One pot synthesis using supported reagents system KSCN/SiO2-RNH3OAc/Al2O3: synthesis of 2-aminothiazoles and N-allylthioureas

A simple and efficient method has been developed for the synthesis of 2-aminothiazoles and N-allylthioureas from commercially available materials in one pot by using a supported reagents system, KSCN/SiO₂-RNH₃OAc/Al₂O₃, in which α-halo ketone reacts first KSCN/SiO₂ and the product, α-thiocyanatoketone, reacts with RNH₃OAc/Al₂O₃ to give the final product, 2-aminothiazoles, in good yield and allyl bromide reacts with KSCN/SiO₂ and the product, allyl isothiocyanate, reacts with RNH₃OAc/Al₂O₃ to give N-allylthiourea.     

The reaction of hexafluoropropene oxide with alkyl lithium reagents

A series of alkyl lithium reagents has been found to react with hexafluoropropene oxide in the presence of ether to give carbinols of the type CF₃CFRCR₂OH. Butyllithium in hexane reacts “abnormally” to give the carbinol CF₃C(OH) BuCF₂Bu. Mechanisms to account for these difference are presented.     

One-pot synthesis of N-allylthioureas using supported reagents

A simple and efficient method has been developed for the synthesis of N-allylthioureas from allylic bromides in one-pot by using a supported reagents system, KSCN/SiO₂-RNH₃OAc/Al₂O₃, in which allyl bromide reacts first with KSCN/SiO₂ and the product, allyl isothiocyanate, reacts with RNH₃OAc/Al₂O₃ to give the final product, N-allylthiourea, in good yield.     

Effects of wavelength,pressure and scavengers on the isotopically selective multiphoton dissociation of C2F5Cl

The enrichment factor of carbon-13 in the products of multiphoton dissociation of C₂F₅Cl has been investigated as a function of CO₂-laser wavelength and fluence. Pressure effects have been studied both on the pure sample and in the presence of several additives (He, Xe, O₂, H₂, NO, I₂). Dissociation of ¹²C₂F₅Cl and enrichment in carbon-13 are strongly affected by O₂, which reacts with the fluoroalkyl radicals formed in the dissociation process.     

Synthesis and electrochemistry of a vanadium-pillared manganese oxide

A new manganese dioxide pillared by vanadium oxide species has been synthesized hydrothermally from permanganate. It has the electrochemically active MnO₂ layer structure, which has been extensively studied as a battery cathode. The vanadium oxide ions, together with the water molecules, reside in between the oxide sheets; dehydration occurs without structural change. The (VO_y)_0.1MnO₂·nH₂O has a rhombohedral structure, with hexagonal parameters a=2.843(6) Å, c=22.08(2) Å. It reacts readily with lithium with a capacity around 150 mAh g⁻¹; the pillar ions do not appear to impede reaction.     

Dimethylplatinum(IV) compounds. V. Preparation and reations of bis(salicylaldehydato) complexes

Two geometrical isomers of Pt(CH₃)₂(Sal)₂ have been prepared and identified by ¹H NMR spectra. Some reactions of isomer A (phenolic oxygen atoms trans to CH₃) and isomer B (aldehydic oxygen atoms trans to CH₃) are reported. Isomer B reacts with C₅D₅N to produce species containing unidentate Sal in solution, while isomer A tends to lose Sal with formation of hydroxo species. Primary amines react with isomer B to form salicylaldimine complexes. Isomer A reacts with en to form Pt(CH₃)₂en(0H)₂.     

One-pot synthesis of α-bromoesters and ketones from β-ketoesters and diketones using supported reagents system

A simple and efficient method has been developed for the synthesis of α-bromoesters and ketones from β-ketoesters and diketones in one pot using a supported reagents system, CuBr₂/Al₂O₃-Na₂CO₃/Al₂O₃, in which β-ketoester reacts first with CuBr₂/Al₂O₃ and the product, α-bromo-β-ketoester, reacts with Na₂CO₃/Al₂O₃ to give the final product, α-bromoesters in good yields.     

Recherches sur la formation et la transformation des esters LXXXI [1]. Sur la réaction d'isothiocyanates avec l'acide hydrazinoéthylphosphorique,et de l'isocyanate de phényle avec l'acide colaminephosphoreux

Hydrazinoethyl phosphoric monoester has been prepared by reacting hydrazinoethanol with polyphosphoric acid, and isolated as di-sodium salt. Sodium hydrazinoethyl phosphate reacts with phenylisothiocyanate (in H₂O+ethanol) to yield mainly the derivative thiocarbamoylated at the substituted nitrogen atom. This derivative, heated for one night at 100° in 0.5 N HCl, is cyclized to 3-amino-2-phenylimino-thiazolidine in 62% yield. Sodium hydrazinoethyl phosphate reacts with o-methoxycarbonylphenyl isothiocyanate (in H₂O+dioxane) at the unsubstituted nitrogen atom to yield mainly the corresponding quinazoline derivative (IV, X = OPO₃Na₂). This derivative, heated for one night at 100° in 0.5 N HCl, is cyclized to 2-o-carboxyphenylamino-dihydro-δ²-1, 3, 4-thiadiazine (Va) in 55% yield (hydrolysis of the lactamic function as well). Aminoethyl phosphorous monoester (colaminephosphorous acid) reacted with phenylisocyanate (in H₂0+dioxane) in slightly alkaline medium (one equivalent of NaOH) yields sodium N-phenylcarbamoylaminoethyl phosphite. Refluxed for 20 minutes in 1N NaOH, this carbamoyl derivative is not cyclized but only hydrolyzed to the open-chained N-phenyl-N′-hydroxyethylurea (VII).     

Synthesis and Structure Characterization of 2‐(Dimethylaminomethyl)pyrrolate and 2,5‐Bis(dimethylaminomethyl)pyrrolate Zirconium Complexes

Tetrakis(diethylamido)zirconium reacts with 2‐(dimethylamino)methyl pyrrole (DMAMP) and 2,5‐[bis(dimethylamino)methyl]pyrrole (BDMAMP) to give Zr(NEt)₂(DMAMP)₂ 1 and Zr(NEt)₃(BDMAMP) 2 , respectively. Both 1 and 2 have been characterized by ¹H and ¹³C NMR spectroscopies and 1 has also been characterized by X‐ray crystallography. Complex 1 shows an agostic interaction between Zr and H(21A) in solid state that is not sustained in solution. Reacting 1 with 2 equivalents of trimethylsilyl chloride in toluene yields ZrCl₂(DMAMP)₂ 3 in 75% yield which was characterized by ¹H and ¹³C NMR spectroscopies.     

Three Roles for the Fluoride Ion in Palladium‐Catalyzed Hiyama Reactions: Transmetalation of [ArPdFL2] by Ar′Si(OR)3

From the kinetic data on the transmetalation/reductive elimination in fluoride‐promoted Hiyama reactions, obtained using electrochemical techniques, it has been established that fluoride ions play three roles. F^? reacts with trans‐[ArPdBrL₂] (L=PPh₃) to form trans‐[ArPdFL₂], which reacts with Ar′Si(OMe)₃ in the rate‐determining transmetalation, whereas trans‐[ArPdBrL₂] does not react with Ar′Si(OMe)₃. F^? reacts with Ar′Si(OMe)₃ to deliver the unreactive silicate Ar′SiF(OMe)₃^?, thus leading to two antagonistic kinetic effects. In addition, F^? catalyzes the reductive elimination from intermediate trans‐[ArPdAr′L₂].     

Kinetic study of surface reactions of O2 and H2 on polycrystalline copper

Adsorption and transformation of O₂, H₂, water and methanol on polycrystalline copper in the 300–400 K range have been studied by surface potential variations. In particular, O₂ reacts with H(a) to form OH(a) with a first order kinetic law, whereas OH(a) reacts with H₂ to form water which desorbs and restores H(a) with an Elovich kinetic law.     

Reactions of homobinuclear platinum and palladium complexes with carbon monoxide

The reactivity of homobimetallic complexes of platinum(II) and palladium(II) containing diethyl(diphenylphosphinomethyl)amine (ddpa = (C₆H₅)₂PCH₂N(C₂H₅)₂) as a bridging ligand has been investigated. Carbon monoxide reacts reversibly with these complexes. The species formed are binuclear carbonyl-bridged derivatives, which can isomerize to ionic terminal carbonyl complexes. Reaction of [PtCl₂(CO)]₂[(C₂H₅)₄N]₂ with ddpa in dichloromethane gives the ionic platinum(I) complex [Pt(ddpa)Cl₂]₂[(C₂H₅)₄N]₂, which reacts with carbon monoxide. Still, homobimetallic derivatives of palladium(I) are unstable, and none have been isolated.     

Hydrothermal synthesis and electrochemistry of a manganese vanadium oxide, γ-MnV2O5

A new manganese vanadium oxide MnV₂O₅ has been synthesized using a mild hydrothermal reaction. MnV₂O₅ crystallizes in the orthorhombic system, space group Pnma, a=9.7585(2) Å, b=3.5825(1) Å, c=11.2653(2) Å. It is isostructural to γ-LiV₂O₅. It reacts readily and reversibly with lithium, with a stable capacity but with a large polarization.     

The reactions of Ir(CO)Cl(PPh3)2 with HSnPh3

A reinvestigation of the reaction of Ir(CO)Cl(PPh₃)₂, 1 with HSnPh₃ has revealed that the oxidative-addition product Ir(CO)Cl(PPh₃)₂(H)(SnPh₃), 2 has the H and SnPh₃ ligands in cis-related coordination sites. Compound 2 reacts with a second equivalent of HSnPh₃ by a Cl for H ligand exchange to yield the new compound H₂Ir(CO)(SnPh₃)(PPh₃)₂, 3. Compound 3 contains two cis- related hydride ligands. Under an atmosphere of CO, 1 reacts with HSnPh₃ to replace the Cl ligand with SnPh₃ and one of the PPh₃ ligands with a CO ligand and also adds a second equivalent of CO to yield the 5-coordinate complex Ir(CO)₃(SnPh₃)(PPh₃), 4. Compound 4 reacts with HSnPh₃ by loss of CO and oxidative addition of the Sn-H bond to yield the 6-coordinate complex HIr(CO)₂(SnPh₃)₂(PPh₃), 5 that contains two trans-positioned SnPh₃ ligands.     

Reaktionen von Tetrachloroaurat mit verschiedenen Aminen

Reactions of Tetrachloroaurate with Various Amines . Tetrachloroaurate reacts with aminoalcohols (L) in aqueous solution to give the complexes [Au^IL₂][Au^IIICl₄]. With t-butylamine the complex AuCl₃(t-BuNH₂) has been obtained, whereas from the reaction of Na[AuCl₄] with n-butylamine the imine gold(I) complex ClAu(NH?CH(CH₂)₂Me) has been isolated.     

Carbon monoxide poisoning as a probe for the active site(s) of a nickel-based olefin oligomerization catalyst

The interaction of the olefin oligomerization catalyst system derived from [Ni(sacsac)(PBu₃)Cl] (sacsac = pentane-2,4-dithionate = dithioacetylacetonate) with carbon monoxide (CO) has been examined by a combination of ³¹P NMR and FTIR spectroscopy. The catalyst is rapidly and completely inhibited by CO; however, removal of the CO restores catalytic activity. A CO-adduct of the active catalyst has a characteristic CO stretching frequency of 2042 cm^?1, and δ³¹P 9.9 ppm. Carbon monoxide does not react with [Ni(sacsac)(PBu₃)Cl], but [Ni(sacsac)(PBu₃)(Cl)] reacts with any of Et₂AlCl, BuLi, Li[Et₃BH] or K[(s-Bu)₃BH] under an atmosphere of carbon monoxide in the presence or absence of olefin to produce [Ni(PBu₃)(CO)₃], which has been identified by FTIR and ³¹P NMR. [Ni(sacsac)(PBu₃)Cl] reacts completely with BuLi or K[(s-Bu)₃BH] to form catalytically inactive species which yield active catalysts on addition of Et₂AlCl.     

Palladium(II) and platinum(II) complexes of Schiff bases derived from 2,6-diacetylpyridine and S-methyldithiocarbazate and the X-ray crystal structure of the [Pd(mdapsme)Cl] complex

Condensation of 2,6-diacetylpyridine (dap) with S-methyldithiocarbazate (smdtc) in a 1:2 molar ratio yields a bicondensed pentadentate Schiff base (H₂dapsme) which reacts with K₂MCl₄ (M = Pd^II, Pt^II) giving stable complexes of empirical formula, [M(dapsme)] · 0.5Me₂CO. These complexes have been characterized by a variety of physico-chemical techniques. Condensation of dap with smdtc in a 1:1 molar ratio also yields the bicondensed Schiff base (H₂dapsme) as the major product, but a mono-condensed one-armed Schiff base (Hmdapsme) is also obtained as a minor product. The latter reacts with K₂PdCl₄ in an EtOH–H₂O mixture yielding a crystalline complex of empirical formula, [Pd(mdapsme)Cl], the crystal structure of which has been determined by X-ray diffraction. The complex has a distorted square-planar structure in which the ligand is coordinated to the palladium(II) ion as a uninegatively charged tridentate chelating agent via the pyridine nitrogen atom, the azomethine nitrogen atom and the thiolate sulfur atom; the oxygen atom of the acetyl group does not participate in coordination.     

Synthesis, spectroscopic characterization, X-ray structure and DFT calculations of rhenium(III) complex with bis(3,5-dimethylpyrazol-1-yl)methane

[ReCl₃(MeCN)(PPh₃)₂] reacts with bis(3,5-dimethypyrazol-1-yl)methane (bdmpzm) in acetone to give [ReCl₃(bdmpzm)(PPh₃)]. The compound has been studied by IR, UV–Vis spectroscopy and X-ray crystallography. The molecular orbital diagram of [ReCl₃(bdmpzm)(PPh₃)] has been calculated with the density functional theory (DFT) method.     

Accelerated methods of synthesis of phosphorus-containing dendrimers

In order to shorten the long and tedious synthesis of dendrimers, several improvements have been proposed. This paper is a review of the improved methods recently published concerning the synthesis of phosphorus-containing dendrimers. It describes first the synthesis of hyperbranched polymers and their comparison with real dendrimers obtained from the same monomer. Then, the influence of the modification of the core of dendrimers is shown. In a third part, the use of dendrons is illustrated by several examples; they allow for instance to built a generation 8 directly from a generation 3 dendrimer. The last part describes the use of branched monomers of types AB₂ and CD₂, in which A reacts only with D and B reacts only with C. These reactions do not need any protecting groups, and the only by-products are H₂O and N₂. Using these monomers, the 4th generation is obtained in only four steps, instead of 8 for classical methods. This method has been improved by using more branched monomers AB₅ and CD₅, built from the cyclotriphosphazene. In this case, a dendrimer having 750 end groups is obtained in only three steps. The A (NH₂), B (PPh₂), C (N₃) and D (CHO) functions are identical in all cases, and they allow a real “Lego” chemistry, as shown by the synthesis of CA₂ and DB₂ monomers, also used for the accelerated synthesis of dendrimers.     

Crystal,molecular and electronic structure of [ReCl2(η2-N2COPh–N′,O)(PPh3)2]

[ReO(OEt)Cl₂(PPh₃)₂] reacts with benzoylhydrazine in the presence of PPh₃ and hydrochloric acid to give [N-benzoylhydrazido(3-)-O,N′]dichlorobis(triphenylphosphine) rhenium(V). The complex has been studied by IR, UV-Vis spectroscopy and X-ray crystallography. The molecular orbital diagram has been calculated with density functional theory (DFT). The spin-allowed singlet-singlet electronic transitions of [ReCl₂(η²–N₂COPh–N′,O)(PPh₃)₂] have been calculated with the time-dependent DFT method, and the UV-Vis spectrum of the title compound has been discussed on this basis.