A simple acylation of thiols with anhydrides

Different thiols were efficiently acylated at room temperature with different anhydrides in the presence of potassium carbonate. Chemoselective protection of thiol in the presence of hydroxy group was achieved using di-tert-butyl dicarbonate and isatoic anhydride.     

Transition-metal-catalyzed carbonylation of allenes with carbon monoxide and thiols

In the presence of a catalytic amount of tetrakis(triphenylphosphine)platinum(0), allenes undergo carbonylative thiolation with carbon monoxide and thiols to provide the corresponding α,β- and β,γ-unsaturated thioesters in good yields. In contrast, the use of rhodium(I) catalysts such as RhH(CO)(PPh₃)₃ in place of Pt(PPh₃)₄ leads to copolymerization of allenes and carbon monoxide without incorporation of thio groups.     

A general rhodium-catalyzed cross-coupling reaction of thiols with aryl iodides

The general procedure for the rhodium-catalyzed cross-coupling of thiols with aryl iodides is described. The catalytic system consists of 5 mol % of [RhCl(cod)]₂ and 10 mol % of PPh₃ as a ligand. A variety of aryl iodides reacted with thiols, giving aryl thioethers in good to excellent yields. It is important to note that the deactivated aryl iodides such as 4-iodoanisole is worked smoothly to provide the corresponding aryl thioethers in excellent yields. Functional groups such as free-amines, chloro, are all tolerated under the employed reaction conditions.     

A general and efficient method for the palladium-catalyzed cross-coupling of thiols and secondary phosphines

The general and efficient cross-coupling of thiols with aryl halides was developed utilizing Pd(OAc)₂/1,1′-bis(diisopropylphosphino)ferrocene as the catalyst. The substrate scope is broad and includes a variety of aryl bromides and chlorides, which can be coupled to aliphatic and aromatic thiols. This catalyst system has the widest substrate scope of any reported to date. The present catalyst system also enables the palladium-catalyzed coupling of secondary phosphines with aryl bromides and chlorides.     

Oxidative transformation of thiols to disulfides promoted by activated carbon-air system

Efficient oxidative transformation of thiols to disulfides took place in the presence of activated carbon under an oxygen (or air) atmosphere. The present oxidation method is available not only for a variety of thiols such as simple aromatic and aliphatic thiols but also for 3,4-dihydropyrimidin-2(1H)-thiones and N-Boc-l-cysteine.     

Regioselective ring-opening of aziridines with potassium thiocyanate and thiols using sulfated zirconia as a heterogeneous recyclable catalyst

Ring-opening of aziridines with potassium thiocyanate and thiols has efficiently been carried out at room temperature in the presence of sulfated zirconia to give the corresponding β-aminothiocyanates and β-aminosulfides, respectively, in high yields within 2 h and with high regioselectivity. The catalyst, a solid acid, functions under heterogeneous conditions.     

Comparison of micro-LC and capillary zone electrophoresis for the analysis of thiols

Micro-LC and capillary zone electrophoresis (CZE) are two of the most rapidly developing, miniaturized separation techniques in analytical science. In the present paper, both techniques were comparatively evaluated for the determination of several important thiols derivatized with the fluorogenic reagent SBD-F. Different parameters, such as selectivity, sensitivity, analysis time and efficiency, influence of column length, CZE buffer concentration, and voltage were thus analyzed and discussed. Both techniques are recommended for the analysis of thiols in biological samples.     

Pd2(dba)3/Xantphos-catalyzed cross-coupling of thiols and aryl bromides/triflates

The cross-coupling of aliphatic and aromatic thiols and aryl bromides/triflates mediated by a Pd₂(dba)₃/Xantphos catalytic system in refluxing xylene (140 °C) affords the corresponding aryl thioethers in good to excellent yields.     

A colorimetric chemosensor for fast detection of thiols based on intramolecular charge transfer

A TCNQ-based triphenylamine derivative (1) with strong intramolecular charge transfer (ICT) character was designed as a colorimetric sensor for thiols. Upon addition of thiols, the absorption spectrum of sensor 1 in aqueous solution was remarkably changed because the adduct of 1 with thiol decreased its ICT character. Sensor 1 showed highly selective and sensitive sensing ability toward thiols over other analytes. This selectivity could be easily observed by naked eyes, indicating that sensor 1 is a potential colorimetric sensor for thiols.     

密度泛函理论研究碳链长度对氯化三烷基铵萃取氯化汞的影响

运用密度泛函理论方法研究了烷基碳链长度对氯化三烷基铵络合氯化汞的影响,计算结果表明,氯化三烷基铵与氯化汞的络合作用随着氯化三烷基铵中烷基碳链的增长而增强.通过对络合物的键长、Mayer键级和Mulliken电荷分析可知,电子富集在氯化三烷基铵的Cl原子上,并和Hg原子之间形成静电吸引作用.当烷基长度小于3时,烷基的电子效应影响较为明显,增强了原子之间的电子转移,使得络合物更稳定;当氯化三烷基铵烷基碳链长度大于3后,烷基链长对络合物中的电子转移不再有影响,络合物的稳定性受到烷基的几何效应影响更为明显.     

Selective and mild oxidation of thiols to sulfonic acids by hydrogen peroxide catalyzed by methyltrioxorhenium

Aromatic and aliphatic thiols are oxidized in acetonitrile at 20 °C by hydrogen peroxide in the presence of methyltrioxorhenium as the catalyst to yield the corresponding sulfonic acids in high isolated yields (85-94%).     

A simple, base-free preparation of S-aryl thioacetates as surrogates for aryl thiols

A mild method for the preparation of S-aryl thioacetates by hetero cross-coupling reactions of aryl bromides or aryl triflates with potassium thioacetate is described. The reaction proceeded smoothly in toluene at 110 °C, mediated by catalytic Pd₂(dba)₃ in combination with CyPF-tBu as the ligand. Neither the presence of a base nor microwave conditions were required. The formed S-aryl thioacetate proved to be stable under flash chromatographic conditions and could be rapidly converted into the corresponding thiol under mildly basic conditions.     

Investigation of the interaction between arsenic species and thiols via electrospray ionization tandem mass spectrometry

Arsenic species have been known to participate in a number of chemical and biological reactions, including oxidation-reduction reactions, acid-base reactions, covalent interactions, and methylation-demethylation reactions because of the element's multiple and interconvertible oxidation states. Little is known about the structure or bonding behavior between arsenic species and thiolcontaining biomolecules. Therefore, a better understanding of the bonding behavior and detailed information on the molecular structure for arsenic-thiol complexes is needed. As a result, we have investigated the interaction between arsenic species (arsenate (As^V), arsenite (As^III), monomethylarsonic acid (MMA^V), and dimethylarsinic acid (DMA^V)) with biomolecules containing thiol groups (glutathione and cysteine) by electrospray ionization mass spectrometry (ESI-MS). These compounds were dissolved in methanol/water solution and introduced into the MS instrument in order to elucidate the direct bonding behavior of thiol group of biomolecules with arsenic species. In addition, further detailed structural information on this complex was obtained by collision-induced dissociation (CID) measurements.In each mass spectrum for mixture solutions between arsenic species and thiol compounds, various peaks such as protonated arsenic-thiol complexes, protonated noncomplexed thiol compounds, sodium bound cluster ions, and proton bound cluster ions were observed. In these mass spectra, the arsenic complexes were formed by interaction with thiol groups on the cysteine residues. These arsenic-thiol complexes produced a variety of fragment ions by cleavage of chemical bonds, and by interaction of other binding site on thiol compounds in tandem mass spectrometry experiments.     

Transition-metal-free O-, S-, and N-arylation of alcohols, thiols, amides, amines, and related heterocycles

A new protocol for the Ullmann-type arylation process of different aromatic heterocycles without any transition-metal catalyst, implying the use of a combination of an excess of potassium hydroxide and dimethyl sulfoxide, is described. The reaction can be performed between a broad range of starting nucleophiles including phenol, alcohols, amines, nitrogen-containing five-membered systems such as pyrazoles, imidazoles, and indoles, and amides with haloarenes, iodide and bromide derivatives giving the best results, the possible pathway involving the in situ generation of the corresponding benzyne intermediate. When the reaction was performed with 2-iodoaniline and either carboxamides or isothiocyanato derivatives, the corresponding benzoazole derivatives were obtained.     

Synthesis, characterization and electrochemical behavior of unsymmetric transition metal-terminated biphenyl ethynyl thiols

The synthesis of the biphenyl alkynyl thiols and thioesters R′-CC-C₆H₄-C₆H₄-SR (3: R′ = SiMe₃, R = C(O)Me; 4: R′ = SiMe₃, R = H; 5: R′ = H, R = C(O)Me) from I-C₆H₄-C₆H₄-SC(O)Me (1) is described. Molecules 1 and 5 have been used as starting materials in the synthesis of mono- and heterobimetallic transition metal complexes of type L_nM′-CC-C₆H₄-C₆H₄-SR (7: L_nM′ = Fc, R = C(O)Me; 8: L_nM′ = Fc, R = H; 10: L_nM′ = (Ph₃P)Au, R = C(O)Me; 14: L_nM′ = FcPPh₂-Au, R = C(O)Me; Fc = (η⁵-C₅H₅)(η⁵-C₅H₄)Fe; FcPPh₂ = (η⁵-C₅H₅)(η⁵-C₅H₄PPh₂)Fe). While complex 7is accessible by the Sonogashira cross-coupling of Fc-CCH (6) with 1, molecules 10 and 14 can be prepared by treatment of the thioester 5 with (Ph₃P)AuCl (9) and FcPPh₂-AuCl (13), respectively.The molecular solid state structures of 3, 7, 10 and 13-15 have been determined by single crystal X-ray crystallographic analysis. Typical features of these species are their linear M-CC-C₆H₄-C₆H₄-SR structure and the lack of coplanarity of the biphenyl arene rings. The overall length of these complexes are 13.345(2) Å for 3 (molecule A), 15.146(3) Å for 7, 15.705(2) Å for 10 (molecule A) and 15.649(4) Å for 14. The thioester groups are pointing away from the ferrocene building block. In 7 a linear 1D chain is set-up by π-interactions between two independent molecules of 7. Characteristic for 15 is the formation of a Au₂I₂ ring, while 13 is monomeric.All compounds were studied with cyclic voltammetry. Characteristic are the reversible ferrocene Fe(II)/Fe(III) redox wave, the irreversible reduction of Au(I) to Au(0), the oxidative cleavage of the S-C(O)Me sulfur-carbon (3, 5, 7, 10 and 14) and of the sulfur-hydrogen bond (4 and 8), respectively. Electronic effects extending from the -SH-end group to the ferrocene unit resulting in considerable shifts of the redox potential of the latter entity are found. Coordination of Au(I) at the FcPPh₂ moiety also results in a shift of the redox potential of the ferrocene group indicative of an electron withdrawing effect of the Au(I) species.     

Isopiestic measurements on aqueous mixtures of sodium chloride and strontium chloride

Isopiestic measurements have been made on NaCl–SrCl₂ mixtures at 25°C over the ionic strength range 0.6–6 mole-kg^–1. The results are interpreted in terms of current mixed-electrolyte treatments. The mixing behavior in this system is comparatively simple, but the Pitzer treatment is still clearly superior to the other treatments.     

The homologous conjugate addition of thiols to electron-deficient cyclopropanes catalyzed by a calcium(II) complex

The synthesis of γ-sulfanyl malonates was achieved through the addition of thiols to electron deficient cyclopropanes. These reactions are catalyzed by calcium acetylacetonate, Ca(acac)₂. A variety of electron rich and electron deficient thiols were added without the need for prior activation or exogenous base. The thiol additions to donor–acceptor cyclopropanes bearing electron-rich and electron-deficient aromatic and heteroaromatic groups proceeded in good to excellent yields.