Zur Umsetzung des Zweikomponentensystems Triethylphosphit/Tetrachlorkohlenstoff mit wasserstoffhaltigen Nucleophilen 1. Die Reaktion mit Säureamiden

Reaction of the Two-component System Triethylphosphite/Carbon Tetrachloride with Nucleophiles Containing Hydrogen. 1. Reaction with Acyl Amides Acyl amides react with the two-component system triethylphosphite/carbon tetrachloride yielding N-acyl phosphazenes, (EtO)₃P?N? Ac. In this way (EtO)₃P?N? P(O)(OEt)₂, (EtO)₃P?N? CN, (EtO)₃P?N? C(O)Ph, and (EtO)₃P?N? SO₂Ph were prepared. Ethyl esters of phosphoric acid and trichloromethane phosphonic acid were obtained as by-products.     

Zur Umsetzung des Zweikomponentensystems Trialkylphosphit/ Tetrachlorkohlenstoff mit wasserstoffhaltigen Nucleophilen 2. Die Reaktion mit Ammoniak und Aminen

Reaction of the Two-component System Trialkylphosphite/Carbon Tetrachloride with Nucleophiles Containing Hydrogen. 2. Reaction with Ammonia and Amines Ammonia and primary amines react with the two-component system trialkylphosphite/carbon tetrachloride yielding diester-amides of phosphoric acid, (RO)₂P(O)NHR′. If an excess of amine is used compounds of the type ROP(O)(NHR′)₂ and OP(NHR′)₃ are formed too. By the reaction of (RO)₃P/CCl₄ in presence of secondary and tertiary amines the first reaction product is (RO)₂P(O)CCl₃ which yields with the amine [NRR′R″R″′]⁺[Cl₃CP(OR)O₂]^?; (R = Et, Bu).     

Identification of two aromatic isomers between 3- and 4-hydroxy benzoic acid by their perturbation on the potential oscillations of a Belousov-Zhabotinsky system

A novel method for identification of two aromatic isomers of mono hydroxy benzoic acid (HBA) was reported by using their different perturbation effects on the potential oscillations of a Belousov-Zhabotinsky (BZ) system. In such a system, a macrocyclic complex of Cu [CuL](ClO₄)₂ was used as catalyst in which ligand L is 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene. To the BZ system, 3-hydroxy benzoic acid (3-HBA) could temporarily quench and regenerate potential oscillations with damping characters after inhibition time (t_in) while 4-hydroxy benzoic acid (4-HBA) could only change the oscillation amplitude (ΔA) to give damping oscillations with no inhibition time. Thus, these two isomers of HBA were identified. Reaction mechanisms of BZ have been proposed by FKN model. An explanation of perturbation mechanism is that, although 3-HBA reacted with BrO₂ while 4-HBA reacted with BrO₃⁻, they all produced 1,4-quinone.     

A simple, convenient method for the synthesis of maleic anhydrides from α-keto esters and alkanoic acid anhydrides using the TiCl4/n-Bu3N reagent system

Reaction of α-keto esters with alkanoic acid anhydrides using the TiCl₄/n-Bu₃N reagent system gives the corresponding maleic anhydrides in 62-95% yields.     

Palladium-catalyzed reaction of methyl 5-amino-4-chloro-2-methylthiopyrrolo[2,3-<Emphasis Type="Italic">d</Emphasis>]-pyrimidine-6-carboxylate with arylboronic acids. Synthesis of 1,3,4,6-tetraazadibenzo[<Emphasis Type="Italic">cd,f</Emphasis>]-azulene heterocyclic system

Densely substituted methyl 5-amino-4-aryl-7-methyl-2-methylthio-7H-pyrrolo[2,3-d]pyrimidine-6-carboxy- lates were synthesized by the palladium-catalyzed cross-coupling reaction of methyl 5-amino-4-chloro-7-methyl-2-methylthio-7H-pyrrolo[2,3-d]pyrimidine-6-carboxylate with arylboronic acids using Pd(OAc)₂/dicyclohexyl(2-biphenyl)phosphine/K₃PO₄ as a catalyst system. Reaction of methyl 5-amino-4-chloro-7-methyl-2-methylthio-7H-pyrrolo[2,3-d]pyrimidine-6-carboxylate with 2-formylphenyl- boronic acid led to a novel heterocyclic system – 1,3,4,6-tetraazadibenzo[cd,f]azulene.     

ZnCl2 and CuCl promoted aldol reactions of isocyanoacetate with α,β-unsaturated carbonyl compounds

Reaction of ethyl isocyanoacetate with α,β-unsaturated carbonyl compounds was promoted by a stoichiometric amount of ZnCl₂ or a catalytic amount of CuCl/Et₃N (1:1) to give 5-alkenyl-4-carboethoxyoxazolines (3) in moderate yields. The oxazolines (3) were converted by palladium catalyst to 2-formamino-2,4-alkadienoic acid ethyl esters (5).     

Co(II) halide complexes with 2-amino-3-methylpyridinium and 2-amino-5-methylpyridinium: synthesis,crystal structures,and magnetic properties

Reaction of CoX₂ · nH₂O with either 2-amino-3-methylpyridine (3-MAP) or 2-amino-5-methylpyridine (5-MAP) in aqueous acid gave complexes, (3-MAPH)₂CoX₄ or (5-MAPH)₂CoX₄ (H₂O) _n [n = 0,1; X = Cl, Br; 3-MAPH = 2-amino-3-methylpyridinium, 5-MAPH = 2-amino-5-methylpyridinium]. The 3-MAPH salts are formed in the triclinic crystal system while the 5-MAPH salts are formed in the monoclinic crystal system. Three of these compounds exhibit weak antiferromagnetic interactions along with varying degrees of single-ion anisotropy, however, 1 shows easy-plane anisotropy and exhibits a mixture of ferromagnetic and antiferromagnetic interactions.     

A NEW EFFICIENT SYNTHESIS OF TRIFLUOROACETYL HALIDES AND MIXED ANHYDRIDES OF PHOSPHORUS AND TRIFLUOROACETIC ACIDS

Abstract

Reaction of trifluoroacetic anhydride with chloroanhydrides of phosphorus acids R₂P(O)CI results in formation of mixed anhydrides R₂P(O) OCOCF₃ and trifluoroacetic acid halides CF₃COX (X=Cl, Br, I) in quantitative yield.     

One-pot reaction of 2-formylbenzoates,hexamethyldisilazane, and diethyl phosphite in the presence of Yb(OTf)3: Synthesis of 3-phosphonate phthalides

Reaction of 2-formylbenzoates with hexamethyldisilazane and diethyl phosphite in the presence of Yb(OTf)₃ proceeded smoothly at room temperature to afford addition adducts, which were readily cyclized to 3-phosphonate phthalides by adding trifluoroacetic acid (TFA). The reactions employing Sc(OTf)₃ instead of Yb(OTf)₃ produced 3-phosphonate isoindolinones without addition of TFA.     

Über Chalkogenolate. 160. Umsetzung von 1,2-Ethandithiolaten mit Kohlenstoffdisulfid 2. 1,2-Ethan-bis(trithiokohlensäure) und Alkylester der Säure

On Chalcogenolates. 160. Reaction of 1,2-Ethanedithiolates with Carbon Disulfide. 2. 1,2-Ethane-bis(trithiocarbonic acid) and Alkyl Esters of This Acid The reaction of potassium 1,2-ethane-bis(trithiocarbonate) with hydrochloric acid at 0°C gives unstable, deep yellow coloured 1,2-ethane-bis(trithiocarbonic acid) The 1,2-ethane-bis(alkyl trithiocarbonates) RS? CS? SCH₂CH₂S? CS? SR, where R = CH₃ and C₂H₅, have been formed by reaction of potassium 1,2-ethane-bis(trithiocarbonate) with the corresponding alkyl iodide. The called compounds have been characterized by means of diverse spectroscopic methods.     

Synthesis and reactions of the transition metal substituted tin hydride HSn[Mo(CO)3C5H5]3

Reaction of HMo(CO)₃C₅H₅ and Sn(C₅H₅)₂ produces the tin hydride HSn[Mo(CO)₃C₅H₅]₃ (I). Reaction of I with CCl₄, CHCl₃, or CH₂Cl₂ gives ClSn[Mo(CO)₃C₅H₅]₃ (II). With hydrogen chloride the hydride I reacts to produce the dichloride Cl₂Sn[Mo(CO)₃C₅H₅]₂. The first step in this reaction is cleavage of the SnH bond to produce the chloride II. The hydride I reacts with acetic acid to produce the diacetate (CH₃COO)₂Sn[Mo(CO)₃C₅H₅]₂.     

A Hydrogen‐Bonded Framework Complex without Lattice Solvents: Synthesis Reversible Crystal‐to‐Amorphous Transformation and Chromic Properties

Reaction of Ni(NO₃)₂·6H₂O with H₄BPTC (H₄BPTC = Biphenyl‐3,3′,4,4′‐tetracarboxylic acid) produced a 3D hydrogen‐bonded framework complex 1 , not containing lattice solvents, with empirical formula [Ni(H₂O)₆]·H₂BPTC. The complex exhibits an interesting reversible crystal‐to‐amorphous transformation property unaccompanied by lattice solvents release/loading and shows selective and reversible chromic response to methanol.     

SYNTHESIS OF SOME NEW 3-ARYLOXYMETHYL- 4-PHENYL-5-(N-SUBSTITUTED CARBOXAMIDOMETHYLTHI0)-S-TRIAZOLES

Abstract

3-Aryloxymethyl-4-phenyl-5-mercapto-s-triazoles (I_a-c) have been synthesized and reacted with N-chloroacetyl derivatives of aromatic and/or heterocyclic amines to yield 5-(N-aryl/heterocyclyl)-carboxamidomethyl thio-s-triazole derivatives 2_a-o and 3_a-o respectively. Reaction of I_a-u with ethyl chloroacetate gave the corresponding esters 4_a-c which were reacted with hydrazine hydrate to give hydrazides 5_a-c. Condensation of 5_a-c with aromatic aldehydes gave Schiff s bases 6_a-u with on cycloaddition reaction with thioglycolic acid yielded 4-thiazolidinones 7_a-g. Some of these compounds were screened in vitro for their antibacterial activities.     

Bis[N,N′‐diisopropylbenzamidinato(−)]silicon(II): Lewis Acid/Base Reactions with Triorganylboranes

Reaction of the donor‐stabilized silylene 1 (which is three‐coordinate in the solid state and four‐coordinate in solution) with BEt₃ and BPh₃ leads to the formation of the Lewis acid/base complexes 2 and 3 , respectively, which are the first five‐coordinate silicon compounds with an Si?B bond. These compounds were structurally characterized by crystal structure analyses and by multinuclear NMR spectroscopic studies in the solid state and in solution. Additionally, the bonding situation in 2 and 3 was analyzed by quantum chemical studies.     

Lewis and Brönsted acid catalyzed Friedel-Crafts hydroxyalkylation of mucohalic acids: a facile synthesis of functionalized γ-aryl γ-butenolides

A catalytic, green and practical method for Friedel-Crafts hydroxyalkylation of mucohalic acid has been accomplished. Reaction of mucohalic acids with various electron-rich aromatic compounds in the presence of catalytic (1 mol % to 10 mol %) In(OTf)₃ or Brönsted acid, such as H₂SO₄ in acetic acid provides γ-aryl γ-butenolides in moderate to excellent yield.     

Reactions of 3-(polyfluoroacyl)chromones with hydroxylamine: synthesis of novel R-containing isoxazole and chromone derivatives

Reaction of 3-(polyfluoroacyl)chromones with hydroxylamine free base proceeds via nucleophilic 1,4-addition followed by opening of the pyrone ring and subsequent cyclization to 4-(polyfluoroalkyl)-4H-chromeno[3,4-d]isoxazol-4-ols in good yields. On treatment with trifluoroacetic acid, the isoxazole ring of this annulated heterocyclic system opens to give 3-cyano-2-(polyfluoroalkyl)chromones, which were successfully hydrolyzed with concentrated H₂SO₄ to afford 3-carbamoyl-2-(polyfluoroalkyl)chromones. On the other hand, oximation of 3-(polyfluoroacyl)chromones with hydroxylamine hydrochloride occurs either at the carbonyl carbon atom connected to the R^F group or at the C-2 atom to give 3-R^FC(NOH)-chromones and 5-R^F-4-salicyloylisoxazole oximes, respectively. The former were easily converted to 3-R^F-4-salicyloylisoxazoles by simple heating in dimethyl sulfoxide.     

Functional group analysis of Suwannee River fulvic acid with reactive fluorescent probes

The reactive functional group content of Suwannee River fulvic acid (SRFA) was determined by reaction with fluorescent probes. Reaction with a triflate (R-SO₂CF₃) provided the total reactive group content in SRFA, and pyrene butanoic acid was used to determine the hydroxyl and amino groups. After purification of the product, standard addition analysis was used for quantification. The total reactive site content of SRFA was found to be 13.9 mmol/g, of which 57% were carboxylic acids, and 43% hydroxyl and amino groups. These values compare well with those obtained by other methods.     

Synthetic,structural, spectroscopic and solution speciation studies of the binary Al(III)–quinic acid system. Relevance of soluble Al(III)–hydroxycarboxylate species to molecular toxicity

Efforts to delineate the interactions of Al(III), a known metallotoxin, with low molecular mass physiological substrates involved in cellular processes led to the investigation of the structural speciation of the binary Al(III)–quinic acid system. Reaction of Al(NO₃)₃ · 9H₂O with d-(−)-quinic acid at a specific pH (4.0) afforded a colorless crystalline material K[Al(C₇H₁₁O₆)₃] · (OH) · 4H₂O (1). Complex 1 was characterized by elemental analysis, FT-IR, DSC–TGA, ¹³C-MAS NMR, solution ¹H and ¹³C NMR, and X-ray crystallography. The structure of 1 reveals a mononuclear octahedral complex of Al(III) with three singly ionized quinate ligands bound to it. The three ligand alcoholic side chains do not participate in metal binding and dangle away from the complex. The concurrent study of the aqueous speciation of the binary Al(III)–quinic acid system projects a number of species complementing the synthetic studies on the binary system Al(III)–quinic acid. The structural and spectroscopic data of 1 in the solid state and in solution emphasize its physicochemical properties emanating from the projections of the aqueous structural speciation scheme of the Al(III)–quinic acid system. The employed pH-specific synthetic work (a) exemplifies essential structural and chemical attributes of soluble aqueous species, arising from biologically relevant interactions of Al(III) with natural α-hydroxycarboxylate substrates, and (b) provides a potential linkage to the chemical reactivity of Al(III) toward O-containing molecular targets influencing physiological processes and/or toxicity events.     

Umsetzung von Arsolanen,Arsenanen und Arsepinen mit Oximen

Reaction of Arsolanes, Arsenanes, and Arsepines with Oximes The reaction of methyl-substituted arsolanes, arsenanes and arsepines with oximes results in it opening of the cyclic arsinous acid esters. In the course of the reaction of the substituted arsolanes (CH₂)₂O₂As? X[X = N(CH₃)₂, OCH₃, Cl] and (CH₂)₂ON(CH₃)As? N(CH₃)₂ with oximes the group X is substituted by the oxime; an opening of the rings does not take place.     

A kinetic study of electron transfer from L-Ascorbic acid to sodium perborate and potassium peroxy disulphate in aqueous acid and micellar media

Kinetics of oxidation of L-ascorbic acid (H₂A) by sodium perborate (SPB) and peroxy disulphate (PDS) have been investigated in aqueous acid and micellar media. Reaction kinetics indicated first-order dependence on both |oxidant| and |H₂A|. Increase in ionic strength (μ) increased reaction rate only in H₂SO₄ media. Rate of SPB oxidation of H₂A has been accelerated by acidity in HNO₃ and HCl media while a decreasing trend is observed in HClO₄ and H₂SO₄ media. The results are interpreted by various theories of acidity functions. Reaction rate is enhanced by the addition of added |H₂O₂| indicating a H₂O₂ coordinated boron species to be active in the present system. In the absence of micelle, increase in |acid| altered the PDS(SINGLEBOND)H₂A reaction rate marginally (a very small positive effect with HClO₄ and negative effect with H₂SO₄). Most plausible mechanisms have been proposed on the basis of experimental results. Activation parameters evaluated for specific kinetic constants are in accord with outer sphere electron transfer mechanism. In SPB(SINGLEBOND)H₂A system, addition of anionic micelle (Sodium lauryl sulfate) increased the rate, stabilizing the cationic species in the transition state in all the acid media. Although rate of PDS oxidation of H₂A was catalyzed by TX and inhibited by SDS at critical micellar concentration (CMC) increase in |acid| (both HClO₄ and H₂SO₄) beyond 9.6 × 10⁻⁴ M decreased the rate of oxidation. This trend was explained due to the repulsive interaction of coanion, HA⁻, and negatively charged micellar species. © 1996 John Wiley & Sons, Inc.