Synthesis of a modified fragment 13–19 of the sequence of ACTH using silyl protection

A new scheme for the synthesis of a peptide representing a modified analog of fragments 13–19 of the sequence of the adrenocorticotropic hormone has been described, which uses a number of stages the trimethylsilyl grouping for the protection of the carboxy groups of amino acids and peptides. The final and intermediate products were obtained with high yields and were distinguished by chromatographic homogeneity.¹³C NMR was used as a supplementary method for the identification of the compounds. The physicochemical characteristics of the compounds synthesized are given.All-Union Scientific-Research Institute of the Technology of Blood Substitutes and Hormone Preparations, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 374–379, May–June, 1980.     

Synthesis of 8,8-R,R-8,9-dihydro[1,2,4]triazolo[1,5-<Emphasis Type="Italic">a</Emphasis>]quinazolin-6(7<Emphasis Type="Italic">H</Emphasis>)-ones

Three-component condensation of 3-amino-1,2,4-triazole (or its 5-methyl and 5-methylthio derivatives), dimedone (or cyclohexane-1,3-dione), and dimethylformamide dimethyl acetal afforded 8,8-R, R-8,9-dihydro[1,2,4]triazolo[1,5-a]quinazolin-6(7H)-ones. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2805–2807, December, 2005.     

Interrelation between the chemical structure and antioxidant properties of N-substituted amides of salicylic acid

The kinetics of the initiated oxidation of a model lipid (methyl oleate has been investigated in the presence of a group of new “hybrid” structures, namely, N-substituted amides of salicylic acid whose structure contains an amide residue conjugated with, or separated by a bridging fragment (three methylene groups) from, an N-phenolic substituent. The compounds also differ in the degree of screening of the OH groups. The process was initiated by thermal decomposition of azobisisobutyronitrile at 60°C (initiation rate of w _i = 4.2 × 10⁻⁸ mol L⁻¹ s⁻¹) or by UV irradiation (γ = 313−365 nm, w _i = 0.6 × 10⁻⁸ mol L⁻¹ s⁻¹). The compounds examined exhibit antiradical activity owing to the presence of the phenolic hydroxyl groups. N-substituted salicylamides efficiently inhibit the overall methyl oleate oxidation process and are comparable in activity with dibunolum and α-tocopherol or are superior to them. The structures in which the residues of salicylamide and sterically hindered phenol are separated by the bridging fragment are particularly efficient. The advantages of the salicylamides absorbing at 300–365 nm manifest themselves in UV-initiated oxidation. The peroxidase activity of the N-substituted salicyl acid derivatives is determined by the structure of the amide moiety. The compounds examined here are new, promising, effective antioxidants, whose particular structural fragments act via different mechanisms in oxidation.     

Production of high purity solution of tetraalkylammonium hydroxide using ion-exchange process

The possibility of obtaining high-purity solutions of tetramethylammonium hydroxide and tetra-nbutylammonium hydroxide was examined by passing of appropriate tetraalkylammonium halide solution through a column of an anion exchanger in the base form. Optimizing a ratio of an amount of used resin to degree of conversion determined by the residual concentration of halogen ion was demonstrated.     

Oxidative transformations of 4-(Ω-hydroxyalkyl)-2,6-di-tert-butylphenols

Conclusions Methylenequinones obtained by the oxidation of 4--hydroxyalkyl-2,6-di-tert-butyl-phenols undergo inter- and intramolecular transformations to give oligomers or tetra-hydrofuran and hydroxyketone derivatives depending on the position of the hydroxyl group in the aliphatic chain of the para substituent.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1671–1674, July, 1989.     

Preparation of hydrazides of amino acids and peptides

A new method of synthesizing hydrazides of amino acids and peptides is considered which involves the hydrazinolysis of the silyl esters of the corresponding compounds. A number of hydrazides of derivatives of amino acids and peptides has been obtained in high purity with yields close to quantitative. The physicochemical characteristics of the compounds synthesized are given.     

Reactions of perfluoro(2-methylpent-2-ene) and perfluoro(5-azanon-4-ene) with primary amines containing a 2,6-di-tert-butylphenol fragment

Reactions of perfluoro(2-methylpent-2-ene) and perfluoro(5-azanon-4-ene) with 4-(2-aminoethyl)-2,6-di-tert-butylphenol and 4-(3-aminopropyl)-2,6-di-tert-butylphenol in acetonitrile in the presence of triethylamine gave the corresponding azetidine, 1,2-dihydroazete, and 1,2-dihydro-1,3-diazete derivatives, respectively. The reaction mechanisms, role of triethylamine, and factors affecting the intramolecular nucleophilic cyclization process are discussed.