enantiomeric excesses ranging from 5% to 62% were obtained with a variety of aryl alkyl sulfides. We also observed an interesting "chirality switch" effect by the achiral acac anion reversing the enantioselectivity of the complex [Mn(1)(ClO(4))(2)] from the S to the R sulfoxide enantiomer.

Catalytic Asymmetric Oxidation of Alkyl Aryl Sulfides Mediated by a Series of Chiral N‐Alkyl‐1,2‐diphenylaminoethanol/Titanium/Water Complexes.

AbstractFor Abstract see ChemInform Abstract in Full Text.