A palladium catalyzed efficient synthesis of γ-methylene-α,β-unsaturated γ-lactones via cyclization of 3,4-alkadienoic acids

An efficient method was developed for the synthesis of γ-methylene-α,β-unsaturated γ-lactones from the Pd-catalyzed cyclization of 3,4-alkadienoic acids. Control experiment shows that the reaction should be carried out under a N₂ atmosphere to ensure the high purity of the products.     

Photolysis (193 nm) of aliphatic amino acids in aqueous solution

An investigation of the photochemical properties of glycine, aspartic acid, valine, leucine and methionine was carried out using nanosecond 193 nm laser irradiation and high performance liquid chromatography analysis. The quantum yields of formation of hydrated electrons (Φ_e−) and decomposition of the substrate (Φ_d) were determined for the five aliphatic amino acids in neutral aqueous solution at room temperature. From the dependences of Φ_e− on the laser intensity it follows that the mechanism of photo-ionization is monophotonic (single step). The Φ_d values under Ar and in the presence of oxygen or N₂O are interpreted on the basis of photo-ionization as the dominant process for decomposition of methionine and a significant contribution from photo-ionization in the other cases. A comparison was made between the Φ_d values (in the presence of oxygen) using irradiation at 193 nm and those from previous measurements at 213 nm.     

气相色谱－质谱法测定赤鳞鱼肉中的脂肪酸

利用气相色谱质谱（ＧＣ／ＭＳ）电子轰击方法，对６种不同年龄和不同性别的赤鳞鱼肉中的饱和、不饱和脂肪酸（经甲酯化后）进行了测定，用色谱法作了定量，共鉴定出１８种脂肪酸。     

Synthesis and properties of methyl hydropyrimidineacetates

The alkylation of 1-aryl-substituted dihydro-2,4(1H,3H)-pyrimidinediones with methyl 2-bromoacetate has been studied followed by hydrolysis and condensation of the products with o-phenylenediamine. The compounds have been identified by NMR, and IR spectrometry and mass spectrometry. Structural characteristics in the ¹H and ¹³C NMR spectra of the synthesized are discussed. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, 1095–1105, July, 2007.     

Synthesis of Betulonic Acid Derivatives Containing Amino-Acid Fragments

New derivatives of betulonic acid containing on C-28 fragments of amino acids or their methyl esters were prepared as potential biologically active agents.     

Alkyl 2-chloro-3,3,3-trifluoro-2-isocyanatopropionates

Earlier unknown representatives of fluorine-containing α-chloroalkylisocyanates, viz., esters of 2-chloro-3,3,3-trifluoro-2-isocyanatopropionic acid, were obtained. Synthetic potentialities of these compounds in the preparation of 2-substituted derivatives of 3,3,3-trifluoroalanine were demonstrated. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2179–2181, November, 2007.     

Synthesis of Pyridazinone Derivatives

The reaction of methyl esters of 3-methyl-2-oxo- and 2-oxo-3-phenyl-3-pentenoic acids with hydrazine hydrate and phenylhydrazine was used to synthesize new pyridazinone derivatives. These products are formed through intermediate hydrazides with subsequent cyclization. 4-Hydroxy-3-oxotetrahydropyridazines are mainly formed using equimolar amounts of the starting reagents, while the corresponding hydrazones of 3,4-dioxohexahydropyridazines are formed in the case of a two-fold excess of hydrazine hydrate or phenylhydrazine. Evidence was obtained indicating the existence of a keto–enol tautomerism for 4-hydroxy-3-oxopyridazines.