Some Comments on the Conformations of Methyl Phenyl Sulfides,Sulfoxides and Sulfones

¹³C-NMR. and He (Iα) photoelectron spectra of alkyl phenyl sulfides, sulfoxides and sulfones have been used to probe how their conformations depend on the size of the alkyl groups R. The results are interpreted to indicate that in the sulfides the S, R-bond is twisted out of the planar conformation with increasing size of the alkyl group, whereas in the sulfoxides and sulfones the preferred conformation with the S, R-bond perpendicular to the phenyl group plane seems to be independent of the size of R. These conclusions are in agreement with previous work on the alkyl phenyl sulfides and provide strong support for previous conjectures concerning the preferred conformations of alkyl phenyl sulfoxides and sulfones.     

Chiral sulfoxides from (R)-α- dimethylaminoethylferrocene

Chiral sulfoxides and sulfones of potential interest in organic synthesis are prepared by the reaction of 2-lithio-1-(dimethylaminoethyl)-ferrocene with disulfides, followed by oxidation of the sulfides thus obtained with sodium metaperiodate on alumina or with 3-chloropcrbenzoic acid. Most of the reactions, in particular oxidations of the sulfides to form the sulfoxides, proceed with high diastereoselectivity. The sulfoxides and sulfones can be isolated as pure enantiomers. Assignment of absolute configurations is based on independent synthesis together with ¹H- and ¹³C-NMR data and ORD measurements.     

Synthesis of 3-Coumaryl Phenyl Sulfones or Sulfoxides

An unambiguous synthesis of a number of 3-coumaryl phenyl sulfones or sulfoxides have been described which were obtained by the oxidation of the corresponding sulfides with hydrogen peroxide. The sulfides were prepared by the Perkin-Oglialore reaction of o-hydroxyaldehyde with the sodium salt of different S-phenyl thioacetic acids. The sulfones did not exhibit any appreciable antitubercuious activity in the preliminary screening tests.     

Regioselective Synthesis of Benzofuran‐Annulated Six‐Membered Sulfur Heterocycles by Aryl Radical Cyclization

The tin hydride–mediated cyclization of a number of sulfides and sulfones under mild and neutral conditions has been investigated. The sulfides were in turn derived from 3(2H) benzothiofuranone and 2‐bromobenzyl bromides by phase‐transfer‐catalyzed reaction, and the corresponding sulfones were prepared by treatment of the corresponding sulfides with m‐CPBA at room temperature. The sulfides and sulfones were then reacted with ⁿ Bu₃SnH‐AIBN to afford regioselectively benzofuran‐annulated six‐membered sulfur heterocycles.     

Evidence of Two Key Intermediates Contributing to the Selectivity of P450‐Biomimetic Oxidation of Sulfides to Sulfoxides and Sulfones

A mild process for the selective oxidation of sulfides is in great demand. Therefore, probing the mechanism underlying the biological oxidation of sulfides under ambient conditions may provide valuable insights for the development of such a reaction. Based on porphyrin models of P450 enzymes, evidence of two key intermediates, Int0 and Int1 , in this reaction is provided. Spectroscopic studies indicated the formation of a hydroperoxide‐iron(III) species ( Int0 ) upon addition of H₂O₂. This intermediate proved to be highly selective for sulfoxide production. By contrast, a defined porphyrin oxoiron(IV) cation radical ( Int1 ) directly reacted with sulfoxides, leading selectively to the corresponding sulfones. Interestingly, the available sulfoxides reversibly act as a new axial ligand for Int0 forming a more active species Int0 _SO. The amount of Int0 increased in the presence of alkyl, aryl, or aromatic sulfides, while Int1 formed in the absence of these sulfides. Thus, sulfoxides and sulfones would selectively form under conditions that favor the corresponding intermediates, which elucidate the biological oxidation pathway.     

Regioselective Synthesis of 1,8-Naphthyridinone-Annulated Oxygen and Sulfur Heterocycles by Tri-n-butyl Tinhydride–Mediated Aryl Radical Cyclization

The tin hydride–mediated cyclizations of a number of ethers, sulfides, and sulfones under mild, neutral conditions have been investigated. While the 2-bromobenzyloxy ethers were prepared in 62–65% yields by the alkylation of 4-hydroxy-1-phenyl-1,8-naphthyridin-2(1H)-one with 2-bromobenzyl bromides in refluxing acetone in the presence of anhydrous potassium carbonate, the sulfides were derived from 4-mercapto-1-phenyl-1,8-naphthyridin-2(1H)-one and 2-bromobenzyl bromides in 82–84% yields by a phase-transfer catalysis (PTC) reaction. The corresponding sulfones were prepared by treatment of the sulfides with m-CPBA in refluxing dichloromethane. The ethers, sulfides, and the sulfones were treated with ⁿ Bu₃SnH-AIBN to give regioselectively 1,8-naphthyridinone-annulated oxygen and sulfur heterocycles in 70–78% yields.     

Products of Reaction of Tricyclo[4.1.0.02,7]heptane and 1-Bromotricyclo[4.1.0.02,7]heptane with Hydrogen Sulfide,and Syntheses Based Thereon

By reactions of 1-R-tricyclo[4.1.0.02,7]heptanes (R = H, Br) with hydrogen sulfide initiated by UV irradiation endo-6-bicyclo[3.1.1]heptanethiols and bis(endo-6-bicyclo[3.1.1]heptyl) sulfides were synthesized. The sulfides were oxidized to the corresponding sulfoxides and sulfones. The results of HBr elimination from the bromine-substituted sulfoxides and sulfones effected by potassium tert-butylate are discussed. The latter reaction results in the recovery of the system of 1-substituted tricyclo[4.1.0.02,7]heptane.     

New type of fragmentation of organic cation-radicals in a strong electrical field

A new type of fragmentation of organic cation radicals of sulfides, sulfoxides, and sulfones, leading to the elimination of S⁺, SO⁺ and SO ₂ ⁺ ions, respectively, has been discovered, and the possible mechanisms of their formation have been proposed. The most probable is a mechanism by which a cleavage of two C-S bonds takes place in the cyclic transition complex and formation of one C-C bond due to the recombination of the radicals. The line of the ion with a mass of 32 amu present in the spectra of almost all the sulfoxides studied, was assigned to the sulfur ion, formed by a similar mechanism after the displacement of alkyl or aryl residue in the molecular ion from sulfur to oxygen. Signs of such a migration also appear in the mass spectra of certain sulfones.Translated from Teoreticheskaya i Éksperimental'naya Khimia, Vol. 21, No. 6, pp. 730–735, November–December, 1986.     

Dissociation and rearrangements of the molecular ions of sulfides,sulfoxides, and sulfones generated by a strong electric field

The field mass spectra of 18 sulfides, sulfoxides, and sulfones were investigated, and the principles of charge localization in the dissociation and rearrangements of the molecular ions of these compounds were established. A new type of fragmentation leading to the elimination of S^+., SO^+., and SO₂. was observed. A new mechanism, according to which cleavage of two C-S bonds and the formation of one new C-C bond due to radical recombination cocur in the cyclic transition complex, is proposed. Prior migration of alkyl radicals from sulfur to oxygen with subsequent cleavage of the S-O and C-S bonds via the above-mentioned mechanism may also occur in the molecular ions of sulfoxides and sulfones.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 23, No. 2, pp. 172–181, March–April, 1987.     

The mass spectra of thiochromanone and related compounds

The mass spectra of thiochromanone (I), isothiochromanone (II)-2-, 3- and 8-methylthiochromanone and the sulfoxides and sulfones derived from these cyclic sulfides have been determined and the major fragmentation routes established. For the iso series loss of SO or SO₂ competes effectively with the retro-Diels-Alder reaction; however, for the thiochromanone derivatives the retro-Diels-Alder reaction is the major fragmentation route. There is no evidence for rearrangement of the sulfoxides or sulfones to sulfenates or sulfinates, respectively, prior to fragmentation.     

Selective Oxidation of Sulfides to Sulfoxides/Sulfones by 30% Hydrogen Peroxide

Abstract

A selective and efficient procedure for the oxidation of various sulfides with sodium tungstate dihydrate with 30% hydrogen peroxide in the presence of trioctylmethylammonium dihydrogen phosphate, respectively, to the corresponding sulfoxides and sulfones is reported. The oxidation reaction is carried out at –5 to 0 °C in the presence of hydroxypropyl-β-cyclodextrins for sulfoxides or at 50–60 °C for sulfones. The mild reaction conditions, easy workup, and good yields of the products are the major advantages of this method.     

Fragmentation in chemical ionization mass spectrometry and the proton affinity of the departing neutral

Chemical ionization mass spectra of six 5,6-dihydro-2-methyl-1,4-oxathiins, and some of the sulfoxides and sulfones derived therefrom, have been determined employing hydrogen, methane and isobutane as reagent gases. The major fragmentation reaction of the protonated molecule, [R′COX·H]⁺, involves loss of the neutral HX molecule. For the sulfides and sulfones, with X ranging from OH to N(CH₃)C₆H₅, it is observed that the importance of this fragmentation is inversely correlated with the proton affinity of the departing HX molecule in both the H₂ and CH₄ chemical ionization. For the sulfoxides no consistent correlation is observed and this is attributed to the interference of competing and/or consecutive fragmentation reactions. In the isobutane chemical ionization mass spectra only the protonated molecule is observed for most of the compounds studied.     

Reactions of halometal alkoxides

Aryl thenyl and aryl aryl-α-thienylmethyl sulfides have been obtained by the action of oxalic acid esters on an equimolecular mixture of bromomagnesium thienyl or aryl α-thienyl carbinolates and bromomagnesium thiophenolates (or thionaphtholates). Derivatives of the sulfides, sulfoxides and sulfones, are also described.     

Tandem mass spectra of divalent metal ion adducts of glycosyl sulfides, sulfoxides and sulfones; distinction among stereoisomers

The tandem mass spectra of the divalent metal ion (Mg2+, Ca2+, Sr2+, Ba2+, Mn2+, Ni2+, Co2+ and Zn2+) adducts of acetylated 1,2-trans-glycosyl sulfides, sulfoxides and sulfones were examined using low energy collision-induced dissociation on a Quattro II quadrupole tandem mass spectrometer. Abundant doubly charged ions, such as [3M + Met]2+ and [2M + Met]2+, were observed with alkaline earth metal chlorides. The other ions observed were [M + MetCl]+, [M + MetOAc]+, [M + MetO2SPh]+ and [2M + MetCl]+. The deprotonated metal adducts [M + Met-H]+ were seen only in the sulfones. The divalent metal ion adducts showed characteristic fragmentation pathways for the glycosyl sulfides, sulfoxides and sulfones, depending on the site of metal attachment. The doubly charged metal ion adducts dissociate to two singly charged ions, [M + MetOAc]+ and [M - OAc]+, in the sulfides and sulfoxides. In the sulfones, the adducts dissociate to [M + MetO2SPh]+ and [M - O2SPh]+. In contrast to the alkaline earth metals, which attach to the acetoxy functions, the transition metals attach to the sulfide and sulfoxide functions. The metal chloride adducts display characteristic fragmentation for the sulfides, sulfoxides and sulfones. The glucosyl, mannosyl and galactosyl sulfides, sulfoxides and sulfones could be differentiated on the basis of the stereochemically controlled MS/MS fragmentations of the metal chloride adducts.     

Synthesis and carbon-13 nuclear magnetic resonance spectroscopy of 5,6-dihydro-2-methyl-1,4-oxathiin,trans-tetrahydro-1,4-benzoxathiin, 1,4-tetrahydro-[9,10]benzoxathiin,the 4-oxides, 4,4-dioxides and related acyclic compounds

The results of a ¹³C NMR spectral investigation involving 5,6-dihydro-1,4-oxathiins, 1,4-tetrahydro[9,10]benzoxathiin, trans-tetrahydro-1,4-benzoxathiin, and the corresponding sulfoxides and sulfones are reported. An interpretation involving a dipolar structure with (2p→2p)π conjugation as opposed to (2p→3d)π interactions with the vinyloxy sulfides seems consistent with trends in the ¹³C NMR shifts. For the sulfoxides and sulfones, the substitutent-induced chemical shift (SCS) effects at the β vinylic carbons (βSO and βSO₂ effects) are considerably less than those at sp³ carbons. The γSO and γSO₂ values at the sp²γ carbons indicate deshielding, in contrast to the shielding at the sp³ carbons.     

1,1,2,2-Tetrahydroperoxy-1,2-diphenylethane as new oxidant for chemoselective and catalyst free oxidation of sulfides to sulfoxides and sulfones

A catalyst free and chemoselective oxidation of sulfides to sulfoxides or sulfones was developed using 1,1,2,2-tetrahydroperoxy-1,2-diphenylethane as a new oxidant. This scope has shown the achievement of various sulfoxides and sulfones which were obtained selectively in high yields at room temperature.     

Neue Synthesemethoden, 4. Mitt.: Milde einphasenoxidation von Sulfiden und Sulfoxiden zu Sulfonen

The mild oxidation of sulfides and sulfoxides to sulfones with benzyltriethylammoniumpermanganate in organic solvents is described.

1Scholz, D., in Vorbereitung.     

Oxidation of Sulfides with Hydrogen Peroxide to Sulfoxides and Sulfones

Oxidation of sulfides with hydrogen peroxide to sulfoxides and then sulfones was studied. The conditions optimal for the formation of sulfoxides and sulfones were found.     

Selective oxidation of sulfides to sulfoxides and sulfones at room temperature using H2O2 and a Mo(VI) salt as catalyst

Selective oxidation of sulfides to sulfoxides and sulfones is achieved by H₂O₂ using MoO₂Cl₂ as the catalyst. Various substituted sulfides having functional groups such as methyl, methoxy, bromo, nitro, alkene, alkyne, alcohol, ester, aldehyde and remarkably an oxime are successfully and selectively oxidized without affecting the sensitive functionalities.     

Selective Oxidation of Sulfides to Sulfoxides and Sulfones Using n -Butyltriphenylphosphonium Dichromate (Bu n PPh3)2Cr2O7 in the Presence of Aluminium Chloride in Solution and Under Microwave Irradiation

A wide variety of sulfides are efficiently oxidized to their corresponding sulfoxides and sulfones in excellent yields using n-butyltriphenylphosphonium dichromate (BTPPDC) in the presence of aluminium chloride in acetonitrile solution and under microwave irradiation. In addition, selective oxidation of sulfides in the presence of functional groups such as a carbon–carbon double bond, ketone, oxime, aldehyde, ether, and acetal can be considered as a noteworthy advantage of this method.