Catalysis of the dealkylation of derivatives of 2,6-di-tert-butylphenol by heteropoly acids

Conclusions The tungsten heteropoly acids in acetic acid are the most active in the dealkylation of 4-alkyl-2,6-di-tert-butylphenols. The reaction is first order with respect to the substrate and with respect to the HPA, and water slows the reaction. It has been postulated that the dealkylation reaction is mediated mainly by the undissociated molecules of the HPA.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 752–756, April, 1987.     

Use of the silylation reaction in synthesis of fragment 1–4 of the ACTH sequence

A new effective method of synthesizing fragment 1–4 of the ACTH sequence ensuring a high overall yield of the desired product is proposed. This result is achieved thanks to the wide use of the silylation reaction in the synthesis, which has permitted a considerable simplification of the process and the avoidance of the formation of by-products. The peptides synthesized have been characterized by their angles of optical rotation, chromatographic mobilities, and melting points. A table of chemical shifts in the¹³C NMR spectra of the final and intermediate compounds is given.All-Union Research Institute of Technology of Blood Substitutes and Hormone Preparations, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 248–253, March–April, 1988.     

γ-hydroxypropylation of 2,6-dialkyl(aryl)phenols with allyl alcohol and its derivatives

The composition of the products of the reaction of 2,6-disubstituted phenols with allyl alcohol and its derivatives in an alkaline medium was investigated, the conditions for carrying out the reaction with the predominant formation of 4-(3-hydroxypropyl)-2,6-dialkyl(aryl)phenols were found, and its mechanism was suggested. The reaction was examined on an industrial scale. An important result is the practical demonstration of alkaline catalysis performed under homogeneous conditions with participation of phenols, when the used alkaline catalyst is recovered in the process without the formation of waste waters.     

Photochemistry of <Emphasis Type="Italic">N</Emphasis>-substituted salicylic acid amides

The products of photolysis of N-substituted salicylic acid amides, viz., 2-hydroxy-3-tert-butyl-5-ethylbenzoic acid N-(4-hydroxy-3,5-di-tert-butylphenyl)amide (1) and 2-hydroxybenzoic acid N-[3-(4-hydroxy-3,5-di-tert-butylphenyl)prop-1-yl]amide (2), in heptane were studied by optical spectroscopy and stationary and nanosecond laser photolysis (Nd: YAG laser, 355 nm). It was shown by the method of partial deuteration of amides 1 and 2 that they exist in both the unbound state and as complexes with intraand intermolecular hydrogen bond. Amides 1 and 2 are subjected to photolysis, which results in the formation of a triplet state and phenoxyl radicals RO? presumably due to the absorption of the second photon by the excited singlet state. The formation of radical products due to N–H bond ionization was not observed. The main channel of decay of the triplet state and radicals RO? is triplet–triplet annihilation and recombination (k _r ≈ 2.3?10⁸ L mol^–1 s^–1), respectively. The UV irradiation of compounds 1 and 2 leads to the excitation of the amide groups, and no formation of radical products due to N–H bond ionization was observed.     

Synthesis of the N-terminal tripeptide of the oxytocin sequence

Two schemes for the synthesis of the hydrazide of the N-terminal tripeptide of the oxytocin sequence are considered. It is shown that the most rational is a 1 + 2 scheme.All-Union Scientific-Research Institute of the Technology of Blood Substitutes and Hormone Preparations, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 116–122, January–February, 1989.     

Development of a one-stage synthesis of 2,6-di-<Emphasis Type="Italic">tert</Emphasis>-4-ethylbutylphenol from 2,6-di-<Emphasis Type="Italic">tert</Emphasis>-butylphenol

Investigation of the catalyzed reaction of 2,6-di-tert-butylphenol with ethanol, ethylene glycol, oligomeric glycols, and paraldehyde in a strongly basic medium permitted to develop a technologically suitable procedure for manufacture of 2,6-di-tert-4-ethyl-butylphenol, used in the synthesis of Antioxidant-425.     

Synthesis of a decapeptide with the sequence 1–10 of human calcitonin with minimum protection of the amino acids

A decapeptide with sequence 1–10 of human calcitonin has been synthesized by a 5+5 scheme with the minimum protection of the side-chain functional groups of the amino acid.All-Union Scientific-Research Institute of the Technology of Blood Substitutes and Hormonal Preparations, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 381–387, May–June, 1985.