Benzyl Phenyl Sulfide Research Articles

Structural and Mechanistic Studies on Substrate and Stereoselectivity of the Indole Monooxygenase VpIndA1: New Avenues for Biocatalytic Epoxidations and Sulfoxidations.

Flavoprotein monooxygenases are a versatile group of enzymes for biocatalytic transformations. Among these, group E monooxygenases (GEMs) catalyze enantioselective epoxidation and sulfoxidation reactions. Here, we describe the crystal structure of an indole monooxygenase from the bacterium Variovorax paradoxus EPS, a GEM designated as VpIndA1. Complex structures with substrates reveal productive binding modes that, in conjunction with force-field calculations and rapid mixing kinetics, reveal the structural basis of substrate and stereoselectivity. Structure-based redesign of the substrate cavity yielded variants with new substrate selectivity (for sulfoxidation of benzyl phenyl sulfide) or with greatly enhanced stereoselectivity (from 35.1 % to 99.8 % ee for production of (1S,2R)-indene oxide). This first determination of the substrate binding mode of GEMs combined with structure-function relationships opens the door for structure-based design of these powerful biocatalysts.

Oxidations of aromatic sulfides promoted by the phthalimide N-oxyl radical (PINO)

The oxidation of a series of alkyl aryl sulfides promoted by the phthalimide N-oxyl radical (PINO) has been investigated by kinetic and product analysis. Sulfoxides are formed as major reaction products in the oxidation of thioanisoles and benzyl phenyl sulfides. The observation of fragmentation products in the oxidation of 2-phenyl-2-propyl phenyl sulfide and diphenylmethyl phenyl sulfide indicates that the reaction involves an initial electron transfer reaction from the sulfide to PINO with the formation of aryl sulfide radical cations and the anion PINO-. Combination of the species then leads to a radical adduct precursor of sulfoxides while the rapid C–S cleavage occurs with aryl sulfide radical cations that can form the stable 2-phenyl-2-propyl or diphenylmethyl carbocation.

A Green Route to Benzyl Phenyl Sulfide from Thioanisole and Benzyl Alcohol over Dual Functional Ionic Liquids.

Benzyl phenyl sulfide is a kind of important chemicals with wide usage, which is mainly prepared through a nucleophilic reaction of thiophenol with benzyl chlorides or benzyl alcohols, suffering from inherent drawbacks, such as low efficiency, requirements for equivalent acid or base catalysts and formation of harmful byproducts and waste. Herein, we report a green route to access various benzyl phenyl sulfide derivatives in good to excellent yields under mild conditions via the reaction of thioanisoles with benzyl alcohols over ionic liquid 1-propylsulfonate-3-methylimidazolium trifluoromethanesulfonate ([SO3 HPrMIm][OTf]). Mechanism investigation indicates that the synergic effect of cation and anion of [SO3 HPrMIm][OTf] activates thioanisoles and benzyl alcohols via hydrogen bonding, thus catalyzes the dehydration of benzyl alcohol to dibenzyl ether and the subsequent metathesis reaction between dibenzyl ether and benzyl phenyl sulfide, finally generating benzyl phenyl sulfide derivatives. This is a simple, highly efficient, and green approach to produce benzyl phenyl sulfide derivatives, which has promising application potentials.

Pd(II)−Catalyzed Non‐Directed Benzylic C(sp3)−H Activation: Cascade C(sp3)−S Bond Cleavage to Access Benzaldehydes from Benzylphenyl Sulfides and Sulfoxides

AbstractA novel, efficient and mutual strategy on Pd(II)−catalyzed inert benzylic C(sp3)−H bond activation of benzylphenyl sulfides and sulfoxides has been developed that provides access to a series of benzaldehydes via cascade C(sp3)−S bond cleavage in one pot. The highlight of this protocol is the regiospecific activation of less reactive benzylic C(sp3)−H bond as compared to heteroatom‐directed more reactive C(sp2)−H bond, thus providing a strategy for late−stage site−selective C(sp3)−H bond functionalization. The reaction proceeds under air in moderate to good yields with excellent functional groups tolerance.

Copper-Catalyzed C–S Formation for the Synthesis of Benzyl Phenyl Sulfides from Dithiocarbamates

AbstractAn odorless and efficient protocol for the synthesis of benzyl phenyl sulfides is reported. Starting from environmentally friendly phenyl dithiocarbamates and commercially available benzyl halides as starting materials, the target compounds (benzyl phenyl sulfides) could be obtained smoothly and easily by using copper salt as catalyst and Cs2CO3 as base. This method features ligand/additive-free, the use of readily available starting materials, inexpensive catalysts, and good substrate suitability, illustrating its potentially synthetic value for the convenient preparation of some biologically active molecules.

Methods, Syntheses and Characterization of Diaryl, Aryl Benzyl, and Dibenzyl Sulfides

Twenty-four aryl benzyl sulfides, diaryl sulfides and dibenzyl sulfides were synthesized by four methods and characterized by 1H NMR, FT-IR and Gas chromatography. The reaction conditions of different synthesis methods were studied from the aspects of time, solvent, base and dispersant. The molecular structures of benzylphenyl sulfide (2S), (4-tert-butylbenzyl)(4-methylphenyl) sulfide (4S), (4-methylbenzyl)(4-methylphenyl) sulfide (9S), di(4-methylphenyl) sulfide (11S), (3,5-dimethylphenyl)(4-methyl phenyl) sulfide (15S), and dibenzyl sulfide (19S) [22] have been determined by single-crystal X-ray crystallography. Compounds 2S and 15S crystallize in the monoclinic space group P21/c, with a = 12.278(3), b = 15.894(3), c = 5.6056(11) A, β = 94.532(2)°, and Z = 4 for 2S, and a = 9.800(9), b = 7.950(7), c = 16.690(15) A, β = 100.890(12)°, and Z = 4 for 15S. The unit cell of 4S has a triclinic Pī symmetry with the cell parameters a = 6.0436(10), b = 8.7871(14), c = 15.535(2) A, α = 81.921(2)°, β = 81.977(2)°, γ = 80.889(2)°, and Z = 2. Compounds 9S and 11S both crystallize in the orthorhombic space group P212121, with a = 6.188(3), b = 8.041(4), c = 26.005(14) A, and Z = 4 for 9S, and a = 5.835(2), b = 8.010(3), c = 25.131(9) A, and Z = 4 for 11S. Twenty-four aryl sulfide compounds with different substituents were synthesized and characterized, and the molecular structures of six different sulfide compounds have been determined by single-crystal X-ray crystallography.

Selective Catalytic Oxidation of Organic Sulfides to Sulfoxides without Forming Sulfones over Solid Molybdenum Blue: Kinetic and Thermodynamic Studies

The present investigation reports studies on the selective catalytic oxidation of organic sulfide substrates over molybdenum blue catalyst supported on boron phosphate. The catalyst was synthesized through partial precipitation method and characterized by XRD, FTIR and SEM techniques. The sulfoxidation was carried out in a batch reactor using benzyl phenyl sulfide as the substrate over the present catalyst and the reaction parameters were varied and optimized. The results were compared with the MoO3 impregnated boron phosphate. The catalyst was also studied for its performance over other sulfide substrates and the results were compared with available studies in literature. The reaction followed pseudo first-order kinetics and rate of the reaction under optimized condition was 10.1 × 10-3 min-1, with energy of activation of 29.3 kJ/mol. The Mo-O-Mo bridging and -Mo=O bonds present in molybdenum blue were participating in the reaction and possible mechanism has been proposed. The 100% selectivity of the product towards sulfoxide has been attributed to the big-wheel structure of molybdenum blue as it sterically hinders further reaction of sulfoxides formed to sulfones.

Novel benzyl phenyl sulfide derivatives as antibacterial agents against methicillin-resistant Staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus (MRSA) infection is a major threat to human health due to its resistance to almost all classes of antibiotics. Discovery of novel antibacterial agents with new structures which combat the pathogens responsible for MRSA is urgent. In this study, three series of benzyl phenyl sulfide derivatives were designed and synthesized, and their antibacterial activity against eleven MRSA strains were evaluated. The results showed that two series of the synthetic compounds (5a-5l and 12p-12u) exhibit potent antibacterial activity against S. aureus and MRSA, with minimum inhibitory concentrations of 2-64 μg/mL. The structure-activity relationships are discussed and the mechanism of the antibacterial activity was shown to involve the destruction of the bacterial cell membrane. Finally, the MTT assay results suggest that the toxicity of compounds 5f and 5h is selective between bacteria and mammalian cells.

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.

Green, inexpensive, and fast conversion of sulfides to sulfoxides by multiusable Mo(VI) macrocyclic Schiff base complex supported on Fe3O4 nanoparticles in solvent-free conditions

In the present study, the macrocyclic-based Mo(VI) Schiff base complex was harbored on Fe 3 O 4 nanoparticles and characterized by X-ray powder diffraction, scanning electron microscope, energy-dispersive X-ray spectroscopy, infrared spectroscopy, transmission electron microscopy, vibrating sample magnetometry, diffuse reflectance spectra, and atomic absorption spectroscopy. Separable nanocatalyst was tested under solvent-free conditions for the oxidation of methyl phenyl sulfide, diphenyl sulfide, benzyl phenyl sulfide, dipropyl sulfide, dibutyl sulfide, dimethyl sulfide, bis (4-hydroxyphenyl) sulfide, diallyl sulfide, and benzothiophene using H 2 O 2 (30% in water) as green oxidant. This catalyst is very efficient for thioanisole oxidation with 100% conversion in 3 min. We were able to separate the nanocatalyst magnetically using external magnetic field and to apply the catalyst at least six consecutive times without a significant decrease in conversion. Remarkable and excellent turnover frequency of the catalyst was obtained to oxidize the thioanisole (526,000 h −1 ), dimethyl sulfide (526,000 h −1 ), diallyl sulfide (526,000 h −1 ), dibutyl sulfide (521,000 h −1 ), and dipropyl sulfide (500,000 h −1 ). The prepared nanocatalyst has been beneficial in catalytic activity, selectivity, reaction time, and reusability with easy separation.

Green oxidation of sulfides in solvent-free condition by reusable novel Mo(VI) complex anchored on magnetite as a high-efficiency nanocatalyst with eco-friendly aqueous H2O2

In this research work, a novel molybdenum N4-type Schiff base complex anchored covalently on magnetite nanoparticles and characterized perfectly using physico-chemical techniques and it was applied for oxidation of sulfides. The effects of solvent, reaction temperature and amount of catalysts by 30% aqueous H2O2 as environmental friendly oxidant on oxidation catalytic process were optimized. The best results in solvent-free condition was obtained. The catalyst was tested for oxidation of thioanisole, Diphenyl sulfide, Benzyl phenyl sulfide, dipropyl sulfide, dibutyl sulfide, dimethyl sulfide, bis(4-hydroxyphenyl) sulfide, diallyl sulfide and benzothiophene. The presented nanocatalyst is so effective for selective oxidation of thioanisole, dimethyl sulfide, dibutyl sulfide and diallyl sulfide with a >99% conversion, and excellent turnover frequency (93,000h−1<) in shortest time (5min). The magnetic nanocatalyst was easily recovered by using an external magnetic field and employed at least six successive times without significant decreasing in conversion.

Laser photolysis studies of ω-bond dissociation in aromatic carbonyls with a C-C triple bond stimulated by triplet sensitization.

We have prepared three types of carbonyl compounds, benzoylethynylmethyl phenyl sulfide (2@SPh), (p-benzoyl)phenylethynylmethyl phenyl sulfide (3@SPh) and p-(benzoylethynyl)benzyl phenyl sulfide (4@SPh) with benzoyl and phenylthiylmethyl groups, which are interconnected with a C-C triple bond and a phenyl ring. Laser flash photolysis of 3@SPh and 4@SPh in acetonitrile provided the transient absorption spectra of the corresponding triplet states where no chemical reactions were recognized. Upon laser flash photolysis of 2@SPh, the absorption band due to the phenylthiyl radical (PTR) was obtained, indicating that the C-S bond cleaved in the excited state. Triplet sensitization of these carbonyl compounds using acetone and xanthone was conducted using laser photolysis techniques. The formation of triplet 3@SPh was seen in the transient absorption, whereas the PTR formation was observed for 2@SPh and 4@SPh, indicating that the triplet states were reactive for the C-S bond dissociation. The C-S bond dissociation mechanism for 4@SPh upon triplet sensitization is discussed in comparison with those for 2@SPh and 3@SPh.

Structure-induced catalysis enhancement of Cu-amino catalysts for rapidly selective oxidation of sulfides in the presence of H2O2

A Cu-amino coordination polymer promotes rapid sulfoxidation of benzyl phenyl sulfide toward the sulfoxide with high conversion and selectivity.

ChemInform Abstract: Bimetallic Titanium Complex Catalyzed Enantioselective Oxidation of Thioethers Using Aqueous H2O2 as a Terminal Oxidant.

A series of dimeric amino alcohol derived Schiff bases with various chiral amino alcohols and their corresponding bimetallic titanium complex were generated in situ. Thereafter with the in situ generated complexes, the asymmetric oxidation of prochiral aryl alkyl sulfides has been investigated using aqueous H2O2 as a terminal oxidant. During the study we found that the use of methanol or tert-butanol as an additive improved the catalytic activity in terms of both conversion and enantioselectivity. Moreover we observed a co-operative effect of the two reactive units of the bimetallic complex, which results in high reactivity as well as enantioselectivity compared to the corresponding monomeric complex. With this improved catalytic system several aryl alkyl sulfides and 1,3-dithianes were oxidised to the corresponding sulfoxides with good to high enantioselectivity (ee 78–99%) and conversion (70–99%). Unlike the monomer, oxidation of substrates like benzyl phenyl sulfide was achieved with high enantioselectivity as well as high yield.

Peroxo-dimolybdate catalyst for the oxygenation of organic sulfides by hydrogen peroxide

The reaction between Na2MoO4 and hydrogen peroxide at pH around 6.5 resulted in a novel peroxo-dimolybdate anion [{MoO(O2)2}2(μ-O)]2−, which was isolated as a tetrabutylammonium salt (1). X-ray single crystal diffraction study of 1 revealed that there are two η2-peroxo ligands for each Mo center and a single μ-oxo bridge linking two Mo(VI) centers. Compound 1 can function as a stoichiometric oxidant for the oxygenation of organic sulfides and donate up two active oxygen atoms. Furthermore, 1 catalyzes organic sulfide oxygenation by hydrogen peroxide with 100% utility. The catalytic proficiency of 1 was examined with the oxygenation reactions of substrates including benzyl phenyl sulfide, methyl phenyl sulfide and 4-bromo thioanisole with TOF of 240, 550 and 740h−1, respectively. Based on the initial rate study of several para-substituted thioanisoles, a reactivity constant (ρ) of −1.06 was obtained, which implies an electron deficient transition state. The initial rate study using thioanisole as the substrate also revealed that the reaction is first order in catalyst but zero order in hydrogen peroxide. Based on these results, a mechanism for the activation of hydrogen peroxide is proposed. The DFT calculations of model catalyst and substrate resulted in an activation energy of 75kJmol−1 for the transition state, and a reaction free energy of −69kJmol−1.

An Ultra-low-cost Route to Mesostructured TS-1 Zeolite for Efficient Catalytic Conversion of Bulk Molecules

Developing a low-cost route to synthesize mesoporous TS-1 (MTS-1) is of great importance because of its practical application in industry. Herein, we first synthesized a copolymer containing quaternary ammonium groups by a mesoporous template comprising inexpensive starting materials. Subsequently, waterglass (sodium metasilicate), TiCl3, and copolymer were dispersed in the preformed seeds emulsion, resulting in a gel for synthesizing MTS-1. The counterpart material (CTS-1) was also synthesized by the same procedure except for the absence of the copolymer. Compared with CTS-1, the MTS-1 exhibits good crystallinity and well-defined tetrahedral coordinated Ti species (TiIV) in the framework as well as excellent catalytic activity in the oxidation of bulky molecules, such as dibenzothiophene and benzyl phenyl sulfide. This feature may be attributed to the fact that the quaternary ammonium groups on copolymer facilitates the formation of the MFI structure and energetically incorporates the Ti species into the framework.

ChemInform Abstract: Rhodium‐Catalyzed Denitrogenative [2,3] Sigmatropic Rearrangement: An Efficient Entry to Sulfur‐Containing Quaternary Centers.

AbstractA convenient protocol is developed for the denitrogenative [2,3] sigmatropic rearrangement of triazoles with allyl sulfides and benzylphenyl sulfide.

Rhodium‐Catalyzed Denitrogenative [2,3] Sigmatropic Rearrangement: An Efficient Entry to Sulfur‐Containing Quaternary Centers

A convenient protocol is developed for the denitrogenative [2,3] sigmatropic rearrangement of triazoles with allyl sulfides and benzylphenyl sulfide.

Investigation of steric and electronic effects in the copper-catalysed asymmetric oxidation of sulfides

Steric and electronic effects in the copper-catalysed asymmetric oxidation of aryl benzyl, aryl alkyl and alkyl benzyl sulfides have been investigated. The presence of an aryl group directly attached to the sulfur is essential to afford sulfoxides with high enantioselectivities, with up to 97% ee for 2-naphthyl benzyl sulfoxide, the highest enantioselectivity achieved to date for copper-catalysed asymmetric sulfoxidation. In contrast, the benzyl substituent can be replaced by sterically comparable groups with no effect on enantioselectivity. Copper-mediated oxidation of substituted aryl benzyl sulfides display modest steric and electronic effects resulting in comparable or lower enantioselectivities to those obtained with the unsubstituted benzyl phenyl sulfide.

Transcyclopalladation on silica gel

A possibility of transcyclopalladation on silica gel was shown using reactions of acetato- and chloro-bridged dimeric cyclopalladated complexes derived from N,N-dimethylbenzylamine with benzyl methyl sulfide, benzyl phenyl sulfide, benzyldiphenylphosphine, 8-methylquinoline and 1,3-bis(methylthiomethyl)benzene in the presence of equimolar amount of CF3CO2H. The reaction provided the corresponding C,S-, C,N-, C,P- and S,C,S-palladacycles in 39–65% yield.