Disulfide Adducts Research Articles

Areneruthenium complexes with S 2CPR 3 and trichlorostannate

Complexes [{(η 6-arene) RuCl 2} 2] (arene = benzene, p-cymene or hexamethylbenzene), react with trialkylphosphine-carbon disulfide adducts, S 2CPR 3 (R = cyclohexyl, Cy; or isopropyl, 1Pr), in refluxing ethanol in the presence of KPF 6 to afford cationic complexes [(η 6-arene) Ru(S 2CPR 3)Cl]PF 6, which have been characterized by analytical and spectroscopic methods. These complexes react with SnCl 2 in CH 2Cl 2/THF to afford trichlorostannato-derivatives [(η 6-arene)Ru(S 2CPR 3)(SnCl 3)]PF 6 through insertion of SnCl 2 into the RuCl bond.

Enzyme chemistry of [formula omitted]hemiacetals: Synthesis and characterization of [formula omitted]mandeloylglutathione as an alternate substrate for glyoxalase I

Both the D - and L -forms of S- dithio mandeloylglutathione (1) have been synthesized by a dithio ester-interchange reaction between GSH and S-carboxymethyl ( D , L )- dithio mandelate. Kinetic and product analysis studies indicate that yeast glyoxalase I efficiently catalyzes the stereoselective conversion of D -1 to GSH-phenylglyoxal dithio hemiacetal (2), isolated as a disulfide adduct between 2 and a second molecule of GSH. This observation suggests that dithio ester substrate analogues should be generally useful as mechanistic probes of enzyme catalyzed reactions involving thiohemiacetal intermediates.

Determination of double-bond positions in methylene-interrupted dienoic fatty acids by GC-MS as their dimethyl disulfide adducts

A method using GC-MS for determining the double-bond positions in methylene-interrupted dienoic fatty acids as their dimethyl disulfide adducts is described. As a standard procedure for the single-step preparation of the adducts, methyl linoleate was subjected to the I 2-catalyzed reaction with dimethyl disulfide for 30 min. After the addition of a hexane/ether mixture and an aqueous Na 2S 2O 3 solution to reduce I 2, the resulting adducts in the upper phase were analyzed directly by GC-MS. The adducts consisted of an equimolar mixture of methyl 9,10-bis(methylthio)octadec-12-enoate and 12,13-bis(methylthio)octadec-9-enoate. The cleavage between the methylthio-substituted carbons yielded sets of key fragment ions showing the original double-bond positions in the starting ester. Standard experiments using other authentic methyl dienoates revealed the accuracy of this convenient method. The analysis of [2,2- 2H 2]linoleic acid and naturally-occurring dienoic fatty acids using this method is also described.

Trialkylphosphine-carbon disulfide adducts as eight-electron bridging ligands. X-ray structures of dimanganese complex [Mn2(CO)6(.mu.-S2CPCy3)] and [Mn2(CO)4(.mu.-S2CPCy3)(.mu.-dppm)

Trialkylphosphine-carbon disulfide adducts as eight-electron bridging ligands. X-ray structures of dimanganese complex [Mn2(CO)6(.mu.-S2CPCy3)] and [Mn2(CO)4(.mu.-S2CPCy3)(.mu.-dppm)

Determination of Double-Bond Positions in Highly Unsaturated Fatty Acids by GC-MS

A method for determining double-bond positions in highly unsaturated fatty acids by GC-MS was developed and is conducted as follows : A highly unsaturated fatty acid methyl ester is partially reduced with hydrazine or deuterated hydrazine. After acidification, the resulting mixture containing several kinds of unsaturated esters along with one saturated ester is recovered by hexane extraction and then separated by argentation TLC according to the number of double bonds. The isolated methyl monoenoate fraction corresponding to standard methyl cis-monoenoates is subjected to I2-catalyzed reaction with dimethyl disulfide. The resulting dimethyl disulfide adducts of methyl monoenoates areanalyzed by GC-MS. The cleavage between the methylthio-substituted carbons yielded sets of key fragment ions showing the original double-bond positions in the monoenoate carbon chain. The GC-MS data on the structures of methyl monoenoates derived from the starting highly unsaturated ester confirmed the original double-bond positions in the molecule of the starting ester. Separately using hydrazine and deuterated hydrazine as reducing reagents for the simultaneous analysis of the same sample provided further useful data for identifying the sample structure owing to the resulting shift of key fragment ions with deuterium atoms.This method was applied to the analysis of polyenoic fatty acids in eel total lipid. The most highly unsaturated fatty acid in the lipids was found to be cis-4, cis-7, cis-10, cis-13, cis-16, cis-19-docosahexaenoic acid based on mass spectral data.

ChemInform Abstract: Non‐Metal Derivatives of the Bulkiest Known Tertiary Phosphine, Trimesitylphosphine.

Abstract Trimesitylphosphine (Pmes3) is the bulkiest known tertiary phosphine. The low yield synthesis of this known compound, its failure to form a carbon disulfide adduct or a selenide derivative, the relatively low values for v(P—O), v(P—S) and v(P—H) in its oxide, sulfide and phosphonium salt respectively, and the high barriers to rotation about the P—Cipso bond in Pmes3, and its derivatives all attest to this fact. Nevertheless, Pmes3, does show chemistry typical of most tertiary phosphines due to its relatively high basicity and the electronic character of even this most bulky phosphine must also be considered in any discussion of its chemistry.

Phosphorylase and creatine kinase modification by thiol-disulfide exchange and by xanthine oxidase-initiated S-thiolation

The reaction of glycogen phosphorylase b and creatine kinase with glutathione disulfide, cystine, and cystamine was compared by direct analysis on electrofocusing gels. This method was useful for individual proteins or for mixtures of the proteins. Millimolar concentrations of glutathione disulfide were required for both proteins and the rate of modification of each protein was similar. The reaction of glutathione disulfide with creatine kinase was inhibited by reduced glutathione (GSH), but the effect on the reaction with phosphorylase was minimal. Cystine and cystamine were required in micromolar amounts to effectively form the disulfide adducts. Both proteins were modified by cystine but cystamine reacted only with phosphorylase. Cystamine (10 μ m) was an effective inhibitor of the reaction of phosphorylase b with 2 m m glutathione disulfide. S-thiolation of creatine kinase inactivated the enzyme and a direct assay of the enzyme activity could be used to quantitate S-thiolation of this protein by each of the disulfides. The effect of each disulfide on enzyme activity confirmed the results obtained by gel electrofocusing. Glutathione disulfide and cystine both inactivated the enzyme while cystamine had no effect on the activity. S-thiolation of phosphorylase had no observable effect on any activity parameter, but it effectively prevented binding of phosphorylase to high-molecular-weight glycogen, probably at the glycogen storage site of phosphorylase. The rate of S-thiolation of a mixture of phosphorylase and creatine kinase by thiol-disulfide exchange with glutathione disulfide was compared to the rate of S-thiolation of these proteins by a xanthine oxidase-initiated process (presumably due to protein sulfhydryl activation by reactive oxygen species). The xanthine oxidase-initiated mechanism was somewhat faster than thiol-disulfide exchange with both proteins. It was shown that GSH inhibited S-thiolation of creatine kinase by this mechanism as well as by thiol-disulfide exchange. It is suggested that both mechanisms may play a role in protein S-thiolation in vivo. For proteins that are typified by creatine kinase, the concentration of GSH in the cells may determine whether the S-thiolated form of the protein accumulates. For proteins typified by phosphorylase b, the accumulation of S-thiolated forms may be more independent of GSH.

Non-Metal Derivatives of the Bulkiest Known Tertiary Phosphine, Trimesitylphosphine

Abstract Trimesitylphosphine (Pmes3) is the bulkiest known tertiary phosphine. The low yield synthesis of this known compound, its failure to form a carbon disulfide adduct or a selenide derivative, the relatively low values for v(P—O), v(P—S) and v(P—H) in its oxide, sulfide and phosphonium salt respectively, and the high barriers to rotation about the P—Cipso bond in Pmes3, and its derivatives all attest to this fact. Nevertheless, Pmes3, does show chemistry typical of most tertiary phosphines due to its relatively high basicity and the electronic character of even this most bulky phosphine must also be considered in any discussion of its chemistry.

ChemInform Abstract: A Novel Synthesis of Oxazoline‐Azetidinone Derivatives.

AbstractThe reaction of the Fuji disulfide adducts (I) with P(O‐Et)3 in refluxing dry benzene gives the desired products of type (II) together with co‐products of type (III), as is shown for (Ia), (Ib).

Cis‐Vaccenic acid in pulp lipids of commonly available fruits

AbstractFatty acids of commonly available fruit pulps have been analyzed by capillary gas chromatography of their methyl esters and by gas chromatography‐mass spectrometry as their dimethyl disulfide adducts. The gas chromatographic and mass spectrometric data proved that these fruits always containedcis‐vaccenic (cis‐11‐octadecenoic) acid as a component fatty acid of their pulp lipids. The concentration ofcis‐vaccenic acid in total octadecenoic acids ranged from 1.9% to 95.1% in the fruit pulps examined. The highest concentration of this acid was detected in pulp lipids of Japanese persimmon (Diospyros kaki). In fruit pulp lipids,cis‐vaccenic acid was a common octadecenoic acid as well as oleic acid.

Sabulodes caberata guen�e (Lepidoptera: Geometridae)

A 6,9-nonadecadiene, (Z)-9-nonadecene, andn-nonadecane were identified in extracts of sex pheromone glands of femaleSabulodes caberata Guenée. Potential pheromonal activity of gland components was assessed by electroantennogram measurements of gas-chromatographic fractions of abdominal tip extracts. Chemical identification was based on gas chromatography and mass spectrometry of parent compounds, hydrogenation products, ozonolysis products, dimethyl disulfide adducts, and synthesis. The monoene was synthesized via coupling of alkyl and acetylenic intermediates. (Z,Z)-6,9-Nonadecadiene (Z6,Z9-19∶H) was synthesized from methyl linoleate via chain lengthening. SyntheticZ6,Z9-19∶H had the same retention times on polar and nonpolar capillary gas-chromatographic columns as the 6,9-nonadecadiene from the sex pheromone glands. In field testsZ6,Z9-19:H alone produced trap catch of maleS. caberata and addition of (Z)-9-nonadecene orn-nonadecane had no effect on trap catch.

Formation of mixed disulfide adducts at cysteine-281 of the lactose repressor protein affects operator and inducer binding parameters.

The lactose repressor protein has been modified with three sulfhydryl-specific reagents which form mixed disulfide adducts. Methyl methanethiosulfonate (MMTS) and 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) completely reacted with all three cysteine residues, whereas only partial reaction was observed with didansylcystine. Cysteines-107 and -140 reacted stoichiometrically with MMTS and DTNB, while Cys-281 was modified only at higher molar ratios. Didansylcystine reacted primarily with cysteines-107 and -140. Affinity of MMTS-modified repressor for 40 base pair operator DNA was decreased 30-fold compared to unmodified repressor, and this decrease correlated with modification of cysteine-281. DTNB-modified repressor bound operator DNA with a 50-fold weaker affinity than unmodified repressor. Modification of the lac repressor with didanylcystine decreased operator binding only 4-fold, and nonspecific DNA binding increased 3-fold compared to unmodified repressor. No change in the inducer equilibrium binding constant was observed following modification with any of these reagents. In contrast, inducer association and dissociation rate constants were decreased approximately 50-fold for repressor completely modified with MMTS or DTNB, while didansylcystine had minimal effect on inducer binding kinetics. Correlation between modification of Cys-281 and the observed decrease in rate constants indicates that this region of the protein regulates the accessibility of the sugar binding site. The parallel between the increase in the Kd for repressor binding to operator, the altered rate constant for inducer binding, and modification of cysteine-281 suggests that this region of the protein is crucially involved in the function of the repressor protein.

SYNTHESIS OF SOME CARBONYL DERIVATIVES OF TRIS(AMINOMETHYL)PHOSPIE OXIDE

Abstract Miscellaneous phosphohrylated carbamates, ureas and thioureas of potential value as flame retardants for cotton have been synthesized from a key intermediate, tris(aminomethyl)phosphine oxide (1), whose synthesis we recently described. Reactions were carried out between 1 and representative chloroformates, isocyanates, thiocyanates and ureas, and with carbonyl sulfide and carbon disulfide. An improved procedure was developed for the thermal cyclization of the carbonyl sulfide and carbon disulfide adducts.

Double-bond location in monounsaturated fatty acids by dimethyl disulfide derivatization and mass spectrometry: Application to analysis of fatty acids in pheromone glands of four lepidoptera

A rapid analytical procedure for the determination of the position of double bonds in mixtures of monounsaturated fatty acid methyl esters has been developed. The method is based on direct capillary GC-MS-EI analysis of dimethyl disulfide adducts. The procedure was applied to mixtures of monounsaturated fatty esters from pheromone gland extracts of three tortricids from theChoristoneura genus,C. fumiferana, C. occidentalis, andC. pinus pinus, and one noctuid from the Plusiinae subfamily,Plusia chalcites. A correlation was found between the known major pheromone components in the four species with the corresponding fatty acids. Some of the additional fatty acids may be precursors to as yet unidentified minor pheromone components, present in extremely small quantities, in these species.

Cis-Vaccenic Acid in Plant Lipids. II.

A rapid and highly specific method for the determination of cis-vaccenic acid content in plant lipids by mass chromatography has been developed.Two calibration curves were obtained from the mass chromatography of several standard mixtures containing known amounts of dimethyl disulfide adduct (DMDSA) of methyl cis-vaccenate and DMDSA of methyl oleate. The content of cis-vaccenic acid in standard mixtures was proportional to the values calculated from the peak areas of characteristic ions due to the fragmentation of DMDSA of these esters.A mixture of fatty acid methyl esters prepared from plant total lipids was subjected to a reaction with dimethyl disulfide in the presence of I2 as the catalyst for 30min. After removal of contaminating by-products from the reaction products by thin-layer chromatography, the purified DMDSA fraction of methyl monoenoates was introduced into a gas chromatograph-mass spectrometer.This method has been found applicable to the determination of cis-vaccenic acid content in naturally-occurring lipids, such as chlorella, parsley seed, soybean, and maturing Mallotus japonicus seed lipids.

Determination of double bond position in mono-unsaturated acetates by mass spectrometry of dimethyl disulfide adducts

Determination of double bond position in mono-unsaturated acetates by mass spectrometry of dimethyl disulfide adducts

Reactivity of the triethylphosphine-carbon disulfide adduct (Et3P.CS2) toward cobalt(II) cations in the presence of the tris (tertiary phosphines) triphos and etriphos. X-ray crystal structure of the complex [(etriphos)Co(S2C(H)PEt3)](BPh4)2

Die l : 1:1-molare Umsetzung von [Co(OH2)6 ](BF4)2 mit Et3P.CS2 und 1,1,1-Tris-[diphenylphosphinomethyH-ethan fuhrt abhangig von den Reaktionsbe- dingungen zu unterschiedlichen Produkten.

Reactivity of the triethylphosphinecarbon disulfide adduct Et 3PCS 2 toward iron(II) cations in the presence of the bis(tertiary phosphines), depe, and diphos, x-ray crystal structures of the complexes [(depe) 2Fe(S 2CPEt 3)](BPh 4) 2 and [(depe) 2Fe(S 2CH)](BPh 4)

Reaction of the triethylphosphinecarbon disulfide adduct Et 3PCS 2 with iron(II) aquocations in the presence of the bis(tertiary phosphines) depe or diphos, and NaBPh 4 has given the monomeric complexes [(depe) 2Fe(S 2CPEt 3)](BPh 4) 2, 1, and [(diphos)Fe(S 2CPEt 3) 2](BPh 4) 2 · 0.5 (CH 3) 2CO, 3 (depe = 1,2-bis(diethylphosphino)ethane; diphos = 1,2-bis(diphenylphosphino)ethane). Compound 1 undergoes nucleophilic attack by hydride ion on the coordinated Et 3PCS 2 ligand to give the dithioformato derivative [(depe) 2Fe(S 2CH)](BPh 4), 2. The structures of compounds 1 and 2 have been determined from counter diffraction X-ray data. Crystal data for 1 are: triclinic, space group P 1 , a 18.583(8), b 14.836(7), c 14.019(7) », α 94.38(4), β 102.56(4), γ 103.34(4)°, Z = 2, R = 0.080. Crystal data for 2 are: monoclinic, space group P2 1/ a, a 28.912(10), b 11.949(6), c 13.386(7) », β 94.35(5)°, Z = 4, R = 0.076. In both structures the iron atom displays a distorted octahedral geometry, being linked to the phosphorus atoms of two depe molecules and to the two sulfur atoms of the zwitterion in compound 1 or of the dithioformato group in compound 2.

Reactivity of the triethylphosphine-carbon disulfide adduct toward metal carbonyls. X-ray structures of the complexes [Cr(CO)5(S2CPEt3)] and [Mo(CO)2(PEt3)(.mu.-S2CPEt3)

Reactivity of the triethylphosphine-carbon disulfide adduct toward metal carbonyls. X-ray structures of the complexes [Cr(CO)5(S2CPEt3)] and [Mo(CO)2(PEt3)(.mu.-S2CPEt3)

Herstellung und Reaktionen der valenzpolaromeren Verbindung (4,4‐Dimethyl‐2‐thiazolin‐5‐dimethyliminium)‐2‐thiolat ⇌ (1‐Dimethylthiocarbamoyl‐1‐methyl‐äthyl)‐isothiocyanat aus 3‐Dimethyl‐amino‐2,2‐dimethyl‐2H‐azirin und Schwefelkohlenstoff

Synthesis and reactions of the valence polaromeric compound (4,4‐dimethyl‐2‐thiazoline‐5‐dimethyliminium)‐2‐thiolate ⇌ 1‐dimethylthiocarbamoyl‐1‐methyl‐ethyl isothiocyanate from 3‐dimethylamino‐2,2‐dimethyl‐2H‐azirine and carbon disulfide.3‐Dimethylamino‐2,2‐dimethyl‐2H‐azirine (1) reacts with carbon disulfide to give crystals which have the dipolar structure 3a [(4,4‐dimethyl‐2‐thiazoline‐5‐dimethyliminium)‐2‐thiolate, Scheme 1]. In solution, the non‐dipolar (charge‐free) isomeric form 3b (1‐Dimethyl‐thiocarbamoyl‐1‐methyl‐ethyl isothiocyanate) is almost exclusively populated. Reaction products are derived from both forms: Derivatives of 3a are the hydrolysis product 6, the sodium borohydride reduction product 7 and the methylation products 9 and 10, respectively (Scheme 2). The isothiocyanate form 3b is responsible for the various reaction products with amines (Scheme 3). One of the reaction products with ammonia, namely 20, is also obtained by the reaction of 1 with thiocyanic acid.Thermolysis of the azirine/carbon disulfide adduct 3 leads to 2‐dimethylamino‐4,4‐dimethyl‐2‐thiazoline‐5‐thione (17) in high yield. A possible mechanism is outlined in Scheme 4. The same compound is also formed by rearrangement of 3 under the catalytic influence of dimethylamine. Its structure has been established by X‐ray crystallography (section 4). Again a rearrangement is involved in the reductive (NaBH4) conversion of 17 to 7, the direct reduction product of the dipolar species 3a (Scheme 5).The isothiocyanate form 3b is able to react with a second molecule of 3‐dimethylamino‐2,2‐dimethyl‐2H‐azirine (1) to yield compound 25, which in the crystalline or dissolved state appears to be almost entirely populated by the carbodiimide form with structure 25b (Scheme 7), though all reaction products of 25 (reduction with sodium borohydride, addition of water or hydrogen sulfide, Schemes 7 and 8) are derived from the dipolar form 25a, not detectable as such; here again therefore there is a dynamic equilibrium 25a ⇌ 25b.The two forms of adduct 3, namely 3a and 3b, are obviously very easily interconverted at room temperature and therefore can be considered as valence polaromeric forms (section 5). A classification of the dipolar (zwitterionic) form is given, which allows a comparison of various dipolar species and gives as indication of charge stabilization by delocalization.The versatile reactivity of the 3‐dimethylamino‐2,2‐dimethyl‐2H‐azirine/carbon disulfide adduct is demonstrated by the fact that with simple reagents approximately 25 derivatives have been obtained, most of them being new heterocyclic compounds.