Synthesis of esters of α-vinyloxyethylcarbamodithioic acid

Mono and diesters of 2-vinyloxyethylcarbamodithioic acid were synthesized by the reaction of (1-p-nitrophenyl)-2-vinyloxyethylaminoethanol with carbon disulfide. 3-[2-(Vinyloxyethyl)]-5-(4-nitrophenyl)-1,3-thiazolidine-2-thione was prepared and its structure was proved by X-ray diffraction analysis.     

Synthesis of Ω-aminododecanoic acid

Summary A synthesis of-aminododecanoic acid has been carried out starting with trans,trans,trans-cyclododecatriene1,5,9.     

Synthesis of azo derivatives of 4-aminosalicylic acid

For searching a better 4-aminosalicylic acid derivative with higher activity and less side effects against the inflammatory bowel disease, 4-aminosalicylic acid (4-ASA) was protected by benzyloxycarbonyl and acetyl, respectively. The resultant was hydrogenized to remove protective group of amino group, then the product was reacted with NaNO2 to give diazonium salt, which was conjugated with salicylic acid, hydroxybenzene, TV-salicyloyl glycine acid to get azo derivatives of 4-ASA. The azo derivatives were hydrolyzed under the alkaline condition to get the target products. All compounds were characterized by FT-IR, 1H NMR, 13C NMR spectra in details. New derivatives of 4-ASA were characterized. The synthetic route was reasonable and feasible.     

Crystal structure of α-cyanoacrylic acid

An x-ray structural investigation of -cyanoacrylic acid has been carried out (R=0.058 on the basis of 767 reflections). The molecules in the crystal are joined by strong O–H...N hydrogen bonds in zigzag chains along the [101] direction. The relative arrangement of the double bonds of neighboring molecules does not satisfy the conditions for topochemical reactions in crystals of compounds with C=C double bonds, in agreement with the stability of the crystals of -cyanoacrylic acid toward illumination and prolonged exposure to x rays.A. N. Nesmeyanov Institute of Organometallic Compounds, Academy of Sciences of the USSR. Translated from Zhurnal Strukturnoi Khimii, Vol. 32, pp. 139–143, March–April, 1991.     

Thermochemical study of the reactions of acid–base interaction in an aqueous solution of α-aminobutyric acid

The heat effects of the interaction between a solution of α-aminobutyric acid and solutions of HNO₃ and KОН are measured by means of calorimetry in different ranges of рН at 298.15 K and values of ionic strength of 0.25, 0.5, and 0.75 (KNO₃). The heat effects of the stepwise dissociation of the amino acid are determined. Standard thermodynamic characteristics (Δ_r H ⁰, Δ_r G ⁰, and Δ_r S ⁰) of the reactions of acid–base interaction in aqueous solutions of α-aminobutyric acid are calculated. The connection between the thermodynamic characteristics of the dissociation of the amino acid and the structure of this compound is considered.     

Formulation ofα-linolenic acid microemulsion free of co-surfactant

<正>A novel class ofα-linolenic acid-in-water microemulsion free of co-surfactant was investigated as potential food delivery systems.Rough demarcation within the transparent region was deduced from the results of conductivity and polarizing optical microscopy.The microemulsion mean hydrodynamic diameter and characterization were determined by dynamic light scattering and negative-staining TEM.The location of ALA molecules in the microemulsion formulations was determined by ~1H NMR spectroscopy.     

Cyclization of the methyl ester of α-propionyllevulinic acid

Summary Cyclization of methyl -propionyllevulinate to 2,3-dimethylcyclopenten-2-one and methyl 3,4-dimethylcyclopenten-3-one-2-carboxylate was accomplished.     

Biodegradation of β-1,4-linked polyglucuronic acid (cellouronic acid)

Biodegradability of -1,4-linked polyglucuronic acid (cellouronicacid), which was prepared from regenerated cellulose by2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation underaqueous conditions, was examined by enzymatic treatments and incubationtreatments with microorganisms collected from some soil samples. Degradation ofcellouronic acid was traced by size exclusion chromatography (HPSEC) or totalorganic carbon (TOC) of the treated products or solutions, respectively.Cellouronic acid was depolymerized by a commercial crude cellulase anddecreasedin its weight average degree of polymerization from about 1600 to 40 by thecellulase treatment at 20 °C for 40 days. ¹³C-NMRanalysis and liquid chromatography of the treated products showed thathydrolysis-type enzymes present in the crude cellulase as contaminantsprimarilydepolymerized cellouronic acid to give glucuronic acid. When aqueous solutionscontaining cellouronic acid were incubated with soil microorganisms for morethan 3 days, the TOC values decreased to less than 20% of the initial value,depending on molecular weight of the cellouronic acid used. The decreasing rateof TOC for cellouronic acid was clearly higher than that ofcarboxymethylcellulose, which is one of the cellulose derivatives havingcarboxymethyl substituents. These results imply that cellouronic acid has bothbiodegradability and metabolizability in the natural environment.     

Investigation of the phosphinyl analog of α-ketoglutaric acid

It was shown by³¹P and¹³C NMR spectroscopy that methyl(3-carboxy-3-oxopropyl)phosphinic acid (4-methylhydroxyphosphinyl-2-oxobutyric acid) (1) and the amide (2) of the latter exist in keto forms in non-aqueous solutions. In aqueous solutions an equilibrium between the keto,gem-diol, and enol forms has been observed. The proportions of the diol and enol forms increase as the acidity of the media increases. Silylation of acid 1 with hexamethyldisilazane gives the tris(trimethylsilyl) derivative of enol form (3) (Z- andE-isomers).Translated fromIzyestiya Akadetnii Nauk. Seriya Khimicheskaya, No. 1, pp. 125–128, January, 1994.     

Conformational study of α-arylethylamides of (−)-camphanic acid

The absolute conformation and configuration of diastereomeric amides (4A,B–6A,B) of (1S,3R)-camphanic acid (lactone of 1-hydroxy-2,2,3-trimethylcyclopentan-1,3-dicarboxylic acid, (−)-camphanic acid 9) with α-arylethylamines 1–3 are deduced from ¹H NMR data and MM2 calculations. The α-arylethyl group in diastereomers A and B adopt nearly opposite absolute conformations, stabilized by hydrogen bonding in the syn-oriented O–C(1)–C(6)–N–H unit, and repulsive interaction between the 1′C–Me group and the amide CO group. The absolute configuration (1′S) is assigned to the 4A–6A diastereomers, and the (1′R)-configuration to the 4B–6B diastereomers; this assignment is confirmed by the preparation of 4A and 5A from enantiomerically pure (1′S)-α-arylethylamines 1 and 2, respectively. These results also enabled the assignment of pro-R (H_R) and pro-S (H_S) protons in the benzyl derivative 7.     

Seven-step total synthesis of α-cyclopiazonic acid

A seven-step total synthesis of α-cyclopiazonic acid is reported from a commercially available 4-bromoindole.Salient feature of the work is the rapid formation of tetracyclic skeleton via a bioinspired [3+2] annulation to form the C/D rings.     

Preparation of chiral α-diazophosphonic acid derivatives

The chiral α-diazophosphonic acid derivatives 3, 6 and 8 were prepared from (−)-ephedrine and (S,S)-N,N′-dimethyl-1,2-diaminocyclohexane; preliminary experiments suggest that the chiral auxiliary exerts little influence in the dirhodium(II) acetate catalysed OH and NH insertion reactions.     

Microbial production of natural poly amino acid

Three kinds of poly amino acids, poly-γ-glutamic acid, poly(ε-L-lysine) and multi-L-arginyl-poly (L-aspartic acid) can be synthesized by enzymatic process independently from ribosomal protein biosynthesis pathways in microorganism. These biosynthesized polymers have attracted more and more attentions because of their unique properties and various applications. In this review, the current knowledge on the biosynthesis, biodegradations and applications of these three poly amino acids are summarized.     

Synthesis and properties of fibers prepared from lactic acid–glycolic acid copolymer

A method for preparing laboratory samples of fibers from glycolide-co-D,L-lactide to produce bioresorbing suture filaments with a controlled complex of properties is developed. The morphology of fibers obtained through melt spinning is studied. The peculiarities of the mechanical properties of fibers are investigated.     

Formation of hyaluronic acid–ellagic acid microfiber hybrid hydrogels and their applications

Microfiber assemblies prepared from ellagic acid (EA) were functionalized with histidine (His) and dispersed in hyaluronic acid (HA) hydrogel microstructures. Swelling studies indicated that the hybrids had a relatively lower water uptake compared to HA and was pH dependent. The percentage swelling ratio for EA–His–HA hybrids was 48 % when 0.04 mg/mL of HA was incorporated and increased to 70 % when 1.2 mg/mL HA was integrated. Release studies using the dye crystal violet (CV) as a model drug showed that the rates were concentration-dependent. Further the hybrids were found to be thermally stable compared to HA. Cellular toxicity assays performed with normal rat kidney (NRK) cells indicated biocompatibility and adherence of the hybrids to the cells. Thus, we have developed a new family of hybrid hydrogels which readily formed on the EA–His functionalized microfibers and may have potential applications in drug delivery or tissue regeneration applications.     

Thermophysical property characterization of aqueous amino acid salt solutions containing α-aminobutyric acid

In this study, density, electrical conductivity, refractive index and viscosity of aqueous potassium and sodium salt solutions of α-aminobutyric acid were presented. Measurements were done over the temperature range (303.15 to 343.15) K and atmospheric pressure for salt compositions from x₁ = 0.009 to 0.062. A modified Graber et al. equation was used to correlate the density, electrical conductivity, and refractive index with temperature and composition leading to average absolute deviations (AAD) between the predicted and calculated values of 0.04%, 0.7%, and 0.01%, respectively. The viscosity data were represented as a function of temperature and composition via Vogel–Tamman–Fulcher (VTF) type equation at an AAD of 0.6%.     

The features of nitric acid ‘mercerization’ of cellulose

Transformation of native cellulose species into cellulose-II polymorph through the additive Knecht compound formed under the action of 68.5% nitric acid has been studied. Probable causes of peculiar temperature effects in the course of phase transformations taking place in cellulose of various origin, crystallite dispersity, or morphologic structure are discussed. The processes of hydrolytic destruction and esterification of starting materials during their mercerization by this non-traditional agent at 20 °C and 0 °C are quantitatively characterized. In the case of mercerization of wood microcrystalline cellulose at 20 °C a decrystallizing effect due to side reactions of partial nitration is noted.     

Structural variations of N-acetylneuraminic acid, 24: Synthesis of the α-methylketoside of 8-oxo-N-acetylneuraminic acid and related derivatives

The synthesis of the sodium 5-acetamido-2,3,5-trideoxy-2,3 didehydro-D-galacto-2,8-nondiulopyranosidonate 8,8-dimethyl acetal (8) and of the methyl-5-acetamido-3,5-dideoxy--D-galacto-2,8-nondiulopyranosidonate 8,8 dimethyl acetal (11) as well as of the methyl-5-acetamido-3,5-dideoxy--D-galacto-2,8-nondiulopyranosidonic acid (12) is reported involving the easily accessible 8-oxoderivative5. Compounds11 and12, respectively, showed to have glycosidic bond with remarkable stability to acidic conditions.

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Strukturelle Variationen an N-Acetylneuraminsäure, 24. Mitt.: Synthese des -Methylketosids von 8-Oxo-N-acetylneuraminsäure und verwandten Derivaten

Zusammenfassung Es wird ein Zugang zu Natrium-(5-acetamido-2,3,5-trideoxy-2,3-didehydro-D-galacto-2,8-nondiulopyranosid)onat-8,8-dimethylacetal (8), Methyl-5-acetamido-3,5-dideoxy--D-galacto-2,8-nondiulopyranosidonat-8,8-dimethyl acetal (11) und Methyl-5-acetamido-3,5-dideoxy--D-galacto-2,8-nondiulopyranosidonsäure (12) über ein gemeinsames, leicht herzustellendes 8-Oxo-Sialinsäurederivat5 beschrieben. Die glycosidische Bindung der Verbindungen11 bzw.12 zeigt eine bemerkenswerte Stabilität gegenüber sauren Reaktionbedingungen, welche im Gegensatz zu Beobachtungen an anderen Neuraminsäuremethylketosiden steht.