Thermolysis of 3-phenyl-5-arylamino-1,2,4-oxadiazole and thiadiazole derivatives

Thermal reactions of 3-phenyl-5-arylamino-1,2,4-oxadiazoles I and II were investigated. Neat heating at ca. 250°C for 6 hours afforded H₂O, benzonitrile, arylcyanamides, arylamines, azobenzene, benzimidazole derivatives, and 3,3′-diphenyl-5,5′-bis[1,2,4-oxadiazolyl]. Analogous results were obtained by the thermolysis of 3-phenyl-5-anilino-1,2,4-thiadiazole III at ca. 200°C for 2 hours. In addition to H₂S, NH₃, and HNCS, phenyl isothiocyanate and thiocarbanilide were obtained. Thermolysis of III in quinoline as a radical trap gave analogous resuLts but also 2-anilinoquinoline. A free-radical mechanism has been suggested to account for the identified products. © 1997 John Wiley & Sons, Inc.     

Kinetic resolution of 5-(hydroxymethyl)-3-phenyl-2-isoxazoline by using the ‘low-temperature method’ with porous ceramic-immobilized lipase

A significant enhancement of the enantioselectivity (E value = 249) in the lipase-catalyzed resolution of a primary alcohol, racemic 5-(hydroxymethyl)-3-phenyl-2-isoxazoline (±)-1, was obtained by using the ‘low-temperature method’ (−60 °C) with porous ceramic-immobilized lipase (Amano PS-C II) and vinyl acetate in acetone.     

Photochemistry of 3-aryl-2-isoxazoline1

3-Phenyl-2-isoxazoline (1) was irradiated to give 4-phenyl-2-oxazoline (3), β-aminoaldehyde (14) and benzonitrile from its π-π^* singlet excited state. Several related derivatives afforded similar photoproducts on irradiation. The quantum yields of the photoreactions were dependent on the magnitudes of the singlet energies of the 2-isoxazolines. p-Cyanophenyl-2-isoxazoline (1c) formed a one-to-one photoadduct (22) with benzene.     

5-Substituted 3-Nitro-1-vinyl-1,2,4-triazoles

A series of 5-substituted 3-nitro-1-vinyl-1,2,4-triazoles were synthesized by alkaline treatment of the corresponding 1-(2-haloethyl- or 2-nitroxyethyl)-3-nitro-1,2,4-triazoles and by transvinylation of NH acids of the same series with vinyl acetate. The scope of applicability of the transvinylation procedure was established with respect to the azole pK _a value. The vinylic double bond on the nitrogen was shown to be inactive toward both nucleophilic and electrophilic reagents, whereas the halogen atom in position 5 exhibits enhanced reactivity. The latter factor provides the possibility for versatile structural modification via nucleophilic replacement of the 5-halogen atom by various groups, including triazolate ion.     

Synthesis of pyrido[1,2-a]pyrimido[4,5-d]pyrimidin-5-ones. Cyclization reaction of 4-[(3-hydroxy-2-pyridyl)amino]-2-phenyl-5-pyrimidinecarboxylic acid with acetic anhydride

Treatment of 4-[(3-hydroxy-2-pyridyl)amino]-2-phenyl-5-pyrimidinecarboxylic acid (X) with acetic anhydride under refluxing conditions afforded 10-hydroxy-2-phenyl-5H-pyrido[1,2-a]-pyrimido[4,5-d]pyrimidin-5-one acetate (IX). The intermediate X was prepared from 4-chloro-2-phenyl-5-pyrimidinecarboxylic acid ethyl ester (V). The reaction of V with the sodium salt of 2-amino-3-hydroxypyridine at room temperature gave 4-(2-amino-3-pyridyloxy)-2-phenyl-5-pyrimidinecarboxylic acid ethyl ester (VI). Treatment of VI with a hot aqueous sodium hydroxide solution and subsequent acidification gave X. Involvement of 4-[(3-hydroxy-2-pyridyl)amino]-2-phenyl-5-pyrimidinecaroboxylic acid ethyl ester (VIII) (Smiles rearrangement product) as an intermediate in the above alkaline hydrolysis reaction of VI to X was demonstrated by the isolation of VIII and its subsequent conversion into X under alkaline hydrolysis conditions. Acetylation of VIII with acetic anhydride in pyridine solution gave 4-[(3-hydroxy-2-pyridyl)amino]-2-phenyl-5-pyrimidinecarboxylic acid ethyl ester acetate (XI), which afforded IX on fusion at 220°. This alternative synthesis of IX from XI supported the structural assignment of IX. Fusion of VI gave 10-hydroxy-2-phenyl-5H-pyrido[1,2-a]pyrimido]4,5-d]pyrimidin-5-one (VII). The latter was also obtained when VIII was fused at 210°. Acetylation of VII with acetic anhydride afforded IX.     

Cyanoacetylene and Its Derivatives: XXXIV. Nucleophilic Addition of Tetrazole to Cyanoacetylenes

Nucleophilic addition of tetrazole to 4-hydroxy-4-alkyl-2-alkynonitriles and to 3-phenyl-2-propynonitrile occurred regiospecifically and afforded E-, Z-4-hydroxy-4-methyl-3-tetrazolyl-2-alkenonitriles and 3-tetrazolyl-3-phenyl-2-propenonitrile [20–40°C, 13–50 h, 4–15 wt% MOH (M = Na, K), THF (or DMSO)] in up to 69% yield. The attempt to perform cyclization of the hydroxy-containing adducts into iminodihydrofurans (KOH, ethanol, 23-25°C) resulted in vinyl nucleophilic substitution of the tetrazole moiety by an ethoxy group.     

Experimental and theoretical DFT study of the reaction of 3-amino-1,2-diols with dichloromethane and paraformaldehyde

The reactions of 3-phenyl-3-methylamino-1,2-propanediol 1a and 3-[(tert-butyldimethylsilyl)oxy]-1-methylamino-1-phenyl-2-propanol 1b with (CH₂O)n and CH₂Cl₂ are appropriate procedures for the preparation of 1,3-oxazines or 1,3-oxazolidines under proper selection of kinetic or thermodynamic reaction conditions. The reaction of 1b with (CH₂O)n or CH₂Cl₂, affords the oxazolidine 2b under kinetic conditions and then this compound can be slowly converted into 5-[(tert-butyldimethylsilyl)oxy]-3-methyl-4-phenyl-3,4,5,6-tetrahydro-2H-1,3-oxazine 3b under thermodynamic control. The mechanism proposed for this transformation and the effect of polar solvents on the acceleration of the reaction has been studied theoretically (DFT level).     

Diastereoselective synthesis of novel 5-substituted morpholine-3-phosphonic acids: further exploitation of N-acyliminium intermediates

The first diastereoselective total synthesis of 5-substituted morpholine-3-phosphonic acids is reported. The principal feature of the synthesis is the introduction of a dimethyl phosphonate group into 5-substituted morpholin-3-ones. The procedure is based on the preparation of N-Boc-(S)-5-phenyl- and N-Boc-(S)-5-benzylmorpholin-3-one from l-phenylglycine and l-phenylalanine methyl esters, followed by the formation of the 3-methoxylated compounds and subsequent reaction with trimethyl phosphite in the presence of BF₃·OEt₂. Diastereoselectivity in the formation of cis-disubstituted products is in agreement with the nucleophilic addition to other methoxylated derivatives.     

Transformation of benzonitrile into benzyl alcohol and benzoate esters in supercritical alcohols

The reactions of benzonitrile in supercritical methanol, ethanol, and 2-propanol were investigated under non-catalytic conditions. In supercritical methanol, benzonitrile was converted to methyl benzoate in high yield. The esterification reaction also occurred in supercritical ethanol to afford ethyl benzoate in moderate yield. The esterification could occur via a route analogous to the Pinner reaction. On the other hand, benzonitrile in supercritical 2-propanol yielded no ester. Benzyl alcohol was the major product in supercritical 2-propanol. We investigated the reaction of the CN bond in supercritical 2-propanol. In supercritical 2-propanol, N-benzylideneaniline was transferred to the reduction product (N-benzylaniline) and hydrolysis products (benzyl alcohol and aniline). The hydrolysis reaction was restricted when the reaction was carried out in supercritical 2-propanol with a low water content. This indicates that the water in the 2-propanol acts as a reagent for the hydrolysis of the CN bond. These results suggested the following reaction process: C₆H₅CN→C₆H₅CHNH→C₆H₅CHO→C₆H₅CH₂OH.     

2－氯／2－甲磺酰基－5－（2－苯基－4－喹啉基）－1，3，4－噁二唑化合物的合成及其亲核取代的研究

借处理２－羟基－５－（２－苯基－４－喹啉基）－１，３，二唑同ＰＣｌ＿５／ＰＯＣｌ＿３之间的反应合成了２－氯－５－（２－苯基－４－喹啉基）－１，３，４－二唑（３）和通过２－基－５－（２－苯基－４－喹啉基）－１，３，４－二唑的甲基化，然后氧化制得２－甲磺酰基－５－（２－苯基－４－喹啉基）－１，３，４－二唑（６）．并分别研究了３和６同胺、叠氮及肼的反应，得到２，５－二取代的二唑新衍生物．初步观察了部分化合物的抗菌活性．     

Investigations in the isoxazole series. 39. The protonation of 3-phenyl-2-oxazolines

An unusually powerful influence of substituents in position 5 on the basicity of 3-phenyl-2-isoxazolines has been shown by a spectrophotometric method. The ¹³C NMR spectra of 3-phenyl-2-isoxazoline, of its meta-nitro derivative, and of model compounds have been studied, and on this basis it has been concluded that protonation takes place at the nitrogen hetero atom.For communication 38 see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 609–611, May, 1985.     

Molecular structure,orbital structure,and relative stability of conformational isomers of 2-phenyl-5-trifluoroacetylpyrrole and its 1-vinyl derivative,according to data obtained by MNDO and MINDO/3 methods

According to quantum-chemical calculations and IR spectra, the molecule of 1-vinyl-2-phenyl-5-trifluoroacetylpyrrole has two spectroscopically different rotational isomers. Both forms are characterized by a practically orthogonal position of the phenyl substituent and a substantially nonplanar position of the vinyl and trifluoroacetyl substituent s relative to the central pyrrole fragment. The unsubstituted 2-phenyl-5-trifluoroacetylpyrrole exists primarily in a single form with a planar position of the trifluoroacetyl substituent and an orthogonal position of the phenyl substituent.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1785–1792, August, 1990.     

On the mechanism of photolysis of 4-phenyl-1,3,2-oxathiazolylio-5-oxide in ethanol : Evidence for ketene intermediates

Photolysis of 4-phenyl-1,3,2-oxathiazolylio-5-oxide (1) in ethanol in the presence of oxygen leads to benzonitrile (21%) and ethyl phenylglyoxylate (65%). Photolysis under an atmopshere of ¹⁵NO results in isotope exchange which is considered strong evidence for phenyl(nitrosothio)ketene (2) being in photolytic equilibrium with the starting material. In ethanolic solution saturated with nitric oxide the photolytic equilibrium is shifted towards the starting material resulting in formation of benzonitrile in 100% yield. Benzonitrile is formed by a competitive reaction route via benzonitrile sulfide.¹ Compound 2 does not undergo ethanolysis to ethyl(nitrosothio)phenylacetate (3). Ethyl phenylglyoxylate is probably formed via thiyl radical 6 resulting from homolytic scission of the SNO bond in ketene 2. Singlet molecular oxygen is present during photolysis of 1 but seems to be unimportant to the course of reaction.     

Phosphonium Ylides Stabilized with Cyano Group and 5-Acylamino-4-phenyl-2-thiazolyl Residue

Available ylide reagent Ph₃P = C(CN)C(S)NH₂ readily enters cyclocondensation with N-(chlorophenacyl)benzamide and its analogs. By this route were prepared new stabilized phosphonium ylides containing cyano group and the corresponding 5-acylamino-4-phenyl-2-thiazolyl fragment. All these compounds even under standard conditions are dephosphorylated under the action of hydrogen chloride in acetic acid to form 5-acylamino-4-phenyl-2-cyanomethylthiazoles in high yields. Their structure was proved by spectroscopic studies and independent synthesis.     

Solvent extraction of alkaline earth metals,and lithium with 1-phenyl-3-methyl-4-acylpyrazol-5-ones and trioctylphosphine oxide

The synergic extraction of magnesium, calcium, strongium, barium and lithium into cyclohexane or benzene containing 1-phenyl-3-methyl-4-acyl-pyrazol-5-one (HA) and tri-n-octylphosphine oxide (TOPO) was investigated as a function of pH, HA and TOPO concentration. The extracted species when the 4-benzoyl compound was used, were MA₂(TOPO)₂ (M = Mg, Ca, Sr), BaA₂(TOPO)₃ and LiA(TOPO)₂. When the 4-trifluoro-acetyl derivatives was used, the extracted species were the same except for SrA₂(TOPO)₃. Extraction constants for the synergic extractions were calculated.     

Reaction of 5-oxo-2-phenyl-4,4-bis(trifluoromethyl)-4,5-dihydro-1,3,2-benzodioxaphosphepine with chloral. The synthesis and spatial structure of 5-carbaphosphatrane containing a four-membered ring

Phosphorylation of 2-hydroxyphenyl 2,2,2-trifluoro-1-hydroxy-1-(trifluoromethyl)ethyl ketone with dichloro(phenyl)phosphine gave 5-oxo-2-phenyl-4,4-bis(trifluoromethyl)-4,5-di-hydro-1,3,2-benzodioxaphosphepine. Heating of the latter initiated an intramolecular interaction of the P atom with the carbonyl group. Hydrolysis of the intermediate product yielded 3-hydroxy-2-oxo-2-phenyl-3-[2,2,2-trifluoro-1-hydroxy-1-(trifluoromethyl)ethyl]-2,3-di-hydro-1,2λ⁵-benzo[d]oxaphosphole. The reaction was highly stereoselective (P_RC_S/P_SC_R). The reaction of the starting phosphepine with chloral proceeded highly stereoselectively (P_RC_SC_S/P_SC_RC_R) to give a 5-carbaphosphatrane derivative containing a four-membered ring, namely, 1-phenyl-3-trichloromethyl-10,10-bis(trifluoromethyl)-6,7-benzo-2,4,8,9-tetraoxa-1λ⁵-phosphatricyclo[3.3.2.0¹,⁵]decene. The trigonal bipyramid of the 5-carbaphosphatrane derivative is made up of the equatorial O atoms and the apical C atoms.     

Reaction of 3-phenyl-3-aminoquinoline-2,4-diones with isothiocyanates. Facile access to novel spiro-linked 2-thioxoimidazolidine-oxindoles and imidazoline-2-thiones

3-Phenyl-3-amino-1H,3H-quinoline-2,4-diones (1) react with alkyl or aryl isothiocyanates to give novel 9b-hydroxy-3a-phenyl-1,2,3,3a-tetrahydro-2-thioxo-5H-imidazo[4,5-c]quinolin-4(9bH)-ones in high yields. These compounds rearrange in boiling acetic acid or concentrated hydrochloric acid to give novel 5-phenyl-2-thioxospiro[4H-imidazol-4,3′-[3H]indol]-2′(1′H,3H)-ones, 5-hydroxy-5-phenyl-2-thioxospiro[imidazolidine-4,3′-[3H]indol]-2′-ones and (2-methylaminophenyl)-5-phenyl-1H-imidazole-2(3H)-thiones. All compounds were characterized by their ¹H, ¹³C, IR and MS data, and in some cases also by ¹⁵N NMR data. The structures and compositions of four compounds were confirmed by single crystal X-ray diffraction.     

AlCl3-mediated tandem Friedel-Crafts reactions of vinylidenecyclopropanes with acyl chlorides: a facile synthetic method for the construction of 1-[2-(2,2-diarylvinyl)-1-phenyl-3H-inden-5-yl]ethanone derivatives

AlCl₃-mediated tandem Friedel-Crafts reaction of vinylidenecyclopropanes with acyl chlorides produced the corresponding 1-[2-(2,2-diarylvinyl)-1-phenyl-3H-inden-5-yl]ethanone derivatives in moderate to good yields under mild conditions within short reaction time.     

Recovery of plutonium from oxalate supernatant using 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone

Summary Extraction of Pu(IV) from oxalate supernatant was carried out employing 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP) in xylene as extractant. The conditions for quantitative extraction were determined by the variation of ligand, oxalic acid and nitric acid concentration. Quantitative stripping was achieved using a mixture of 0.4M oxalic acid and 0.4M ammonium oxalate. Extraction of Pu(IV) from synthetic oxalate supernatant solution containing 3M nitric acid and 0.2M oxalic acid was investigated under various loading conditions employing 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone in xylene as extractant. Under uranium loading conditions the Pu extraction decreased significantly while with increased Pu loading whereas the D_Pu value was influenced marginally. The effect of a redox reagent on Pu extraction was also investigated.     

A molecular modelling approach to rationalize the stereochemical outcome of the Burkholderia cepacia lipase-catalyzed transesterification of aromatic primary alcohols with vinyl esters with different chain lengths in chloroform

The Burkholderia cepacia lipase-catalyzed transesterification of 2-methyl-3-phenyl-1-propanol with vinyl esters proceeds with high enantioselectivity independently of the acyl chain length and the low enantioselectivity of the same reaction with 2-phenyl-1-propanol is not affected by chain length of the vinyl esters. A molecular modelling approach has been developed in order to rationalize the enzymatic results.