- Reactions of undecacarbonyltriferrate with α,β-unsaturated acyl halides. Decomposition of 3-RCH=CHCOOCFe3(CO)10>- to 2-RCH=CHFe2(CO)7 involving transfer of the acyl group from oxygen to iron
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2 (PPN=bis(triphenylphosphine)iminium) (1) reacts with α,β-unsaturated acyl halides in CH2Cl2 at 25 deg C during 15 min to give 3-RCH=CHCOOCFe3(CO)10> (2a, 2b) (2a: R=CH3, 2b: R=Ph), which slowly decomposes to give
- Ishihara, Atsushi,Mitsudo, Take-Aki,Watanabe, Yoshihisa
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- Nitrosopersulfide (SSNO-) is a unique cysteine polysulfidating agent with reduction-resistant bioactivity
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Aims: The aim of the present study was to investigate the biochemical properties of nitrosopersulfide (SSNO-), a key intermediate of the nitric oxide (NO)/sulfide cross talk. Results: We obtained corroborating evidence that SSNO- is indeed a major product of the reaction of S-nitrosothiols with hydrogen sulfide (H2S). It was found to be relatively stable (t1/2 *1 h at room temperature) in aqueous solution of physiological pH, stabilized by the presence of excess sulfide and resistant toward reduction by other thiols. Furthermore, we here show that SSNO- escapes the reducing power of the NADPH-driven biological reducing machineries, the thioredoxin and glutathione reductase systems. The slow decomposition of SSNO- produces inorganic polysulfide species, which effectively induce per/polysulfidation on glutathione or protein cysteine (Cys) residues. Our data also demonstrate that, in contrast to the transient activation by inorganic polysulfides, SSNO- induces long-term potentiation of TRPA1 (transient receptor potential ankyrin 1) channels, which may be due to its propensity to generate a slow flux of polysulfide in situ. Innovation: The characterized properties of SSNO- would seem to represent unique features in cell signaling by enabling sulfur and nitrogen trafficking within the reducing environment of the cytosol, with targeted release of both NO and polysulfide equivalents. Conclusion: SSNO- is a surprisingly stable bioactive product of the chemical interaction of S-nitrosothiol species and H2S that is resistant to reduction by the thioredoxin and glutathione systems. As well as generating NO, it releases inorganic polysulfides, enabling transfer of sulfane sulfur species to peptide/protein Cys residues. The sustained activation of TRPA1 channels by SSNO- is most likely linked to all these properties. Antioxid. Redox Signal. 33, 1277–1294.
- Bogdándi, Virág,Ditrói, Tamás,Bátai, István Zoárd,Sándor, Zoltán,Minnion, Magdalena,Vasas, Anita,Galambos, Klaudia,Buglyó, Péter,Pintér, Erika,Feelisch, Martin,Nagy, Péter
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- Probing the mechanism of the PCl5-initiated living cationic polymerization of the phosphoranimine Cl3P=NSiMe3 using model compound chemistry
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New insight into the mechanism of the ambient temperature PCl5-initiatedliving cationic chain growth polycondensation of the N-silylphosphorani mine Cl3P=NSiMe3 (1) to give poly(dichlorophosphazene), [N=PCl2]n,has been provided by studies of model compound chemistry. Investigations of the reactivity of Cl- salts ofthe proposed cationic intermediates [Cl3P=N=PCl3] + ([2] +) and [Cl3PdN-PCl2dNdPCl3] + ([6]+) toward Ph3P=NSiMe3 (3a) provided evidence that under the usual polymerization conditions that involve a high monomer to initiator ratio, propagation occurs at both chain ends. However, analogous studies of near stoichiometric processes suggested that propagation is faster at one chain end, particularly when the chains are short. In addition, experiments involving [Ph3P=N=PPh3][PCl6] ([9][PCl6]) and the N-silylphosphoranimines R3P-NSiMe 3 3a (R = Ph) and 3b (R = p-CF3C6H 4),showed that the [PCl6]- anion, which is formed in the early stages of the polymerization and has hitherto been assumed to be an innocent spectator counteranion, is actually reactive under the r eaction conditions and can initiate oligomerization and polymerization. Finally, the absence of reactions between phosphoranimines 3b or 1 with the Cl- salts of the cations [Ph3P=N-PCl2=N=PPh3]+ ([10a]+), [Ph3P=N-(PCl2=N) 2= PPh3]+ ([5]+), and [Ph3P=N-(PCl 2=N) 3-PPh3]+ ([8]+) with P-Cl bonds located internally but not at the chain ends have shown that chain branching reactions are unlikely to be significant during the polymerization. These results identify key factors that complicate the living PCl5-initiated chain growth polycondensation of 1 and potentially lead to a loss of control over molecular weight and broaden the molecular weight distributions, but also indicate that the polymer formed is essentially linear rather than branched.
- Blackstone, Vivienne,Lough, Alan J.,Murray, Martin,Manners, Ian
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experimental part
p. 3658 - 3667
(2009/09/24)
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- Efficient phosphorus catalysts for the halogen-exchange (Halex) reaction
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New families of monomeric to dendritic, and monocationic to multicationic (PNP) compounds have been prepared and tested as catalysts in halogen exchange (Halex) reactions. Some of them allow an increase in the efficiency of these reactions which are performed in some cases under the mildest conditions reported up to now.
- Lacour, Marie-Agnes,Zablocka, Maria,Duhayon, Carine,Majoral, Jean-Pierre,Taillefer, Marc
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supporting information; experimental part
p. 2677 - 2682
(2009/10/20)
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- Cyclic sulphur-nitrogen compounds and phosphorus reagents: Part XIII-Reactions of cyclic sulphur-nitrogen chlorides with Ph3P-influences of tetiary base, Et3N and the ring size of the cyclothiazyl chloride on the product formation
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Similar to the reactions with S4N3Cl and S3N3Cl3, triphenylphosphine reacts with five-membered cyclic sulphur-nitrogen chlorides namely, S3N2Cl and S3N2Cl2 to give triphenylphosphiniminium chloride, Ph3P=NH+2Cl- as the major product.Maximum yield (ca. 90percent) is obtained when triphenylphosphine is reacted with S3N2Cl in acetonitrile at room temperature in 2 : 1 molar ratio.Analogous reactions performed in presence of triethylamine afford two cyclothiazene products containing phosphinimino substituent.The ring size of the S - N chloride seems to determine the nature of phosphiniminocyclothiazenes formed.A rationalization of the results obtained has been attempted.
- Mohan, T.,Senthivel, P.,Rao, M. N. Sudheendra
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p. 961 - 966
(2007/10/03)
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- Synthese, Charakterisierung und Reaktivitaet heterodinuklearer Komplexe: (Fe-Rh) (L=CO, HP(t-Bu)2), (Co-Rh)
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(2) reacts with K and PPN to give the heterobinuclear complexes (5) and (4), respectively.Treatment of 5 with KH results in its
- Walther, B.,Boettcher, H.-C.,Scheer, M.,Fischer, G.,Fenske, D.,Suess-Fink, G.
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p. 307 - 321
(2007/10/02)
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- Thiolate, Thioether, and Thiol Derivatives of Iron(0) Carbonyls
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A new series of anionic complexes of iron tetracarbonyl monofunctionalized with the ligand ->,-> (R = Ph, Et, Me, H), have been synthesized and characterized.The compound was formed in the reaction of and PhSSPh.The -> anion was characterized by X-ray diffraction as its +> salt and found to be a typical trigonal-bipyramidal complex in which the phenylthiolate ligand occupies an axial position with a Fe-S bond distance of 2.332(5) Angstroem and Fe-S-C(Ph) = 111.3(6) deg.The salt crystallized inthe orthorhombic space group Pbc21, with a = 9.529(4) Angstroem, b = 21.493(9) Angstroem, c = 20.185(9) Angstroem, V = 4134(3) Angstroem3, and Z = 2.Other members of the series of complexes, ->, were best obtained by ligand exchange of -> and the labile thioether complex (PhSMe)Fe(CO)4.The latter was produced from the low-temperature alkylation of the ->.Protonation of the thiolates (R = Ph, Et, Me, H) ultimately leads to formation of H2 and Fe2(μ-SR)2(CO)6; however, the intermediate thiol, (RSH)Fe(CO)4, could be observed at -78 to -40 deg C for R = Et, Me.The PhSH and HSH derivatives were unstable even at -78 deg C.
- Liaw, Wen-Feng,Kim, Christine,Darensbourg, Marcetta Y.,Rheingold, Arnold L.
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p. 3591 - 3597
(2007/10/02)
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- Substitution Reactions toward 2-Nitrobenzyl Pseudohalides. The Crystal Structure of 2-Nitrobenzyl Tellurocyanate
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The reactions between 2-nitrobenzyl pseudohalides, 2-NO2-PhCH2XCN, and pseudohalide ions, NCX- (X = S, Se or Te) have been studied kinetically in acetonitrile at 25.0 deg C.The reactions proceed through nucleophilic attack at the methylene carbon atom, forming exclusively the exchange products.The average nucleophilicity order, NCTe- >> NCSe- > NCS-, and the average leaving group order, NCTe- >/= NCSe- >/= NCS-, lead to a carbon basicity order NCTe- > NCSe- >/= NCS-, which is confirmed with equilibrium studies.A crystal structure determination of 2-nitrobenzyl tellurocyanate at ca. 135 deg C has revealed that the TeCN group is syn-clinal (gauche) to the C(CH2)-C(Ar) bond with a torsion angle of -48.5(5) deg.The TeCC plane forms an angle of 103.4(5) deg with the phenyl ring plane.In this conformation the steric influence of the 2-NO2 group in substitution reactions at the methylene carbon atom will be negligible except for bulky nucleophiles.The tellurium atom forms two fairly strong intermolecular bonds to nitrogen atoms from neighbouring tellurocyanate groups, viz. 2.889(6) Angstroem trans to the cyano group and 3.382(6) Angstroem trans to the methylene group.In the crystalline state the compound may be considered both as a tellurium(II) complex and as an organic pseudohalide.No intermolecular tellurium-oxygen contacts could be observed.
- Grung, Knut Eric,Roemming, Christian,Songstad, Jon
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p. 518 - 526
(2007/10/02)
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