ANODIC OXIDATION OF 1,n-HALO(ALKYLTHIO)ALKANES AND 1,n-CHLORO(ALKYLSULFINYL)ALKANES

Abstract

Anodic oxidation of 1,n-halo(alkylthio)alkanes [X-(CH₂)_n-S-R, X = Cl, Br, I] and l,nhalo(alkylsulfinyl)alkanes [Cl-(CH₂)_n-S(O)-R] was studied by cyclic voltammetry in anhydrous acetonitrile and by controlled potential electrolyses. The ease of sulfur oxidation was not affected by the alkyl substituents R or the number of methylene groups n in compounds with n > 2. The oxidation of the 1,2-halo(alkylthio)ethanes (n = 2) occurred at slightly higher potentials. The peak potentials decreased slightly in the order Cl > Br > I which is probably due to the electronegativity of the halogen atoms. The investigated anodic oxidation was shown to be a two electron irreversible process. Electrolyses in aqueous acetronitrile led to the corresponding sulfoxides and sulfones in good yields.     

Oxidation of sulfide with ArIO catalyzed with TPPM(III)Cl

Various sulfides were easily converted to the corresponding sulfoxides in high yields in TPPM(III)Cl-catalyzed oxidation with ArIO, to which the influence of structures of sulfides and iodosylaromatics, and kinds of metals centered on the catalysts were investigated.     

REDUCTIVE DEIMINATION OF SULFOXIMIDES AND SULFIMIDES WITH P-TOLUENESULFONYL NITRITE AND T-BUTYL THIONITRATE1

Abstract

Reduction of sulfimides and sulfoximides with p-toluenesulfonyl nitrite, a new nitrosating agent, gave nearly quantitatively the corresponding deimination products, sulfides and sulfoxides, respectively. In the reaction of dialkyl and aryl alkyl sulfoximides with t-butyl thionitrate, N-t-butylthiosulfoximides were obtained besides the usual deimination products, although diaryl sulfoximides were readily deiminated to the corresponding sulfoxides in good yields in the same treatment. t-Butyl thionitrate was also found to deiminate diphenyl sulfimide to give diphenyl sulfide in good yield. Sulfoximides reacted sluggishly with t-butyl thionitrite, however, eventually affording a small amount of sulfoxides.     

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.     

POLY(p-DIOXANONE) AND ITS COPOLYMERS

ABSTRACT

This paper reviews the synthesis, properties, and applications of biodegradable polymer, poly(p-dioxanone) (PPDO), and its copolymers. Recent progress in ring-opening polymerization of p-dioxanone employing several effective catalysts is described. Properties of PPDO are given. The copolymers based on PPDO are also discussed.     

Asymmetric oxidation of sulfides catalyzed by (R)-6,6'-dibromo-BINOL derived titanium complex

Abstract

An efficient asymmetric oxidation of sulfides was achieved using (R)-6,6'-dibromo-BINOL as chiral ligand in combination with Ti(OⁱPr)₄ using 70% aqueous tertiary butyl hydroperoxide as oxidant. The resulting sulfoxides had high enantiopurities and good yields. A range of aryl alkyl and aryl benzyl sulfides were oxidized to the corresponding sulfoxides with 78–95% ee in 72–80% yields.     

Pseudoesters and Derivatives. XXXI1. Synthesis of 5-Ethylthio-, 5-Ethylsulfinyl- and 5-Ethylsulfonylfuran-2(5H)-ones

Convenient syntheses of 5-(ethylthio) furan-2(5H)-ones 2a-k from the appropriate 5-methoxyfuran-2(5H)-one 1a-g are described. The oxidation to the corresponding sulfoxides 5a-c and sulfones 6a-f is also reported.     

One-Pot Synthesis and Asymmetric Oxidation of 2-Nitro-4-(Trifluoromethyl)Benzene Containing Sulfides

Abstract

An efficient one-pot method for the preparation of 2-nitro-4-(trifluoromethyl)benzene containing sulfides from 1,1′-disulfanediylbis[2-nitro-4-(trifluoromethyl)benzene] is proposed. The corresponding enantiomerically enriched sulfoxides with up to 78% enantiomeric excess are prepared by the asymmetric oxidation of sulfides using a modified Sharpless method. The yield of sulfoxides is shown to decrease with an increase in the bulk of the aliphatic group and with a decrease of the inductive effect of the hydrocarbonic moiety on the sulfur atom.

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GRAPHICAL ABSTRACT      

SYNTHESES AND SOME PROPERTIES OF SULFOXIDES,SULFILIMINES, AMINOSULFONIUM SALTS AND SULFOXIMINES CONTAINING PYRIDINE NUCLEI

Abstract

Several 2-pyridyl sulfides (1) (e.g., methyl (1a), ethyl (1b), isopropyl (1c), benzyl (1d), 1-phenylethyl (1e), l-menthyl (If) 2-pyridyl sulfides; and bis(2-pyridylthio)methane (1g), and methyl 2-(N-oxy-pyridyl) sulfide (1h) were prepared by the usual method. Sulfoxides (2) were prepared by oxidation of the corresponding sulfides with m-chloroperbenzoic acid in good yields. A few sulfoxides were found to work as phase-transfer catalysts for some typical nucleophilic reactions in nonpolar solvents such as benzene, and in two-phase systems such as benzene-water. S-2-Pyridyl-N-(p-toluenesulfonyl) sulfilimines (3) were prepared upon treatment of sulfides with Chloramine-T. Hydrolysis of N-(p-toluenesulfonyl)-2-pyridyl-o-tolylsulfilimine (3i) with conc. sulfuric acid gave the corresponding free sulfilimine in a moderate yield. S-2-Pyridyl sulfoximines (4) were not obtained by the general method from the sulfoxides and hydrazoic acid. Alkyl-2-pyridyl sulfoximines, however, were obtained by oxidation of the free sulfilimines derived from the corresponding aminosulfonium salts (5) prepared by reaction of the sulfides with mesitylene-sulfonylhydroxylamine (MSH). These free sulfilimines and sulfoximines thus prepared were found to give adducts with a few copper salts.     

One-step Oxidative Monofluorination of Electron-Deficient Sulfoxides to Access Highly Lewis Acidic Sulfur(VI) Cations

The strongly oxidizing, powerful electrophilic fluorination reagent [FXe][OTf] is shown to effect direct oxidative monofluorination of sulfoxides. This one-step, chloride promoter-free methodology provides access to so far inaccessible, yet highly desirable strongly Lewis acidic fluorosulfoxonium cations from electron-deficient and/or sterically demanding sulfoxides that are shown to be practically unreactive towards the previously reported XeF₂/NEt₄Cl system. Experimental and density functional theory studies have been conducted to assess the Lewis acidities of the prepared sulfur(VI) cations. Preliminary results obtained with chiral sulfoxides provide early insights into the mechanism of these fluorination reactions.     

Selective and Reversible Solvent Uptake in Tetra-4-(4-pyridyl)phenylmethane-based Supramolecular Organic Frameworks

The dynamic behavior of supramolecular organic frameworks (SOFs) based on the rigid tetra-4-(4-pyridyl)phenylmethane ( TPPM) organic tecton has been elucidated through 3D electron diffraction, X-ray powder diffraction and differential scanning calorimetry (DSC) analysis. The SOF undergoes a reversible single-crystal-to-single-crystal transformation when exposed to vapours of selected organic solvents, moving from a closed structure with isolated small voids to an expanded structure with solvated channels along the b axis. The observed selectivity is dictated by the fitting of the guest in the expanded SOF, following the degree of packing coefficient. The effect of solvent uptake on TPPM solid-state fluorescence was investigated, evidencing a significant variation in the emission profile only in the presence of chloroform.     

trans‐Dichloro(dimethyl sulfide‐κS)(pyridine‐κN)platinum(II)

The structure of the title compound, [PtCl₂(C₅H₅N)(C₂H₆S)], consists of discrete mol­ecules in which the Pt‐atom coordination is slightly distorted square planar. The Cl atoms are trans to each other, with a Cl—Pt—Cl angle of 176.60 (7)°. The pyridine ligand is rotated 64.5 (2)° from the Pt square plane and one of the Pt—Cl bonds essentially bisects the C—S—C angle of the di­methyl sulfide ligand. In the crystal structure, there are extensive weak C—H⋯Cl interactions, the shortest of which connects mol­ecules into centrosymmetric dimers. A comparison of the structural trans influence on Pt—S and Pt—­N distances for PtS(CH₃)₂ and Pt(pyridine) fragments, respectively, in square‐planar Pt^II complexes is presented.     

Zinc(II) and mercury(II) complexes with Schiff bases: syntheses,spectral, and structural characterization

Schiff bases o-vanilidene-1-aminobenzene (HL¹) and o-vanilidene-2-methyl-1-aminobenzene (HL²) lead to the formation of mono- and bis-[(Cl)Zn(L¹)] (1), [(Cl)Zn(L²)] (2), [(Cl)Hg(L¹)] (3), [(Cl)Hg(L²)] (4), [Zn(L¹)₂] (5), [Zn(L²)₂] (6), [Hg(L¹)₂] (7), and [Hg(L²)₂] (8) complexes by reactions of zinc(II) and mercury(II) chlorides in different mole ratio(s). Complexes 1–8 have been characterized by elemental analyses (Zn, Hg, C, H, Cl, and N), melting point and spectral (IR, ¹H-NMR), PXRD, molar conductivity measurement, and TGA. Conductivity measurements suggest non-electrolytes. Structural compositions have been assigned by mass spectral studies. Four-coordinate geometry may be assigned to these complexes tentatively. Structural study reveals that in 1–4 two metal centers are held together by two bridged (μ₂-Cl) chlorides, whereas 5–8 contain two bidentate Schiff-base ligands around one metal-producing monomers.     

A Simple and Selective Oxidation of Sulfides to Sulfoxides Using Tetrabutylammonium Peroxydisulfate: A Rebuttal

Abstract

The report that oxidation of sulfides to sulfoxides using tetrabutylammonium peroxydisulfate (2) in methylene chloride was found to be erroneous. We repeated the procedure described in the paper and found that oxidation of sulfide to sulfoxide could not be achieved with the method.     

THE REACTION OF ANHYDROUS HCI/CHLOROFORM WITH DIARYL SULFOXIDES

Abstract

The reaction of variously substituted diaryl sulfoxides with anhydrous HCl in chloroform was examined. The products ranged from the corresponding sulfides to mono- and dichlorinated sulfides and sulfoxides. The same reaction in the presence of phenol afforded primarily the corresponding sulfides accompanied by o- and p-chlorophenol. The latter reaction is an efficient means for deoxygenating diaryl sulfoxides. The mechanism of the reaction and the nature of the chlorinating species are discussed.     

Iridium (III) and rhodium (III) triazoles by 1,3-dipolar cycloadditons to a coordinated azide in iridium (III) and rhodium (III) compounds

The reaction of [(η⁵-C₅Me₅)M(μCl)Cl]₂ with the ligand (L^∩L) in the presence of sodium methoxide yielded compounds of general formula [(η⁵-C₅Me₅)M(L^∩L)Cl] (1–10) (where M = Ir or Rh and L^∩L = N^∩O or O^∩O chelate ligands). Azido complexes of formulation [(η⁵-C₅Me₅)M(L^∩L)N₃] (11–20) have been prepared by the reaction of [(η⁵-C₅Me₅)M(μN₃)(X)]₂ (X = Cl or N₃) with the corresponding ligands or by the direct reaction of [(η⁵-C₅Me₅)M(L^∩L)Cl] with NaN₃. These azido complexes [(η⁵-C₅Me₅)M(L^∩L)N₃] undergo 1,3-dipolar cycloaddition reaction with substituted alkynes in CH₂Cl₂ and for the first time in ethanol at room temperature to yield iridium (III) and rhodium (III) triazoles (21–28). The compounds were characterized on the basis of spectroscopic data, and the molecular structures of 2 and 26 have been established by single crystal X-ray diffraction.     

AN UNUSUAL RUTHENIUM(II) COMPLEX OF 2-(2-PYRIDYL)BENZOTHIAZOLE

Abstract

The ligand 2-(2-pyridyl)benzothiazole (L) can act both as an N-N and an N-S chelating donor. The latter coordination mode is expected to be preferred when it is involved in coordination to Ru(II) which is a soft acceptor centre However, in the title compound, chlorobis(acetonitrile)triphenylphosphino-2-(2-pyridyl)benzothiazole-N,N-ruthenium(II) chlride, [Ru(L)(PPh₃(CH₃CN)₂Cl]Cl, the ligand acts in N,N-bidentate manner and the Ru(II) ion is found to be present in an N₄PCl coordination environment. PPh₃ and Cl are trans to each other and the two CH₃CN ligands occupy cis positions facing the NN donor atoms of ligand L.     

Kinetics and mechanisms of catalytic oxygen atom transfer with oxorhenium(V) oxazoline complexes

The rhenium(V) monooxo complexes (hoz)2Re(O)Cl (1) and [(hoz)2Re(O)(OH2)][OTf] (2) have been synthesized and fully characterized (hoz = 2-(2'-hydroxyphenyl)-2-oxazoline). A single-crystal X-ray structure of 2 has been solved: space group = P1, a = 13.61(2) A, b = 14.76(2) A, c = 11.871(14) A, alpha = 93.69(4) degrees, beta = 99.43(4) degrees, gamma = 108.44(4) degrees, Z = 4; the structure was refined to final residuals R = 0.0455 and Rw = 0.1055. 1 and 2 catalyze oxygen atom transfer from aryl sulfoxides to alkyl sulfides and oxygen-scrambling between sulfoxides to yield sulfone and sulfide. Superior catalytic activity has been observed for 2 due to the availability of a coordination site on the rhenium. The active form of the catalyst is a dioxo rhenium(VII) intermediate, [Re(O)2(hoz)2]+ (3). In the presence of sulfide, 3 is rapidly reduced to [Re(O)(hoz)2]+ with sulfoxide as the sole organic product. The transition state is very sensitive to electronic influences. A Hammett correlation plot with para-substituted thioanisole derivatives gave a reaction constant rho of -4.6 +/- 0.4, in agreement with an electrophilic oxygen transfer from rhenium. The catalytic reaction features inhibition by sulfides at high concentrations. The equilibrium constants for sulfide binding to complex 2 (cause of inhibition), K2 (L x mol(-1)), were determined for a few sulfides: Me2S (22 +/- 3), Et2S (14 +/- 2), and tBu2S (8 +/- 2). Thermodynamic data, obtained from equilibrium measurements in solution, show that the S=O bond in alkyl sulfoxides is stronger than in aryl sulfoxides. The Re=O bond strength in 3 was estimated to be about 20 kcal x mol(-1). The high activity and oxygen electrophilicity of complex 3 are discussed and related to analogous molybdenum systems.     

Highly Enantiopure (tert-Butyldiphenylsilyloxymethyl)Oxiranes from Barium Carbonate

The synthesis of (2R)-(tert-butyldiphenylsilyloxymethyl)oxirane and the (2S)-enantiomer from barium carbonate was developed. Methyl glycolate or the hydroxamate analog was prepared and in turn reacted with (S)-(-)-methyl p-tolylsulfoxide or the (R)-enantiomer to make β-keto sulfoxides. From the sulfoxides, we made the diastereoisomeric alcohols in a highly selective sulfoxide group directed hydride reduction, and a Pummerer rearrangement reaction followed by deprotection yielded the enantiomeric diols. (2R)-(tert-Butyldiphenylsilyloxymethyl)oxirane and its (2S)-enantiomer were derived from these diols in an overall yield of 56% from barium carbonate. This method was developed to provide a convenient access to isotope-labeled analogs of these compounds.     

Synthesis,Characterization, Electrochemical and Spectroscopic Properties of [Ru(dppt)(bpy)Cl]+ and [Ru(pta)(bpy)Cl]+

Two novel Ru^II complexes [Ru(dppt)(bpy)Cl]ClO₄ (1) and [Ru(pta)(bpy)Cl]ClO₄ (2)[dppt, pta and bpy = 3-(1,10-phenanthrolin-2-yl)-5,6-diphenyl-as-triazine, 3-(1,10-phenanthrolin-2-yl)-as-triazino[5,6-f]acenaphthylene and 2,2-bipyridine, respectively] were synthesized and characterized by elemental analysis and electrospray mass spectrometry, ¹H-n.m.r., and u.v.–vis spectroscopy. The redox properties of the complexes were examined using cyclic voltammetry. Due to the strong -accepting character of asymmetric ligands, the MLCT bands of (1) and (2) are shifted significantly to lower energies by comparison with [Ru(tpy)(bpy)Cl]⁺.