Triphenylstibine oxide–phosphorus(V) sulfide as a novel condensation catalyst system: application to the synthesis of dipeptides

Triphenylstibine oxide (Ph₃SbO) and phosphorus(V) sulfide (P₄S₁₀) synergistically catalyzed the aminolysis of N-protected amino-acids with amino-acid esters in benzene. Ph₃SbO accelerated both the initial conversion of carboxylic moieties into the corresponding thiocarboxylic moieties by P₄S₁₀ and the subsequent aminolysis of the resulting thiocarboxylic acids. Thus, dipeptides such as Z–A–A′–OEt (where Z = PhCH₂OC(O)– and A,A′ = Ala,Gly; Gly,Gly; Leu,Gly; Phe,Gly; Phe,Leu;Ser,Gly; Val,Gly, respectively) were conveniently prepared even at 35°C.     

Synthesis and Characterisation of Two Examples of Unsymmetrically Disubstituted Cyclotetrathiazenes, 1,5-(X)(Y)S4N4[X = Ph3PN- and Y = i) (p-CH3C6H4) Ph2PN- and ii) (P-CH3C6H4)2PhPN-]

Abstract

1,5- [(p-tolyl)diphenylphosphinimino] (triphenylphosphinimino)tetrasulphurtetranitride, (I) and 1,5-[di(p-tolyl)phenylphosphinimino] (triphenylphosphinimino)tetrasulphurtetranitride, (II) are the first examples of heterodisubstituted tetrasulphurtetranitride derivatives to be made. Their synthesis and structural characterization are described.     

Total synthesis of (3R, 4S)-4-hydroxylasiodiplodin

Abstract

An alternative and concise total synthesis of (3?R, 4S)-4-Hydroxylasiodiplodin has been reported from inexpensive and commercially available 6-heptenal and Orsellinic acid starting materials. The key steps involved in the synthesis are Wittig reaction, Sharpless epoxidation, Yamaguchi esterification and ring-closing metathesis (RCM).     

Azidokomplexe von Vanadium(IV) und Vanadium(V): (Ph4P)2[VOCl2(μ‐N3)]2 und (Ph4P)2[VOCl(μ‐N3)(N3)2]2

Azido Complexes of Vanadium(IV) and Vanadium(V): (Ph₄P)₂[VOCl₂(μ‐N₃)]₂ and (Ph₄P)₂[VOCl(μ‐N₃)(N₃)₂]₂ (Ph₄P)₂[VOCl₂(μ‐N₃)]₂ ( 1 ) was prepared by reaction of (Ph₄P)[VO₂Cl₂] with trimethylsilylazide in the molar ratio 1:2 in dichloromethane solution to give dark green, moisture sensitive, non‐explosive single crystals. The reaction is accompanied by the formation of the dark blue side‐product (Ph₄P)₂[VOCl(μ‐N₃)(N₃)₂]₂ ( 2a ), which can be obtained as the main product by application of a large excess of Me₃SiN₃. Dark blue needles of 2a crystallize spontaneously from the CH₂Cl₂ solution within one hour at 4 °C. After standing at 4 °C under its mother liquid within 24 hours a first‐order phase transition of 2a occurs forming dark blue prismatic single crystals of 2b . According to single crystal X‐ray structure determinations, 2a and 2b crystallize in the same type of space group , however, with different lattice dimensions. The vanadium(IV) complex 1 is characterized by X‐ray structure determination and by vibrational spectroscopy (IR, Raman) as well as by EPR spectroscopy, whereas 2b is characterized by IR spectroscopy. 1 : Space group P2₁/n, Z = 2, a = 1009.5(1), b = 1226.6(2), c = 1943.0(2) pm, β = 98.42(1)°, R₁ = 0.0672. The complex anion forms centrosymmetric units with V₂N₂‐four‐membered rings with a V···V distance of 335.6(1) pm and coordination number five on the vanadium(IV) atoms. 2a : Space group , Z = 1, a = 1089.0(2), b = 1097.1(2), c = 1310.1(2) pm, α = 92.99(1)°, β = 106.12(2)°, γ = 117.05(2)°, V = 1309.8(4) ų, d_calc. = 1.440 g·cm^?3, R₁ = 0.0384. The complex anion forms centrosymmetric units of symmetry C_i with V₂N₂ four‐membered rings and VN bond lengths of 200.4(3) and 234.4(2) pm, respectively. The non‐bonding V···V distance amounts to 356.2(1) pm. 2b : Space group , Z = 1, a = 1037.3(2), b = 1157.6(2), c = 1177.2(2) pm, α = 98.48(2)°, ° = 103.82(2)°, γ = 106.33(2)°, V = 1281.8(4) ų, d_calc. = 1.471 g·cm^?3, R₁ = 0.0724. The structure of the complex anion is similar to the anion of 2a with VN bond lengths of the four‐membered V₂N₂ ring of 203.3(4) and 235.2(4) pm, respectively, and a non‐bonding V···V distance of 357.5(1) pm.     

Facile synthesis of 1-(arylimino)naphthalen-2(1H)-ones from anilines and 2-naphthols promoted by NaBr/K2S2O8/CAN

An efficient method has been developed for the synthesis of 1-(arylimino)naphthalen-2(1H)-ones through the cascade reaction of anilines and 2-naphthols promoted by NaBr/K₂S₂O₈/Ce(NH₄)₂(NO₃)₆. Using this protocol, a series of 1-(arylimino)naphthalen-2(1H)-ones was obtained in good to excellent yields (17 examples, 70–92% yields). The reactions may proceed through the following steps: bromination of 2-naphthols by in-situ-generated bromine from NaBr and K₂S₂O₈ to afford 1-bromonaphthalen-2-ols, coupling of 1-bromonaphthalen-2-ols with anilines to afford the corresponding amines, and subsequent oxidation of the amines into the products by Ce(NH₄)₂(NO₃)_6. These newly obtained α-imine ketones have great potentials for synthesis of special optical materials bearing naphthalene moiety.     

Stabilization of tautomeric forms P(OH)3 and HP(OH)2 and their derivatives by coordination to palladium and nickel atoms in heterometallic clusters with the Mo3MQ44+ core (M = Ni, Pd; Q = S, Se)

The cluster aqua complexes [Mo₃(MCl)Q₄(H₂O)₉]³⁺ (M = Pd or Ni) in hydrochloric acid solutions induce isomerization of the hydrophosphoryl compounds (HO)₂P(O)H, (HO)P(O)H₂, PhP(O)(OH)H, and Ph₂P(O)H into the hydroxo tautomers P(OH)₃, HP(OH)₂, PhP(OH)₂, and Ph₂P(OH), which are stabilized by coordination of the phosphorus atom to the Pd or Ni atoms. The reactions were studied by ³¹P NMR and UV-Vis spectroscopy. The kinetics of the reactions of phosphorous acid with [Mo₃(PdCl)Q₄(H₂O)₉]³⁺ was investigated by spectrophotometry. The [Mo₃(Pd(PhP(OH)₂))S₄(H₂O)₂Cl₇]³⁻ complex was isolated as a supramolecular adduct with cucurbit [8]uril, and the [Mo₃(Ni(P(OH)₃))S₄(H₂O)₈Cl]³⁺ complex was isolated as an adduct with cucurbit [6]uril. The structures of both compounds were established by X-ray diffraction analysis.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 606–613, March, 2005.     

亚砜还原法合成聚苯醚硫醚的结构与性能研究

以氟苯和氯化亚砜反应合成了4,4’-二氟二苯亚砜,并将其与4,4’二羟基二苯硫醚在N-甲基吡咯烷酮溶剂中进行亲核取代反应合成了聚苯醚硫醚醚亚砜,用乙二酰氯/四丁基碘化铵还原该亚砜聚合物制备了聚苯醚硫醚。用红外光谱和核磁共振谱对合成单体的结构进行了确认,同时对聚合物进行了红外光谱、核磁共振、元素分析、X射线光电子能谱、X射线衍射、DSC分析、TG/DTG以及溶解性测试。结果表明聚苯醚硫醚样品具有氧醚和硫醚交替的线性结构,特性粘度为0.55 dL/g的PPSE熔点达236℃,在氮气条件下,样品起始分解温度和最大分解速率处温度分别为359℃和514℃,在700℃时的重量保留率为43.3%,且在加热条件下能溶解于N-甲基吡咯烷酮(NMP)、二甲基乙酰胺(DMAc)、二甲基甲酰胺(DMF)等极性有机溶剂中。     

A first methodical approach to salts with unsymmetrical fluorophenyl(pentafluorophenyl)difluoroiodonium(V) cations [Rf(RF)IF2] (Rf=x-FC6H4, x=2, 3, 4; RF=C6F5)

A promising approach to the unknown type of [Ar′(Ar)IF₂]X salts is offered. x-FC₆H₄IF₄ (x=2, 3, 4) reacts with C₆F₅BF₂ in CH₂Cl₂ and forms [x-FC₆H₄(C₆F₅)IF₂][BF₄] salts in good yields. For [4-FC₆H₄(C₆F₅)IF₂][BF₄] the fluoro-oxidizer property is shown in reactions with weakly reducing agents like E(C₆F₅)₃ (E=P, As, Sb, Bi) and ArI (Ar=4-FC₆H₄, C₆F₅). The fluorine/aryl substitution method is also applied to the synthesis of [(4-FC₆H₄)₂IF₂][BF₄], an example with two identical aryl groups in the difluoroiodonium(V) moiety.     

Bis(silylaminodiarylphosphoranylsilylmethyl-C,N)-tin(II) and -lead(II) complexes and their precursors; structures of H(LL′), H(LL″), Sn(LL″)2 and Pb(LL″)2; [LL′] = [CH(SiMe3)P(Ph)2NSiMe3],

We report a series (a)-(d) of tandem reactions involving the conversion of: (a) 2CH₂(SiMe₃)P(Ph)₂NSiMe₃ [2H(LL′)] (III) into successively [Li(LL′)]₂ (1a) and [Pb(LL′)₂] (3a); (b) 1a in turn into {[Li(LL″)]₂} (2) and [Pb(LL″)₂] (4); (c) 1a successively into Sn(LL′)Cl (5) and [Sn(LL″)₂] (6); (d) (1b) into (3b). Experimental details for the preparation and characterisation (including elemental analysis and multinuclear NMR spectra in C₆D₆ and EI mass spectra) of 1a, 2, 3a, 3b, 4, 6, III (a new synthesis) and IV are provided. The X-ray structures of crystalline 4, 6, III and IV are presented; those of 1a, 2 and 3a were previously published.     

Synthese und Kristallstruktur von Na10[P4(NH)6N4](NH2)6(NH3)0,5 mit dem adamantanartig aufgebauten Anion [P4(NH)6N4]4−

Synthesis and Crystal Structure of Na₁₀[P₄(NH)₆N₄](NH₂)₆(NH₃)_0.5 with an Adamantane-like Anion [P₄(NH)₆N₄]^4? Crystals of Na₁₀[P₄(NH)₆N₄](NH₂)₆(NH₃)_0.5 were obtained by the reaction of P₃N₅ with NaNH₂ (molar ratio 1:20) within 5 d at 600°C in autoclaves. The following data characterize X-ray investigations: Fm3 m, Z = 8, a = 15.423(2) Å, Z(F) = 261 with F ≥ 3 σ(F) Z(Variables) = 27, R/R_w = 0.086/0.089 The compound contains the hitherto unknown anion [P₄(NH)₆N₄]^4?, which resembles adamantane. The total structure can be described as follows: The centers of gravity of units of [Na₈(NH₂)₆(NH₃)]²⁺ – 8Na⁺ on the corners of a cube, 6NH₂^? on the ones of an inscribed octahedron with NH₃ in the center – follow the motif of a cubic-closest packed arrangement. Units of [Na₁₂(NH₂)₆]⁶⁺ – 12Na⁺ on the corners of a cuboctahedron and 6NH₂^? on the ones of an inscribed octahedron – occupy all octahedral and those of [P₄(NH)₆N₄]^4? all tetrahedral sites.     

Synthese und Struktur von [(Me2PhP)3Cl2ReN]2ReCl4, [(Me2PhP)3Cl2ReN]2ReCl4 · 2 SbCl3 und [Re(NH)Cl2(PMe2Ph)3][SbCl6]

Synthesis and Structure of [(Me₂PhP)₃Cl₂ReN]₂ReCl₄, [(Me₂PhP)₃Cl₂ReN]₂ReCl₄ · 2 SbCl₃ and [Re(NH)Cl₂(PMe₂Ph)₃][SbCl₆] The reaction of ReNCl₂(PMePh)₃ with SbCl₅ in toluene yields the trinuclear complex [(Me₂PhP)₃Cl₂Re≡N]₂ReCl₄ · 2 SbCl₃ ( 1 · 2 SbCl₃). It forms triclinic crystals with the composition 1 · 2 SbCl₃, as well as monoclinic crystals 1 · 2 SbCl₃ · 4 C₇H₈. The monoclinic crystals with the space group P2₁/c, and a = 1212.3(2), b = 2098.5(4), c = 1827.7(3) pm, β = 95.51(1)°, Z = 2, have been used for a crystal structure determination. In the centrosymmetric complex 1 two complexes ReNCl₂(PMe₂Ph)₃ coordinate with their nitrido ligands a square planar, central unit ReCl₄. The SbCl₃ molecules are coordinated by chlorine bridges to Cl atoms of 1 , and, in addition, connect the complexes 1 with each other. The SbCl₃ free compound 1 is obtained in good yield by the reaction of ReNCl₂(PMePh)₃ with ReCl₄(NCEt)₂. It crystallizes in the triclinic space group P1 with a = 1037.7(3), b = 1153.0(2), c = 1393.8(3) pm, α = 72.31(2)°, β = 74.06(2)°, γ = 67.94(2)°, and Z = 1. The bond lengths of the Re–N triple bonds are 172 pm in 1 and 170 pm in 1 · 2 SbCl₃. By the reaction of ReNCl₂(PMePh)₃ with SbCl₅ in CH₂Cl₂ the solvent is decomposed forming HCl which protonates the nitrido ligand to afford the imido complex [Re(NH)Cl₂(PMe₂Ph)₃][SbCl₆] ( 2 ) crystallizing in the monoclinic space group P2₁/n with a = 1221.4(2), b = 1358.6(2), c = 2177.3(1) pm, β = 92,72(1)° and Z = 4. The Re–N distance in the almost linear unit Re≡N–H is 169,1 pm.     

Facile Yb(OTf)3 promoted one-pot synthesis of polyhydroquinoline derivatives through Hantzsch reaction

Yb(OTf)₃ catalyzed efficient Hantzsch reaction via four-component coupling reactions of aldehydes, dimedone, ethyl acetoacetate and ammonium acetate at ambient temperature was described as the preparation of polyhydroquinoline derivatives. The process presented here is operationally simple, environmentally benign and has excellent yield. Furthermore, the catalyst can be recovered conveniently and reused efficiently.     

Effect of temperature and water as additive on the MW and thermal properties of copoly(p-phenylene/biphenylene sulfide)s

Copoly(p-phenylene/biphenylene sulfide)s, PPBS were prepared from sodium sulfide trihydate(Na₂S·3H₂O), p-dichlorobenzene (DCB), and 4,4′-dibromobiphenyl (DBB) comonomers in N-methyl-2-pyrrolidinone (NMP) solvent using an autoclave. The molecular weights of PPBS copolymers were determined by high temperature (210°C) GPC in 1-chloronaphthalene solvent. The reaction temperature had little effect on the molecular weights of PPBS copolymers with water as additive at the level of 3 mol H₂O per 1 mol Na₂S. PPBS copolymer, however, showed maximum molecular weight of M_w = 24.1 × 10³ with the total water content of 9 mol H₂O per 1 mol Na₂S at an optimum polymerization temperature of 270°C. The resulting PPBS copolymer sample showed higher T_g (by 30°C) and lower T_m (by 10°C) than PPS homopolymer prepared under similar conditions. © 1996 John Wiley & Sons, Inc.     

Facile access to the pnictocenium ions [Cp*ECl]+ (E = P, As) and [(Cp*)2P]+: chloride ion affinity of Al(OR(F))3

The pnictocenium salts [Cp*PCl]⁺[μCl]^? ( 1 a ), [Cp*PCl]⁺[ClAl(OR^F)₃]^? ( 1 b ), [Cp*AsCl]⁺[ClAl(OR^F)₃]^? ( 2 ), and [(Cp*)₂P]⁺[μCl]^? ( 3 ), in which Cp*=Me₅C₅, μCl=(^FRO)₃Al? Cl? Al(OR^F)₃, and OR^F=OC(CF₃)₃, were prepared by halide abstraction from the respective halopnictines with the Lewis superacid PhF→Al(OR^F)₃. 1 The X‐ray crystal structures of 1 a , 2 , and 3 established that in the half as well as in the sandwich cations the Cp* rings are attached in an η²‐fashion. By using one or two equivalents of the Lewis acid, the two new weakly coordinating anions [μCl]^? and [ClAl(OR^F)₃]^? resulted. They also stabilize the highly reactive cations in PhF or 1,2‐F₂C₆H₄ solution at room temperature. The chloride ion affinities (CIAs) of a range of classical strong Lewis acids were also investigated. The calculations are based on a set of isodesmic BP86/SV(P) reactions and a non‐isodesmic reference reaction assessed at the G3MP2 level.     

A large series of isotypic Mo(V) diphosphates with a tunnel structure: From A(MoO)10(P2O7)8 with A=Ba, Sr, Ca, Cd, Pb to A(MoO)5(P2O7)4 with A=Ag, Li, Na, K

The single crystal structure of a series of nine isotypic Mo(V) diphosphates was determined from crystals with composition A²⁺(MoO)₁₀(P₂O₇)₈ (A=Ba, Sr, Ca, Cd, Pb) and A⁺(MoO)₅(P₂O₇)₄ (A=Ag, Li, Na, K). The structure of those phosphates, built up of corner sharing MoO₆ octahedra, MoO₅ tetragonal pyramids and P₂O₇ diphosphates groups, forms eight-sided tunnels as described by Lii et al. for A=Ag. New features are evidenced: (1) existence of two orientations, up and down along b for the MoO₅ pyramids; (2) maximum insertion rate of the divalent cations which is twice less than that of the univalent cations; (3) different behavior of the series “Pb, Sr, Ba, Li, Na, K” which exhibits only one kind of site for the inserted cation, compared to the “Cd, Ca, Ag” series for which two kinds of sites are observed; (4) off-centering of the A-site cations with respect to the tunnel axis; and (5) unusually high thermal factors along the tunnel axis, but absence of ionic conductivity.     

Catalytic Conversion of SO2 Released from the Roasting Process of Copper Sulfides to SO3 by New Nanocatalysts of Vanadium(V) Oxide

Two new silica‐supported vanadium(V) oxide nanocatalysts were synthesized from vanadyl(IV ) sulfate and vanadyl(IV ) oxalate by the sol–gel method. The nanocatalysts were characterized by Fourier transform infrared spectroscopy, thermogravimetry, X‐ray diffraction, X‐ray fluorescence, and field‐emission scanning electron microscopy. The average diameter of the nanocatalysts was ~16 nm. The catalytic activity of both nanocatalysts was investigated in the oxidation of sulfur dioxide (SO₂ ) released from the roasting of copper sulfides to sulfur trioxide (SO₃ ), and the results were compared with those obtained from a commercial BASF (Baden Aniline and Soda Factory) catalyst. It is worth mentioning that our nanocatalysts show higher activity than the commercial catalyst for the oxidation of SO₂ to SO₃ under similar reaction conditions. The suggested electrocatalytic mechanism for the oxidation of SO₂ to SO₃ was confirmed by computational studies. Our calculations indicate that the terminal VO bond of V₂O₅ is likely the most active site for the adsorption and oxidation of SO₂ .     

The Preparation and X-Ray Structure of [AsPh4][Ph2P(S)NSiMe3] · 0.5 THF

The reaction of Ph₂P(S)N(SiMe₃)₂ with potassium tert-butoxide in a 1:1 molar ratio produces K[Ph₂P(S)NSiMe₃], which was converted to the AsPh₄⁺ salt by metathesis with [AsPh₄]Cl. The X-ray crystal structure of [AsPh₄][Ph₂P(S)NSiMe₃] · 0.5 THF consists of noninteracting AsPh₄⁺ and Ph₂P(S)NSiMe₃^? ions with d(P? S) = 1.980(4) Å and d(P? N) = 1.555(8) Å. The PNSi bite angle in the anion is 136.3(5)°. Electrophilic attack by Ph₂P(S)Cl occurs at the sulfur atom of Ph₂P(S)NSiMe₃^?. The oxidation of the anion with iodine produces a disulfide which regenerates K[Ph₂P(S)NSiMe₂] upon treatment with potassium tert-butoxide.