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Vol 60, No 7 (2024)
Articles
Structural analogues of thyronamines. Experimental and DFT calculated NMR 1H chemical shifts of 4-[4-(2-aminoethoxy)benzyl]aniline
Abstract
The paper presents the results of molecular modeling of the structure and evaluation of the 1Н nuclei chemical shifts of a new structural analog of endogenous thyronamines, 4-[4-(2-aminoethoxy)benzyl]aniline. For 4-[4-(2-aminoethoxy)benzyl]aniline, the molecular geometry was optimized at the B3LYP level with basis sets 6-31G(d,p), 6-31+G(d,p), 6-311G(d, p) both in the approximation of an isolated molecule and with allowance for the solvent. The 1H nuclei chemical shifts of 4-[4-(2-aminoethoxy)benzyl]aniline were estimated on the base of the magnetic screening constants calculated by the GIAO method. The nonspecific solvation with dimethyl sulfoxide and methanol within the polarized continuum model (IEFPCM) was taken into account both in optimizing the molecular geometry and in calculating the magnetic screening constants. The calculated chemical shifts of the 1H nuclei for 4-[4-(2-aminoethoxy)benzyl]aniline are in good agreement with the experimental ones obtained in DMSO-d6 as well as CD3OD solutions. Linear correlations were obtained between the calculated and experimental data.
815-824
Peculiarities of the ketogroup reduction in the synthesis of mono- and dialkyl-substituted derivatives of benzo[b]benzo[4,5]-thieno[2,3-d]thiophene
Abstract
Mono- and dioctyl-substituted benzo[b]benzo[4,5]-thieno[2,3-d]thiophene derivatives, C8-BTBT and C8-BTBT-C8, have been synthesized, widely used as organic semiconductors for the manufacture of various organic electronics devices. The preparation of target molecules was carried out in 2 stages: acylation of BTBT according to Friedel—Crafts and subsequent reduction of the ketogroup. Since the rate-limiting step in the preparation of such compounds is reduction, various approaches to the reduction of acyl-substituted BTBT derivatives have been investigated and possible mechanisms for these reactions have been proposed. It has been shown that the most effective reduction occurs using hydrazine hydrate.
825-837
Synthesis and properties of 1,3-disubstituted ureas and their isosteric analogues containing polycyclic fragments: XX. 1-[(3,5-difluoroadamantan-1-yl)]-3-R-ureas and symmetric diureas
Abstract
A method has been developed for the production of (3,5-difluoroadamantan-1-yl) isocyanate from 3,5-difluoroadamantan-1 carboxylic acid and diphenyphosphoryl azide, using a new fluorinating agent, the Ishikawa reagent, at one of the synthesis stages. Reaction of (3,5- difluoroadamantane-1-yl)isocyanate with aliphatic diamines and trans-4-amino(cyclohexyloxy)A series of 1,3-disubstituted urea and dimourea with yields of 43-96% was synthesized with benzoic acid. By hydrolysis of (3,5-difluoroadamantan-1-yl)isocyanate in the presence of catalytic amounts of DBU, a symmetrical 1,3-bis(3,5-difluoroadamantan-1-yl) was obtainedurea with a yield of 47%.The influence of the number of fluorine atoms in the adamantile substituent on the melting temperatures and lipophilicity of urea has been established, which makes it possible to purposefully regulate these important properties of urea as potential enzyme inhibitors.
838-847
Possible skeletal transformations of pyridine and phosphinine during their thermal isomerization
Abstract
Based on the properties of the of p-electron conjugated system in cyclic polyenes, possible spatial structures of the transition states of the thermal isomerization reactions of pyridine and phosphinine in an oxygen-free atmosphere were found. The existence of transition states is determined by different levels of the stabilization effect of the p-electron conjugation. The determination of the spatial and electronic characteristics of the transition states of pyridine and phosphinine was carried out by the DFT/B3LYP/6-31G* method. Schemes were constructed and potential barriers of the thermal isomerization reactions of pyridine and phosphinine were calculated. A study of the reactivity of the pyridine and the phosphinine in thermal isomerization processes showed a decrease in the degree of aromaticity of phosphinine compared to pyridine.
848-857
Regioselective C(7)–H arylation of 2-(het)aryl [1,2,4]triazolo[1,5-a]pyrimidines by aryl halides under ruthenium catalysis
Abstract
An unusual selectiviry of C-H arylation reactions of 2-(hetero)aryl[1,2,4]triazolo[1,5-a]pyrimidines with (hetero)aryl halides catalyzed by Ru(II) complexes was revealed. The reaction proceeds with activation of the C(7)-H bond rather than the α-C-H bond of the (hetero)aryl substituent at position 2 of the triazolopyrimidine. Arylation of 2-substituted [1,2,4]triazolo[1,5-a]pyrimidines with (hetero)aryl bromides afforded a series of 7-(hetero)arylated products in good yields.
858-867
New cross-conjugiated chlorocyclopentenone derivatives containing amino acids fragments at C-3
Abstract
The reaction of 5-allenyl-2,3,5-trichlorocyclopentenone with methyl esters of glycine, L-methionine, L-leucine and L-tyrosine produced the corresponding AdNE adducts, the oxidative cleavage of the allene fragment of which produced new 4-carboxymethylidene derivatives.
868-874
Synthetic pathway of [2,4-dichloro-6-(3,5-dichloro-2-hydroxybenzamido)phenoxy]acetic acid
Abstract
Synthetic route of 3,5-dichlorosalicylic acid anilide containing carboxymethoxy-group in aniline fragment in ortho-position to amide group was proposed. The intermediate was 2-(2-nitro-4,6-dichlorophenoxy)-N,N-dimethylacetamide which was reduced to amine and acylated with 3,5-dichloro-2-hydroxybenzoyl chloride, and then protective N,N-dimethylamide group was selectively hydrolyzed in alkaline medium. Without protection of the carboxyl group, reaction with 3,5-dichloro-2-hydroxybenzoyl chloride affords mainly 6,8-dichloro-2H-1,4-benzoxazin-3(4H)-one.
875-882