Alkyl Aryl Sulfides Research Articles

Copper-Catalyzed Asymmetric Oxidation of Sulfides

Copper-catalyzed asymmetric sulfoxidation of aryl benzyl and aryl alkyl sulfides, using aqueous hydrogen peroxide as the oxidant, has been investigated. A relationship between the steric effects of the sulfide substituents and the enantioselectivity of the oxidation has been observed, with up to 93% ee for 2-naphthylmethyl phenyl sulfoxide, in modest yield in this instance (up to 30%). The influence of variation of solvent and ligand structure was examined, and the optimized conditions were then used to oxidize a number of aryl alkyl and aryl benzyl sulfides, producing sulfoxides in excellent yields in most cases (up to 92%), and good enantiopurities in certain cases (up to 84% ee).

Polyvinylpolypyrrolidone-Supported Boron Trifluoride (PVPP-BF3): Highly Efficient Catalyst for Chemoselective Oxygenation of Sulfides to Sulfones by H2O2

A highly efficient method for the oxidation of sulfides to sulfones using polyvinylpolypyrrolidone-supported boron trifluoride (PVPP-BF3) in the presence of (35%) hydrogen peroxide has been developed. This procedure cleanly oxidizes dialkyl and alkyl aryl sulfides to the corresponding sulfones in excellent yields at room temperature.

Efficient recyclable CuI-nanoparticle-catalyzed S-arylation of thiols with aryl halides on water under mild conditions

CuI nanoparticles efficiently catalyzed the C-S cross coupling of aryl and alkyl thiols with aryl halides in the absence of ligands on water under mild conditions. A wide range of diaryl sulfides and aryl alkyl sulfides are synthesized in good to excellent yields utilizing this protocol. This procedure is particularly noteworthy given its mild conditions, avoiding the undesired formation of disulfides through oxidation of thiols. The recovery and successful reutilization of the catalyst is described. Furthermore, the directed synthesis of bisarylated product is presented.

Synthesis of Aryl Alkyl Sulfides by γ-Addition of Aryl Thiols to Allenoates

Synthesis of Aryl Alkyl Sulfides by γ-Addition of Aryl Thiols to Allenoates

Palladium-catalyzed Carbon–Sulfur Cross-coupling Reactions of Aryl Chlorides with Indium Tris(organothiolates)

Abstract Pd-Catalyzed carbon–sulfur cross-coupling reactions of aryl chlorides with indium tris(organothiolates) were developed. Aryl chlorides reacted with indium tris(organothiolates) (0.35 equiv) in the presence of 4 mol % of Pd(OAc)2, 4.2 mol % of Xantphos, and Cs2CO3 as an additive, producing aryl–aryl and aryl–alkyl sulfides in good to excellent yields.

A recyclable fluorous thiourea organocatalyst for the chemoselective oxidation of sulfides

As a kind of organocatalyst, 1-[4-(perfluorooctyl)phenyl]-3-phenylthiourea was employed to the chemoselective oxidation of sulfides in the presence of 30% H 2O 2. A variety of diaryl, dialkyl, alkyl aryl sulfides could be oxidized to sulfoxide under the mild condition. The catalyst could be easily recovered by fluorous solid-phase extraction for reuse.

ChemInform Abstract: Nickel‐Catalyzed Alkenylative Cross‐Coupling Reaction of Alkyl Sulfides.

A novel cross-coupling reaction of alkyl aryl sulfides with aryl Grignard reagents has been achieved to produce the alkenyl-aryl coupling products in high yields by using catalytic Ni(cod)2 and a bulky N-heterocyclic carbene ligand, SIPr.

ChemInform Abstract: Planar Chiral Flavinium Salts — Prospective Catalysts for Enantioselective Sulfoxidation Reactions.

AbstractThe asymmetric H2O2 oxidation of aryl alkyl sulfides is smoothly catalyzed by an axially chiral flavinium salt to give enantioenriched sulfoxides in up to 54% optical purity.

Cross-Coupling Reactions Catalyzed by Iron Group Metals and <i>N</i>-Heterocyclic Carbenes via Nonconventional Reaction Mechanisms

New cross-coupling reactions catalyzed by iron or iron group metals (IGMs), consisting of Fe, Co, and Ni with N-heterocyclic carbenes (NHCs), are described in this report. Highly selective biaryl cross-coupling reactions between aryl halides and aryl Grignard reagents were achieved by using a combination of fluoride salts of IGMs and NHCs. In the course of the study, an unexpected alkenylative cross-coupling between alkyl aryl sulfides and aryl Grignard reagents was found, in which a typical Ni/NHC catalyst displayed unprecedented reactivity toward sulfide substrates. Theoretical studies suggest that the biaryl coupling and the alkenylative coupling reactions proceed via two nonconventional mechanisms, which are substantially different from the widely-accepted cross-coupling mechanism: In the biaryl cross-coupling, treatment of the catalyst mixtures of IGM fluorides and NHCs with an excess amount of the aryl Grignard reagent results in the generation of organometalate complexes, [Ar1MIIF2]MgBr (M=Fe, Co, and Ni). These organometalate species undergo oxidative addition of aryl halide substrates to form intermediates in a high oxidation state (most likely a+IV state) possessing two different aryl groups, Ar1Ar2MIVF2. The heteroleptic diaryl organometallic intermediates collapse easily to afford unsymmetrical biaryls in a highly selective manner. On the other hand, the alkenylative coupling reaction using a Ni/NHC catalyst involves formation of a low-oxidation-state Ni(0)-thioaldehyde complex, which is transformed to an alkenylnickel species via α-deprotonation of the thioaldehyde and subsequent C-S bond cleavage of the resulting enethiolate intermediate. The alkenylnickel species undergoes transmetalation with an aryl Grignard reagent to form alkenyl/aryl coupling products via reductive elimination. The present cross-coupling reactions catalyzed by IGMs with NHC ligands provide highly selective Csp2-Csp2 coupling methods for the synthesis of unsymmetrical biaryls and styrene derivatives, offering an opportunity to gain new mechanistic insights into IGM-catalyzed cross-coupling reactions.

M(C6H16N3)2(VO3)4 as heterogeneous catalysts. Study of three new hybrid vanadates of cobalt(ii), nickel(ii) and copper(ii) with 1-(2-aminoethyl)piperazonium

Three new hybrid vanadates have been synthesized under hydrothermal conditions with the formula M(C(6)H(16)N(3))(2)(VO(3))(4), where M = Co(II), Ni(II) and Cu(II). The structural analyses show that the phases are isostructural and crystallize in the monoclinic space group P2(1)/c. These compounds show a two-dimensional crystal structure, with sheets composed of [VO(3)](n)(n-) chains and metal centres octahedrally coordinated, chelated by two 1-(2-aminoethyl)piperazonium ligands. The thermal study reveals that the copper containing phase is less stable than the cobalt and nickel containing ones. The IR spectra of the three phases are very similar, with little differences in the inorganic bond region of the copper containing phase. The UV-visible spectra show that the cobalt(II) and the nickel(II) are in slightly distorted octahedral environments. The catalytic tests show that the phases act as heterogeneous catalysts for the selective oxidation of alkyl aryl sulfides, with both H(2)O(2) and tert-butylhydroperoxide as oxidizing agents. The influence of the steric hindrance in the kinetic profile has been studied. The catalytic reactions induce the partial amorphization of the phases.

Enantioselective carbon–sulfur bond formation: γ additions of aryl thiols to allenoates catalyzed by a chiral phosphepine

An effective phosphine-catalyzed method has been developed for the enantioselective addition of aryl thiols to the γ position of allenoates, thereby furnishing ready access to aryl alkyl sulfides in very good ee. An array of mechanistic data are consistent with addition of the chiral phosphine to the allenoate being the turnover-limiting step of the catalytic cycle. The optimized reaction conditions, as well as the mechanistic observations, differ markedly from an earlier report on asymmetric additions of alkyl thiols to allenoates, which highlights the potential for divergent behavior between alkyl and aryl thiols when serving as nucleophiles.

Nickel-Catalyzed Alkenylative Cross-Coupling Reaction of Alkyl Sulfides

A novel cross-coupling reaction of alkyl aryl sulfides with aryl Grignard reagents has been achieved to produce the alkenyl-aryl coupling products in high yields by using catalytic Ni(cod)(2) and a bulky N-heterocyclic carbene ligand, SIPr.

ChemInform Abstract: Effects of Substrate Structure on the Enantioselectivity and Stereochemical Course of Sulfoxidation Catalyzed by Cyclohexanone Monooxygenase.

Abstract A systematic study of the stereochemistry of oxidation at sulfur catalyzed by cyclohexanone monooxygenase from Acinetobacter using as the substrates numerous alkyl aryl sulfides, dialkyl sulfides and dialkyl disulfides has been earned out. It was found that the structure of the sulfide dramatically influenced the enantioselectivity of the enzyme which yielded sulfoxides with optical purities ranging from 99% ee and R-configuration to 93% ee and S-configuration.

ChemInform Abstract: Mechanism of Picolinic Acid Catalyzed Chromium(VI) Oxidation of Alkyl Aryl and Diphenyl Sulfides

ChemInform Abstract: Mechanism of Picolinic Acid Catalyzed Chromium(VI) Oxidation of Alkyl Aryl and Diphenyl Sulfides

ChemInform Abstract: A Facile Synthesis of Sulfoxides by Oxidation of Sulfides with Sodium Bromite in an Aprotic Solvent in the Presence of Clay Minerals.

The title oxidation has been performed in dichloromethane in the presence of “wet”-montmorillonite and -kaolin. The substrates studied include dialkyl, alkyl aryl, diaryl, and cyclic sulfides, which give the corresponding sulfoxides in good yields under neutral and mild conditions.

ChemInform Abstract: Asymmetric Oxidation of Sulfides by Cyclohexanone Monooxygenase.

Abstract Cyclohexanone monooxygenase catalyzes the asymmetric oxidazion of numerous alkyl aryl sulfides with the alkyl chain functionalyzed with Cl, CN, vinyl or hydroxy groups. Sulfoxides with enantiomeric excesses up to 99% were obtained. The structure of the sulfide markedly influenced enzyme enantioselectivity.

Photopromoted Ru-Catalyzed Asymmetric Aerobic Sulfide Oxidation and Epoxidation Using Water as a Proton Transfer Mediator

Ru(NO)-salen complexes were found to catalyze asymmetric aerobic oxygen atom transfer reactions such as sulfide oxidation and epoxidation in the presence of water under visible light irradiation at room temperature. Oxidation of sulfides including alkyl aryl sulfides and 2-substituted 1,3-dithianes using complex 2 as the catalyst proceeded with moderate to high enantioselectivity of up to 98% ee, and epoxidation of conjugated olefins using complex 3 as the catalyst proceeded with good to high enantioselectivity of 76-92% ee. Unlike biological oxygen atom transfer reactions that need a proton and electron transfer system, this aerobic oxygen atom transfer reaction requires neither such a system nor a sacrificial reductant. Although the mechanism of this oxidation has not been completely clarified, some experimental results support the notion that an aqua ligand coordinated with the ruthenium ion serves as a proton transfer agent for the oxygen activation process, and it is recycled and used as the proton transfer mediator during the process. Thus, we have achieved catalytic asymmetric oxygen atom transfer reaction using molecular oxygen that can be carried out under ambient conditions.

(PhCH2PPh3)+Br3 −: A Versatile Reagent for the Chemoselective Oxidation of Sulfides to Sulfoxides

Benzyltriphenylphosphonium tribromide (BTPTB), as a stable solid reagent, is easily prepared by the reaction of benzyltriphenylphosphonium bromide with Br2. This reagent can be used as an efficient reagent for the chemoselective oxidation of dialkyl and aryl-alkyl sulfides to their corresponding sulfoxides in the presence of diaryl sulfides and primary alcohols. All reactions were performed in a refluxing mixture of methanol and water in very short reaction times.

ChemInform Abstract: Carbon-Sulfur Bond-Forming Reductive Elimination Involving sp-, sp2-, and sp3-Hybridized Carbon. Mechanism, Steric Effects, and Electronic Effects on Sulfide Formation.

Palladium thiolato complexes [(L)Pd(R)(SR‘)], within which L is a chelating ligand such as DPPE, DPPP, DPPBz, DPPF, or TRANSPHOS, R is a methyl, alkenyl, aryl, or alkynyl ligand, and R‘ is an aryl or alkyl group, were synthesized by substitution or proton-transfer reactions. All of these thiolato complexes were found to undergo carbon−sulfur bond-forming reductive elimination in high yields to form dialkyl sulfides, diaryl sulfides, alkyl aryl sulfides, alkyl alkenyl sulfides, and alkyl alkynyl sulfides. Reductive eliminations forming alkenyl alkyl sulfides and aryl alkyl sulfides were the fastest. Eliminations of alkynyl alkyl sulfides were slower, and elimination of dialkyl sulfide was the slowest. Thus the relative rates for sulfide elimination as a function of the hybridization of the palladium-bound carbon follow the trend sp2 > sp ≫ sp3. Rates of reductive elimination were faster for cis-chelating phosphine ligands with larger bite angles. Kinetic studies, along with results from radical trapping re...

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.