β-三氯锗基丙酸及β-三苯锗基丙酸与苯基溴化镁的反应

三氯锗基丙酸(1a)和三苯锗基丙酸(2a)与过量苯基溴化镁起反应时,这两个分子中的羧基表现出一些奇特性质。当1a和2a与不同浓度的苯基溴化镁起反应时,都能生成相应的酮(3a)和醇(4a)。在稀盐酸作用下,4a极易脱水生成1,1-二苯基-3-三苯锗基丙烯-1(5a)。当1a与苯基溴化镁起反应,然后再用稀盐酸处理也同样得到5a。5a的Ge-C键能被LiAlH~4高选择性地切断,生成三苯基锗烷(6a)和1,1-二苯基丙烯(6b)。     

Solution-phase synthesis of a combinatorial library of 3-[4-(coumarin-3-yl)-1,3-thiazol-2-ylcarbamoyl]propanoic acid amides

The parallel solution-phase synthesis of a new combinatorial library of 3-[4-(R1-coumarin-3-yl)-1,3-thiazol-2-ylcarbamoyl]propanoic acid amides 9 has been developed. The synthesis involves two steps: 1) the synthesis of core building blocks - 3- [4-(coumarin-3-yl)-1,3-thiazol-2-ylcarbamoyl]propanoic acids, 6 - by the reaction of 3-(omega-bromacetyl)coumarins 1 with 3-amino(thioxo)methylcarbamoylpropanoic acid (5); 2) the synthesis of the corresponding 3-[4-(coumarin-3-yl)-1,3-thiazol-2-yl- carbamoyl]propanoic acids amides 9 using 1,1'-carbonyldimidazole as a coupling reagent. The advantages of the method compared to existing ones are discussed.     

Enantioselective synthesis of both enantiomers of the neuroexcitant 2-amino-3-(3-hydroxy-5-tert-butylisoxazol-4-yl) propanoic acid (ATPA)

The preparation of both enantiomers of 2-amino-3-(3-hydroxy-5-tert-butylisoxazol-4-yl) propanoic acid (ATPA), 1, an analogue of the neuroexcitant 2-amino-3-(3-hydroxy-5-methyl-4-yl) propanoic acid (AMPA) is described. The enantiomerically pure glycine derivative tert-butoxycarbonyl-2-(tert-butyl)-3-methyl-4-oxo-1-imidazolidinecarboxylate (BOC-BMI) was coupled with 4-bromomethyl-2-methoxymethyl-5-tert-butylisoxazolin-3-one 6 to give the intermediates (2R,5R)-8 and (2S,5S)-8. These alkylated products were hydrolyzed under mild conditions to give enantiopure (R)-1 and (S)-1 with e.e.'s in excess of 99% in 33% overall yield.     

Reactivity of 1,6-bis(trimethylsilyl)-hexa-3-ene-1,5-diynes towards triethylborane, triallylborane, and 1-boraadamantane: first molecular structure of a 4-methylene-3-borahomoadamantane derivative, and the first 6,8-diborabicyclo[2.2.2]oct-2-ene derivative

Compounds (E)- (1) and (Z)-1,6-bis(trimethylsilyl)-hexa-3-ene-1,5-diyne (2) react with triethylborane (3) by 1,1-ethylboration in a 1:1 or 1:2 molar ratio (in the case of 1), whereas in the case of 2 only the 1:1 product is formed. The analogous reactions of 1 or 2 with triallylborane (4) are more complex because of competition between 1,1-allyl- and 1,2-allylboration. Again, compound 2 reacts only with one equivalent of 4. In the case of 1-boraadamantane (5), 1,1-organoboration of 1 and 2 takes place either at one or at both C[triple bond]C bonds leading to compounds containing the 4-methylene-3-borahomoadamantane unit(s). The product of the reaction of 1 with two equivalents of 5 was characterized by X-ray structure analysis. The primary products of the reaction of 2 with 5 rearrange upon heating by deorganoboration and organoboration to give finally a tetracyclic compound 24 that contains an exocyclic allenylidene group. The product of the 1:2 reaction of 2 with 5 rearranges to give the 6,8-dibora-bicyclo[2.2.2]oct-2-ene derivative 25. All reactions were monitored by (1)H, (11)B, (13)C, and (29)Si NMR spectroscopy.     

(S)-2-氨基-1,1-二苯基-1-丙醇的合成和外消旋Droxidopa前体的拆分

(S)-2-氨基-1,1-二苯基-1-丙醇是一种合成多种手性助剂的重要中间体,也用于外消旋屈昔多巴前体化合物的拆分。从价廉易得的L-丙氨酸出发,通过四步反应制得,总收率55.6%L-丙氨酸经甲酯化,苄氧羰基保护制得的L-2-苄羰基氨基丙酸甲酯与苯基溴化镁反应制得(S)-2-苄氧羰基氨基-1,1-二苯基-1-丙醇。是在5%Pd/C催化加氢下脱除苄氧羰基得到标题化合物。该制备方法涉及的中间体及目标化合物易于纯化,总收率高且重现性好。我们用制得的氨基醇能成功地拆分外消旋苏式屈昔多巴前体化合物3-3,4-二苄氧苯基)-N-苄氧羰基丙氨酸。     

2,5-diphenyl-3-morpholinofuran and its 2-hydro, 2-bromo and 2-hydroxymorpholinofurylium salts

2,5-Diphenyl-3-morpholinofuran ( 1 ) reacts with bromine and trifluoroacetic acid, giving respectively 2-bromo and 2-hydro furylium salts ( 2,3 ). The 2-hydroxy furylium bromide ( 4 ) was obtained by reaction of cis-morpholino-1,2-dibenzoylethylene ( 5 ) with hydrogen bromide. The nmr spectra of these salts show differences between the two morpholino dimethylene moieties of each caused by restricted rotation at the 3-immonium group. Chemical relationships studied include reductions to the morpholinofuran, conversions to 3-furanones, and the slow reaction of morpholinodibenzoylethylene with phenylmagnesium bromide to give cis-dibenzoylstyrene (13).     

Determination of the absolute configuration of chiral alpha-aryloxypropanoic acids using vibrational circular dichroism studies: 2-(2-chlorophenoxy) propanoic acid and 2-(3-chlorophenoxy) propanoic acid

The enantiomers of 2-(2-chlorophenoxy) propanoic acid and 2-(3-chlorophenoxy) propanoic acid were resolved on a chiral HPLC column and investigated using mid-infrared vibrational circular dichroism (VCD). Experimental infrared vibrational absorption and VCD spectra were measured in CDCl3 solution in the 2000-900 cm-1 region and compared with the ab initio predictions of absorption and VCD spectra. The predicted spectra were obtained with density functional theory using B3LYP/6-31G* basis set for the stable and dominant conformers. But the predicted spectra did not provide unambiguous structural information due to intermolecular hydrogen bonding in solution. To eliminate the hydrogen bonding effects, the acids were converted to the corresponding methyl esters and the experimental absorbance and VCD spectra of methyl esters were measured. B3LYP predicted spectra were also obtained for the stable and dominant conformers of the esters. From a comparison of the experimental VCD spectra of methyl esters with corresponding ab initio predictions, the absolute configurations of esters, and therefore of their parent acids, are unambiguously determined to be (+)-(R).     

A novel type of acyclic nucleoside phosphonates derived from 2-(phosphonomethoxy)propanoic acid

A convenient and efficient synthesis of a novel class of acyclic nucleoside phosphonates derived from 2-(phosphonomethoxy)propanoic acid has been developed. The key step of the synthesis is the optimized oxidation of the 3-hydroxy-2-(phosphonomethoxy)propyl (HPMP) analogues to the corresponding 2′-carboxy-PME (CPME) derivatives using the TEMPO/NaClO₂/NaClO oxidizing system. Although (S)-3-(adenin-9-yl)-2-(phosphonomethoxy)propanoic acid ((S)-CPMEA) has been designed as a compound with potential anti-HIV activity, none of the newly prepared CPME analogues exhibited any antiviral activity.     

Pyridazine Derivatives and Related Compounds,Part 1. Some Reactions with 4-Cyano-5,6-Diphenyl-2,3-Dihydropyridazine-3-One

4-Cyano-5,6-diphenyl-2,3-dihydropyridazine-3-onc 1 reacts with phosphorous oxychloride to give 70% of the corresponding 3-chloro derivative 2. Treating 2 with anthranilic acid in butanol, 4-cyano-2,3-diphenyl-10H-pyridazino[6,1-b]quinoxaline-10-one, 3 was obtained. Compound 1 reacts with phosphorous pentasulphide to give 3-mercapto derivative 4, which was converted by acrylonitrile to S-(2-cyanoethyl)pyridazine derivative 5. Compound 4 reacts with ethyl bromoacetate and with phenacyl bromide gave the corresponding thieno[2,3-c] pyridazine derivatives 8, 9, Alkylation of 1 with ethyl chloroacetate afforded 3-0-carbethoxymethyl derivative 10. Compound 10 reacts with amines (aniline, hydrazine) to give the corresponding amide and acid hydrazide 13, 12 respectively. Hydrolysis of 10 with sodium hydroxide gave the corresponding acid derivative 11. Treating 1 with methyl iodide, 3-0-methyl derivative 14 was obtained, which was converted by ammonium acetate/acetic acid to 3-amino-4-cyano-5,6-diphenyl pyridazine 15. Compound 1 reacts with methyl magnesium iodide gave 4-acetyl derivative 16, which was reacted with hydrazine, phenyl hydrazine and with hydroxylamine to give the substituted I H pyrazolo [3,4-c] pyridazine 17 a,b and isoxazolo [5,4-c] pyridazine 18 derivatives respectively.     

Novel Synthesis of 2-(2-(3-Hydroxy-5-oxo-4-phenylthiophen-2(5H)-ylidene)-2-phenylacetamido)propanoic Acid Analogues and Their Anti-Inflammatory Properties

This article describes the reaction of 3,6-diphenyl-thieno[3,2-b]furan-2,5-dione 1 with different amino acids 2a–j in glacial acetic acid which afforded the 2-(2-(3-hydroxy-5-oxo-4-phenylthiophen-2(5H)-ylidene)-2-phenylacetamido)propanoic acid analogues 3a–j and also describes the reaction of 3,6-diphenyl-thieno[3,2-b]thiophene-2,5-dione 4 with different amino acids 5a–e in acidic medium to give 2-(2-(3-mercapto-5-oxo-4-phenylthiophen-2(5H)-ylidene)-2-phenylacetamido)propanoic acid analogues 6a–e. All the compounds have been screened for their anti-inflammatory activity against the carrageenan induced rat paw edema in albino rats. In the primary screening, some of the compounds exhibited appreciable activity.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Reactions of 3-hydrazino-5,6-diphenyl-1,2,4-triazine with 4-arylidene-2-phenyl-5(4H)-oxazolones and 4-benzylidene-3-methyl-5(4H)-isoxazolone

3-Hydrazino-5,6-diphenyl-1,2,4-triazine reacts with 4-arylidene-2-phenyl-5(4H)-oxazolones in toluene to give substituted acrylic acid hydrazides, and in glacial acetic acid to give substituted imidazolones. On the other hand the hydrazinotriazine reacts with 4-benzylidene-3-methyl-5(4H)-isoxazolone, probably via a 1,4 addition reaction followed by an elimination reaction, to give benzaldehyde 5,6-diphenyl-1,2,4-triazin-3-ylhydrazone and 3-methyl-5(4H)-isoxazolone.     

Extraction and spectrophotometric determination of titanium(iv) with 3-hydroxy-2-methyl-1-(4-tolyl)-4-pyridone

Titanium(IV) in sulphuric, perchloric and hydrochloric acid media reacts with 3-hydroxy-2-methyl-1-(4-tolyl)-4-pyridone (HY) to give a complex which is extractable into chloroform. The composition of the extractable complex depends on the acidity of the aqueous phase and on which mineral acid is used. The mixed titanium-perchlorate-HY complex which is formed in the presence of excess of perchlorate is the most suitable for the spectrophotometric determination of titanium. The molar absorptivity of the complex is 1.6×10⁴1·mole^–1·cm^–1 at 355 nm. The optimum titanium concentration range is 0.5–6,g/ml. The method has been successfully applied to the determination of titanium in samples of bauxite and alumina refractory.     

Synthesis and Crystal Structure of 3-(Pyrrole-2''-carboxamido)propanoic Acid·(1/2)H2O

3-(Pyrrole-2'-carboxamido)propanoic acid I has been synthesized from the reaction of β-alanine methyl ester with 2-trichloroacetylpyrrole followed by saponifying and acidating in 85.4% yield, and the crystal structure of 3-(pyrrole-2'-carboxamido)propanoic acid· (1/2)H2O (C8H11N2O3.5, Mr = 191.19) was obtained and determined by X-ray diffraction method. The crystal is of monoclinic, space group C2/c with a = 19.010(4), b = 8.3515(17), c = 13.788(3) (A), β = 125.88(3)°, V = 1773.6(6) (A)3, Z = 8, Dc = 1.432 g/cm3, λ = 0.71073 (A), μ-MoKα) = 0.114 mm-1 and F(000) = 768. The structure was refined to R = 0.0354 and wR = 0.0942 for 1642 observed reflections with I > 2σ(I). It is revealed that the title compound has one pyrrole ring and one propionic acid subchain linked by an amido bond at C(4), and there are 8 molecules of com- pound I and 4 crystal water molecules in each unit cell. The supramolecular layers are stabilized by the hydrogen bonds of N(2) H…O(2), N(1) H…O(4), O(4) H(1W)…O(2) and O(3) H…O(1).     

Synthesis and Crystal Structure of 3-(Pyrrole-2′-carboxamido)propanoic Acid·(1/2)H_2O

1 INTRODUCTION Pyrrole and its derivatives have attracted much attention due to their chemical properties as well as biological activities[1]. They have been widely used to produce pharmaceutical, essences, biochemicals, etc. It has been found that a great number of pyrrole derivatives present antitumor and antiviral activi- ties[2 ~ 5]. During our searches for bioactive com- pounds, a series of pyrrole derivatives were synthe- sized[6, 7]. We report here the synthesis of 3-(pyrrole- 2?-…     

Convenient preparative methods for N-aryl-γ-pyridones from γ-pyrones

2-Hydroxymethyl-5-methoxy-4-H-pyran-4-one ( 1 ) reacts with aniline and six aniline derivatives in very dilute aqueous hydrochloric acid at reflux temperature to give the N-aryl-γ-pyridone. A second procedure utilizes the aromatic amine hydrochloride by reacting it with 1 in aqueous medium at reflux temperature. p-Nitroaniline hydrochloride and 1 give the N-aryl-γ-pyridone in 65% yield, as opposed to 12% from the dilute acid procedure.     

Hydrolytic opening of the quinazoline ring in 3-furfuryl-4-oxo-3,4-dihydroquinazoline derivatives

Ethyl 3-furfuryl-4-oxo-3,4-dihydroquinazoline-2-carboxylate extremely readily undergoes hydrolysis in acid, alkaline, or neutral medium with formation of 2-(2-ethoxy-1,2-dioxoethylamino)-N-furfurylbenzamide. The reaction of ethyl 3-furfuryl-4-oxo-3,4-dihydroquinazoline-2-carboxylate with phenylmagnesium bromide yields N-furfuryl-2-(2-hydroxy-2,2-diphenyl-1-oxoethylamino)benzamide as a result of hydrolytic cleavage of the quinazoline ring.     

Study of 2-(2-quinolinylazo)-5-dimethylaminobenzoic acid as a new chromogenic reagent for the spectrophotometric determination of cobalt

2-(2-Quinolinylazo)-5-dimethylaminobenzoic acid (QADMAB) is proposed as a new sensitive and selective chromogenic reagent for spectrophotometric determination of cobalt. The QADMAB reacts with cobalt in the presence of cetyl trimethylammonium bromide (CTMAB) medium to form a violet complex of molar ratio 1:2 (cobalt to QADMAB) in the pH range 3.2-5.2. The molar absorptivity of the complex is 1.28x10(5) L mol(-1) cm(-1) at 625 nm. Beer's law is obeyed in range 0.01-0.32 micro g mL(-1). The relative standard deviation for eleven replicate samples of 0.2 micro g mL(-1) is 0.76%. This method was applied to the determination of cobalt in biological samples, Vitamin B(12), alloys and water with good results.     

Kinetic modelling and simulations studies for propanoic acid esterification process

The esterification of propanoic acid with n-butanol to produce n-butyl propionate and water in the influence of an Amberlite catalyst was investigated using a batch reactor. The catalyst was chosen based on its ability to perform in this reaction. The temperature of the reaction runs between 363.15 K and 403.15 K, while the propanoic acid to n-butanol molar ratio is around 1:1 and 1:4. The selection of the catalyst loading is dependent on the volume of the reaction mixture. The catalyst dosage was kept within a 1%–3% by weight range. The kinetics of conversion have been researched in relation to the reaction temperature, mole ratio, catalyst size, stirrer speed, and catalyst quantity. The catalyst dosage and reaction temperature, according to the study, have a substantial influence on how soon the system achieves equilibrium. The pseudo homogeneous kinetic model is developed and tested against experimental results. Under the specified conditions, model predictions and empirical observations accord well. Arrhenius equation was used for calculation of rate constants and energy of activation. The forward reaction's frequency factor & activation energy are 18.554 L/mol.min and 30350 J/mol, correspondingly. Since the equilibrium constant increases as the temperature rises, the reaction is endothermic.     

3-(2-氧代环烷基)丙酸与(R)-2-硫代四氢噻唑-4-羧酸乙酯的反应

３－（２－氧代环烷基）丙酸与（Ｒ）－２－硫代四氢噻唑－４－羧酸乙酯的反应李叶芝,田颜清,黄化民（吉林大学化学,长春,１３００２３）关键词（Ｒ）－２－硫代四氢噻唑－４－羧酸乙酯,Ｎ－３－（２－氧代环烷基）丙酰－２－硫代四氢噻唑－４－羧酸乙酯,环合反应,...     

Vibrational spectroscopy investigation using ab initio and density functional theory analysis on the structure of 3-(6-benzoyl-2-oxobenzo[d]oxazol-3(2H)-yl)propanoic acid

The molecular structure, vibrational frequencies and infrared intensities of the 3-(6-benzoyl-2-oxobenzo[d]oxazol-3(2H)-yl)propanoic acid were calculated by the HF and DFT methods using 6-31G(d) basis set. The FT-infrared spectra have been measured for the title compound in the solid state. We obtained 11 stable conformers for the title compound, however the Conformer 1 is approximately 3.88 kcal/mol more stable than the Conformer 11. The comparison of the theoretical and experimental geometry of the title compound shows that the X-ray parameters fairly well reproduce the geometry of the Conformer 1. The harmonic vibrations computed of this compound by the B3LYP/6-31G(d) method are in a good agreement with the observed IR spectral data. Theoretical vibrational spectra of the title compound were interpreted by means of PEDs using VEDA 4 program.