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Dimedone is added at C(5) of 3-phenyl-1,2,4-triazine to give stable dihydro derivative. Its reaction with 1-aryl-3-methylpyrazol-5- ones proceeds with fragmentation affording 1,1,2,2-tetrakispyrazolylethane and amidrazone derivatives. [ABSTRACT FROM AUTHOR]

Abstract: Reactions of 3-amino-4H-chromeno[3,4-d]isoxazol-4-ones with acetic and trifluoroacetic anhydrides gave the corresponding acetyl derivatives, which were rearranged into 2-amino-4H-chromeno[3,4-d][1,3]oxazol-4-ones by heating in DMSO solution. [Copyright &y& Elsevier]

The competitive routes were found for three-component cyclization of polyfluoroalkyl-3-oxo esters, methyl ketones with 3-amino alcohols. It was shown that the reactions with 3-aminopropanol in 1,4-dioxane predominantly lead to hexahydropyrido[2,1-b][1,3]oxazin-6-ones, and in ethanol to 3-hydroxypropylaminocyclohexenones. In contrast, cyclizations with 2-aminoethanol and its analogues, regardless of the reaction conditions, yield hexahydrooxazolo[3,2-a]pyridin-5-ones as the main products. The trans- and cis-diastereomeric structure of heterocycles was established using X-ray and 1H, 19F, 13C NMR spectroscopy, 2D 1H-13C HSQC and HMBC experiments. The mechanism is proposed for competitive transformations of polyfluoroalkyl-3-oxo esters, methyl ketones with 3-amino alcohols. [ABSTRACT FROM AUTHOR]

Stereoselectivity in the mutual kinetic resolution (KR) of racemic 3,4‐dihydro‐3‐methyl‐2H‐[1,4]benzoxazines and racemic 2‐aryloxy propionyl chlorides was studied. Based on the results obtained, preparative methods for single enantiomers of a series of 2‐aryloxy propionic acids via acylative KR of their racemates with enantiopure (S)‐3,4‐dihydro‐3‐methyl‐2H‐[1,4]benzoxazines have been proposed. [ABSTRACT FROM AUTHOR]

Novel conjugates of 2‐aminopurine and purine containing fragments of chiral heterocyclic amines attached at position 6 of purine core via a linker, fragment of omega‐amino acid, have been synthesized and evaluated in vitro for their anti‐herpetic activity in the Vero E6 cells; as a result, a new group of compounds possessing high inhibitory activity against herpes simplex virus type 1, including acyclovir‐resistant (TK–) strain has been revealed. The anti‐herpetic activity of the synthesized compounds is substantially dependent on the stereo configuration of the fragment of heterocyclic amine. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Racemic 3,4-dihydroferroceno[ c ]pyridines were obtained via the Ritter reaction. • MsOH-catalysed reaction of 2-methyl-1-ferrocenylpropan-1-ol with nitriles. • Preparative chiral HPLC resolution of the racemic 3,4-dihydroferroceno[ c ]pyridines. • Assignment of absolute configuration of (R p)- and (S p)-enantiomers by X-ray. Abstract A new approach for the synthesis of functionalized racemic 3,4-dihydroferroceno[ c ]pyridines via the Ritter reaction of 2-methyl-1-ferrocenylpropan-1-ol with nitriles in the presence of methansulfonic acid was developed. The scope and limitations of the reaction were evaluated. Selected racemic 3,4-dihydroferroceno[ c ]pyridines were successfully separated by preparative HPLC on a Chiralcel OD-H column. The absolute configuration of the enantiomers was determined by X-ray crystal structure analysis. [ABSTRACT FROM AUTHOR]

The alkylation of 4-methylquinolin-2(1Н)-one with methallyl chloride gave a regioisomer mixture containing 1-methallyl-4-methylquinolin-2(1Н)-one and 2-methallyloxy-4-methylquinoline, which reacted with iodine and bromine and formed dihydrooxazolo[3,2-а]- quinolinium systems. [ABSTRACT FROM AUTHOR]

An efficient method for incorporation of the cyanomethyl fragment into the benzene ring of bi- and tricyclic fluoroquinolones through the nucleophilic substitution of a fluorine atom with carbanions derived from CH-active cyanoacetates, followed by an acidic hydrolysis of the reaction intermediates was developed. The reaction of cyanomethyl derivatives of bi- and tricyclic fluoroquinolones with ortho -hydroxy substituted benzaldehydes proved to give the corresponding condensation products, which can be regarded as the key intermediates in the synthesis of previously unknown (2-oxo-2 H -chromen-3-yl) substituted bi- and tricyclic fluoroquinolones. It has been shown that an increase in the reaction temperature and exposition time promotes the competitive process, leading to substitution of one more fluorine atom to give 1,4-dihydro[1]-benzoxepino[2,3- g ]quinolones. New fluoroquinolones proved to exhibit anti-mycobacterial activity, thus indicating that a search of biologically active compounds in this family of heterocycles appears to be a reasonable approach. [ABSTRACT FROM AUTHOR]

Photoinduced transformations of (E) -2-(2-hydroxystyryl)quinazolinone-linked benzo[15(18)]crown-5(6) ethers in solutions have been studied by using UV–vis absorption and NMR spectroscopy. These crown ethers were found to have dual emission at 520 and 650 nm, associated with proton-transfer tautomer emission (ESIPT-luminescence) as a rare case of excited-state proton-transfer reaction in the non-pseudocyclic chromophoric systems. It was established also, that the organic bases affect the luminescence intensity of solutions of these compounds in the 550–650-nm wavelength range. An X-ray crystallography analysis of molecular structures of crown ethers and their complexes in crystals has been carried out. The fact of reversible photo/thermal E - Z isomerization in DMF and Et 3 N for these macroheterocyclic compounds has been confirmed. An opportunity to control the photochemical isomerization rate of quinazolinone 2-(hydroxyphenyl)ethenyl derivatives by changing pH of the medium has been demonstrated. [ABSTRACT FROM AUTHOR]

Graphical abstract Novel tetracyclic 5-aryl-5,6-dihydroquinolino[2,1- b ]quinazolin-12-ones bearing benzo-15-crown-5 ether and dimethoxyphenyl moieties were prepared by one-pot cascade synthesis involving the thermally allowed pericyclic transformations of (E)-2-(2-methoxystyryl)quinazolinones. The pseudocyclic transition state of six-electron electrocyclization has been located and the activation barrier has been estimated by RHF/3-21G and 6-311G* calculation methods. The crystal structure of N -[4-(2,3-dimethoxy-12-oxo-5,6-dihydroquinolino[2,1- b ]quinazolin-5-yl)-3-methoxyphenyl]acetamide was determined by X-ray diffraction analysis. [ABSTRACT FROM AUTHOR]

The acylative kinetic resolution of racemic heterocyclic amines such as 3,4-dihydro-3-methyl-2 H -[1,4]benzoxazines, 3,4-dihydro-3-methyl-2 H -[1,4]benzothiazine, 2-methyl-1,2,3,4-tetrahydro-quinolines and 2-methylindoline with enantiopure ( R )-2-phenoxypropionyl chloride has been studied. It has been found that acylation of 3,4-dihydro-3-methyl-2 H -[1,4]benzothiazine proceeds with the best stereoselectively when compared with other racemic amines. An efficient method for the preparation of ( S )-3,4-dihydro-3-methyl-2 H -[1,4]benzothiazine (99.4% ee ) via a kinetic resolution protocol was developed. The possibility of recycling ( R )-2-phenoxypropionic acid has been demonstrated. [ABSTRACT FROM AUTHOR]

Reactions of 2-R-3-nitro-2 H -chromenes (R=CF 3 , CCl 3 , Ph) with α-morpholinostyrene in acetonitrile proceed diastereoselectively to give mainly trans – cis -2,3,4-trisubstituted chromane enamines at room temperature and trans – trans -chromane enamines at 60 °C as a result of nucleophilic addition at the C-4 atom of the chromene system. Acid hydrolysis of these compounds proceeded with retention of the configuration of the pyran ring and gave 4-phenacylchromanes. The stereochemistry of the products was established by X-ray diffraction analysis. [ABSTRACT FROM AUTHOR]

Reactions of 2-R-3-nitro-2 H -chromenes (R=CF 3 , CCl 3 , Ph) with aminoenones derived from acetylacetone and cyclic amines (morpholine, piperidine) proceed diastereoselectively to give mainly cis – trans -2,3,4-trisubstituted chromanes as a result of nucleophilic addition of the vinylogous β-methyl group at the C-4 atom of the chromene system. From these compounds, under acidic conditions, 4-acetoacetonyl-3-nitrochromanes and 5 H -chromeno[3,4- b ]pyridines, depending on the substituent at the 2-position, were obtained in moderate to good yields. Similar results, except for the synthesis of 5 H -chromeno[3,4- b ]pyridines, were obtained by replacing acetylacetone with benzoylacetone. The stereochemistry of the products was established by X-ray diffraction analysis. [ABSTRACT FROM AUTHOR]

In the search for novel efficient chiral resolving agents, we have studied the diastereoselective acylation of 3,4-dihydro-3-methyl-2 H -[1,4]benzoxazine and 7,8-difluoro-3,4-dihydro-3-methyl-2 H -[1,4]benzoxazine with acyl chlorides of 2-phenoxy carboxylic acids (2-phenoxypropionic, 2-phenoxyisovaleric, and 2-phenoxy-3-phenylpropionic) in toluene and dichloromethane at different temperatures. HPLC analysis of the acylation products showed the predominant formation of ( R ∗ , S ∗ )-diastereoisomeric amides in all cases. It was found that acylation with the studied acyl chlorides was highly stereoselective; 2-phenoxyisovaleryl chloride demonstrated the highest stereoselectivity (selectivity factor s up to 499). A model for the diastereoisomeric transition states in the interaction between racemic amine and acyl chloride is proposed. [ABSTRACT FROM AUTHOR]

2-(Trifluoroacetyl)chromones were obtained in good yields via the Claisen condensation of 2-hydroxyacetophenones with methyl 2-methoxytetrafluoropropionate, followed by sulfuric acid-mediated deprotection of the reaction products. These compounds react with ethylenediamine in the presence of acetic acid in methanol to produce the target 2-salicyloylmethylene-3-(trifluoromethyl)-1,2,5,6-tetrahydropyrazines in 48–61% yield. In a similar manner, their reactions with o -phenylenediamine and 2,3-diaminonaphthaline in refluxing acetic acid gave a mixture of ketoenamine and ketoimine tautomers of the corresponding quinoxaline derivatives in excellent yields. The regioisomeric and tautomeric composition of the pyrido[2,3- b ]pyrazines prepared from 2-(trifluoroacetyl)chromones and 2,3-diaminopyridine was also investigated. [ABSTRACT FROM AUTHOR]

1,2-Epoxyperfluorocyclohexane reacts with 3,3’,4,4’-tetraaminobiphenyl (1 : 1 mol / mol) to give 4-(6,6,7,7,8,8,9,9-octafluoro- 6,7,8,9-tetrahydrophenazin-2-yl)benzene-1,2-diamine whose structure was determined by X-ray crystallography. Reactions of the latter with 1,2-epoxyperfluorocyclohexane or benzil bring about new fluorinated phenazine derivatives. [ABSTRACT FROM AUTHOR]

It has been found that acyl chlorides of ( S )-naproxen, N -phthaloyl-( S )-leucine, and N -tosyl-( S )-proline are efficient chiral resolving agents for the acylative kinetic resolution of racemic 3-methyl- and 3-phenyl-3,4-dihydro-3-methyl-2 H -[1,4]benzothiazines. Based on the experimental results, a preparative protocol comprising the acylative kinetic resolution followed by isolation of a single (major) diastereoisomeric amide and subsequent hydrolysis of amide bond was proposed. Using this approach with various chiral resolving agents, ( S )- and ( R )-enantiomers of 3,4-dihydro-3-methyl-2 H -[1,4]benzothiazine (ee >99%) were obtained. The oxidation of the corresponding diastereoisomers of the amides followed by deacylation led to the ( S )- and ( R )-enantiomers of 3,4-dihydro-3-methyl-2 H -[1,4]benzothiazine-1,1-dioxide (ee >97%). This method proved to be less suitable for the preparation of the ( S )-enantiomer of 3,4-dihydro-3-phenyl-2 H -[1,4]benzothiazine (ee up to 93%) and its sulfone (ee 82%) which were both obtained in low yields. The loss of enantioselectivity for ( S )-3,4-dihydro-3-phenyl-2 H -[1,4]benzothiazine and its sulfone occurred during hydrolysis of the corresponding diastereoisomerically pure amides. [ABSTRACT FROM AUTHOR]

Abstract: 3-Nitro-2-trichloro(trifluoro)methyl-2H-chromenes undergo a formal [4+2] cycloaddition reaction to cyclohexanone and pinacolone enamines, producing chromeno[3,4-c][1,2]benzoxazin-6-oxides with high diastereoselectivity and in good yields. In addition, some novel 2,3,4-trisubstituted chromanes were obtained. The stereochemistry of the products was established based on a 2D NOESY experiment and an X-ray diffraction study. [Copyright &y& Elsevier]

Abstract: The acylative kinetic resolution of racemic 6-fluoro-2-methyl-1,2,3,4-tetrahydroquinoline, 7,8-difluoro-3,4-dihydro-3-methyl-2H-[1,4]benzoxazine, and their non-fluorinated analogues with (S)-naproxen and N-phthaloyl-(S)-amino acyl chlorides has been carried out. It has been shown that the presence of fluorine atoms in the aromatic fragment of a heterocyclic amine results in the increasing stereoselectivity of acylation with (S)-naproxen acyl chloride and in a decrease in the efficiency of acylative kinetic resolution using N-phthaloyl-(S)-amino acyl chlorides. A method for the preparation of enantiopure (S)-6-fluoro-2-methyl-1,2,3,4-tetrahydroquinoline (ee >99%) was developed. [Copyright &y& Elsevier]

Abstract: Reactions of 3-nitro-2-trifluoro(trichloro)methyl-2H-chromenes, including 2-unsubstituted derivatives, with N-alkyl-α-amino acids (sarcosine, proline) and paraformaldehyde proceed diastereoselectively to give 1-benzopyrano[3,4-c]pyrrolidines in good yields as a result of a 1,3-dipolar cycloaddition of the intermediate nonstabilized azomethine ylide at the Δ3-bond of the chromene system. [Copyright &y& Elsevier]

Abstract: 5-Bromopyrimidine reacts with 2,2′-bithiophene, [2,2′:5′,2″]terthiophene and 2-phenylthiophene in the presence of a palladium catalyst to give 5-(het)aryl substituted pyrimidines due to the palladium-catalyzed aryl–aryl C–C coupling. However 5-bromo-4-(het)aryl-pyrimidines have been prepared from the same starting materials through the SN H-reaction catalyzed by a Lewis acid. Conditions for both types of reactions were optimized. All components of the reaction mixtures, including by-products, have been elucidated by gas–liquid chromatography/mass-spectrometry. Evidence for the structure of 4- and 5-bithiophenyl-substituted pyrimidines has first been obtained by means of X-ray crystallography analysis. Molecular orbital calculations (TDDFT), as well as the redox and optical measurements for all new compounds have also been performed. [Copyright &y& Elsevier]

Abstract: Pyridoxal undergoes oxa-Michael initiated ring closure with 2-(trifluoromethyl)chromones giving 11a,13-dihydro-6H-1-benzopyrano[3′,2′:6,7]oxepino[3,4-c]pyridin-6-ones and 6H,11aH-1-benzopyrano[3′,2′:5,6]pyrano[2,3-c]pyridin-6-ones. Participation of alcoholic hydroxy group of pyridoxal in the initial oxa-Michael addition leads to the former product and that of the phenyl hydroxy group to the later one. [Copyright &y& Elsevier]

Abstract: It has been shown that combination of the Suzuki–Miyaura cross-coupling and nucleophilic aromatic substitution of hydrogen is a versatile method for the synthesis of 4-(thiophen-2-yl)-, 5-(thiophen-2-yl)-, and 4,5-di(thiophen-2-yl) substituted pyrimidines from the commercially available 5-bromopyrimidine. The (AE)- and (AO)-reactions of 5-bromopyrimidine with thiophene and 2-bromothiophene have been studied by gas–liquid chromatography/mass-spectrometry. The structures of intermediate σH-adducts, as well as thiophene-(thiophenyl)pyrimidine and bithiophene-(thiophenyl)pyrimidine dyads have first been established by X-ray crystallography analysis. [Copyright &y& Elsevier]

Abstract: The acylative kinetic resolution of racemic 2-methyl-1,2,3,4-tetrahydroquinoline and 2,3-dihydro-3-methyl-4H-1,4-benzoxazine using acyl chlorides of N-phthaloyl-(S)-phenylalanine, N-phthaloyl-3-(4-nitrophenyl)-(S)-alanine and N-phthaloyl-O-methyl-(S)-tyrosine as chiral resolving agents has been carried out. It is shown that the effectiveness of an acylative kinetic resolution depends on the electronic effects of substituents in the phenyl fragment of the acylating agent and increases as the electron-donating properties of the para-substituent (OMe>H>NO2) in phenyl fragment of N-phthaloyl-3-aryl-(S)-alanyl chlorides increase; conducting the process at a reduced temperature also contributes to an enhancement of the kinetic resolution. [Copyright &y& Elsevier]

Abstract: A comparative study of the kinetic resolution of racemic 2-methyl-1,2,3,4-tetrahydroquinoline and 2,3-dihydro-3-methyl-4H-1,4-benzoxazine using N-phthaloyl-(S)-amino acyl chlorides as chiral acylating agents is described. Temperature and solvent effects on the stereochemical features have been examined. It has been found that N-phthaloyl-(S)-phenylalanyl and N-phthaloyl-(S)-2-phenylglycyl chlorides bearing aromatic substituents close to the stereogenic centre are more stereoselective acylating agents than N-phthaloyl-(S)-alanyl chloride. For the preparative kinetic resolution of racemic amines N-phthaloyl-(S)-phenylalanyl chloride proved to be the most appropriate chiral acylating agent. [Copyright &y& Elsevier]

Reaction of 3-aryl-1,2,4-triazines with S,N-dinucleophilic N -(het)arylthioureas in acetic anhydride at room temperature affords the cyclization products, tetrahydrothiazolo[4,5- e ]-[1,2,4]triazines in good yields. The structure of the heterocyclic system thus formed was confirmed by X-ray diffraction analysis. [ABSTRACT FROM AUTHOR]

Abstract: The reaction of oxides of internal perfluoroolefins 1–3 with urea gave two kinds of novel fluorine containing N-heterocyclic compounds depending on the solvent nature: 1,5-bis(perfluoroalkyl)tetraazabicyclo[3.3.0]octane-3,7-diones 4a–c and 2-amino-5-fluoro-4,5-bis(perfluoroalkyl)-4,5-dihydrooxazol-4-ols 7a–d. Use of polar dimethylsulfoxide, N,N-dimethylacetamide and acetonitrile afforded glycolurils 4a–c in moderate yields. In dioxane, unexpected cyclization occurred resulting in oxazolines 7a–d in high yields. A similar reaction of oxiranes 2, 3 with urea in aqueous dioxane gave mixtures of 4,5-dihydroxy-4,5-bis(perfluoroalkyl)imidazolidine-2-ones 9b, c, glycolurils 4b, c and oxazolines 7b–d. The molecular structure of trans-isomers of oxazoline 7b and imidazolidine 9b has been established by X-ray crystallography. [Copyright &y& Elsevier]

Abstract: Reaction of 3-alkylsulfanyl-2-arylazo-3-(pyrrolidin-1-yl)acrylonitriles with maleimides, dimethyl maleate and dimethylacetylene dicarboxylate were carried out to give octahydro-pyrrolo[3,4-a]pyrrolizin-4-ylidenes, hexahydro-pyrrolizines and 6,7-dihydro-5H-pyrrolizines. The formation of the synthesized compounds is explained by a 1,3-dipolar cycloaddition of an in situ generated azomethine ylide. The mechanisms of the formation of these active intermediates were discussed with the aid of density functional theory methods with the B3LYP functional 6-31G+ calculations using the STQN method and chemical experiments. [Copyright &y& Elsevier]

Efficient methods for the incorporation of 15N-isotope into 1,2,4-triazolo[5,1-c][1,2,4]triazines have been developed. The label can be selectively introduced into either the azolo or azine fragment of the molecule. [ABSTRACT FROM AUTHOR]

Abstract: The reactions of oxides of internal trans-, cis-perfluoroolefins with o-phenylenediamine and 2-aminophenol in dioxane gave 2,3-bis(perfluoroalkyl)quinoxalines and 2,3-bis(perfluoroalkyl)-2H-1,4-benzoxazin-2-ols respectively in yields of 23–67%. When N,N-dimethylacetamide was used as a solvent an anionic isomerization of the oxides into ketones, which further yielded 2-(perfluoroalkyl)benzimidazoles in the case of o-phenylenediamine and 2-hydroxy-N-perfluoroalkanoylanilines in the case of 2-aminophenol, became the main path of these reactions. Unusual cyclization resulting in 2-pentafluoroethyl-2-pentafluoropropanoylbenzoxazolidine occurs on interaction between dodecafluoro-3,4-epoxyhexane and 2-aminophenol in N,N-dimethylacetamide. [Copyright &y& Elsevier]

6-Amino-4-trifluoromethyl-5,6-dihydro-4H-1,2-oxazine 2-oxides undergo spontaneous rearrangement into 4-amino-2-hydroxy-4-trifluoromethyl-3,4-dihydro-2H-pyrrole 1-oxides. [Copyright &y& Elsevier]

Reactions of (E)-1,1,1-trichloro(trifluoro)-3-nitrobut-2-enes with 3,3-dimethyl-2-morpholinobutene in benzene give (4R*,6R*)-6-tert-butyl-3-methyl-6-morpholino-4-trihalomethyl-5,6-dihydro-4H-1,2-oxazine 2-oxides. In a dichloromethane solution, these cyclic nitronates undergo diastereoselective ring opening to produce nitroalkylated anti-CCl3- and syn-CF3-enamines, which are hydrolysed with dilute HCl to afford the respective anti-CCl3- and syn-CF3-g-nitroketones. [ABSTRACT FROM AUTHOR]

The first example of the domino hetero-Diels–Alder/1,3-dipolar cycloaddition, in which 3,3,3-trichloro(trifluoro)-1-nitropropenes act as both the heterodiene and the dipolarophile in the reaction with 2,3-dihydrofuran, is described. The trichloromethylated nitroolefin gave tricyclic nitroso acetal as a single regio- and stereoisomer, while the trifluoromethylated derivative afforded a 3:1 mixture of two regioisomeric cycloadducts. [Copyright &y& Elsevier]

• New approaches to polyfluoroalkylated pyrido[1,2- a ]pyrimidinones, pyrido[2,1- b ]quinazolinones and bis -cyclohexenones were developed. • One-pot method based on commercially available reagents. • Reactions are carried out under mild conditions • Some synthesized heterocycles showed moderate antiviral activity. A one-pot three-component reactions between polyfluoroalkylated 3-oxo esters and methyl ketones with 1,3-diaminopropane result in 8-hydroxy-9a-alkyl(phenyl)-8-(polyfluoroalkyl)octahydro-6H-pyrido[1,2-a]pyrimidin-6-ones, whereas a similar reaction with 1,4-diaminobutane forms a salt with trifluoroacetoacetic ester. In a two-component reaction, diamines with a long aliphatic chain (1,4-diaminobutane, 1,6-diaminohexane and 1,8-diaminooctane) react with an aldol derived from trifluoroacetoacetic ester and acetone, to give bis-cyclohexenones having an aliphatic linker. Using 2-(aminomethyl)aniline in a three-component reaction with polyfluoroalkyl-3-oxo esters leads to new 7-hydroxy-5a-alkyl(phenyl)-7-(polyfluoroalkyl)-5a,6,7,8-tetrahydro-5H-pyrido[2,1-b]quinazolin-9(11H)-ones. Regioisomeric and spatial structures of new heterocycles were studied, and the mechanism of their formation was proposed. Some synthesized heterocycles were found to have moderate antiviral activity against influenza A/Puerto Rico/8/34 (H1N1) and Coxsackie B3 viruses. [ABSTRACT FROM AUTHOR]

The enantiomers of 3-amino-1-methyl-1,2-dicarba-closo-dodecaborane were prepared by means of resolution of the racemic mixture via acylation by (S)-naproxen chloride followed by separation and subsequent acid hydrolysis of each of the diastereoisomeric amides. Partial racemization of enantiomeric 3-aminocarboranes was observed during acid hydrolysis. [Copyright &y& Elsevier]

Graphical abstract The reaction between equimolar amounts of 3,4-epoxyperfluorooxolane and 3,3′,4,4′-tetraaminobiphenyl provided a new fluorine-containing diamino derivative of furoquinoxaline, namely, 6-(3,4-diaminophenyl)-1,1,3,3-tetrafluoro-1,3-dihydro-furo[3,4- b ]quinoxaline. Its reactions with 3,4-epoxyperfluorooxolane, 1,2-diphenylethanedione, or di(2-thienyl)ethanedione yielded new quinoxaline fluorine-containing polycyclic compounds whose structures were confirmed by X-ray diffraction. [ABSTRACT FROM AUTHOR]

6-Amino-1,3-dimethyluracil reacts with two molecules of alkanals (butanal or pentanal) in formic acid to give 1,3,7,9-tetramethyl- 2,4,6,8-tetraoxopyrido[2,3- d ][6,5- d’ ]dipyrimidine and the corresponding 3,4-dialkyl-substituted 6,8-dimethyl-5,7-dioxopyrido[2,3- d ]- pyrimidines. [ABSTRACT FROM AUTHOR]

Depending on conditions, reaction of 3-amino-4H-chromeno[3,4-d]isoxazol-4-one with benzoyl chloride gives 4-hydroxy- and/or 4-benzoyloxy-3-(5-phenyl-1,2,4-oxadiazol-3-yl)coumarins, which are rearranged into 2-benzamido-4H-chromeno[3,4-d]oxazol-4-one by heating in DMSO. [ABSTRACT FROM AUTHOR]

An abstract of the article "Synthesis of 4-Arylamino-3-(trifluoromethyl)pyridazines and Pyridazino[3,4-b]quinoxalines (as By-Products) from 3-Aroylmethyl-2-(trifluoromethyl)quinoxalines and Hydrazine Hydrate," by V. Y. Sosnovskikh and colleagues is presented.

The diastereoselectivity of the title addition depends on the reaction temperature. [ABSTRACT FROM AUTHOR]

Amino acids with unusual types of chirality and their derivatives have recently attracted attention as precursors in the synthesis of chiral catalysts and peptide analogues with unique properties. In this study, we have synthesized a new nido -carborane-based planar-chiral amino acid, in the molecule of which the amino group is directly bonded to the B(3) atom, and the carboxyl group is attached to the B(9) atom through the CH 2 S + (Me) fragment. 3-Amino-9-dimethylsulfonio- nido -carborane, prepared in three steps from 3-amino- closo -carborane in a high yield, was a key intermediate in the synthesis of the target planar-chiral amino acid. The carboxymethyl group at the sulfur atom was introduced by the demethylation reaction of the dimethylsulfonio derivative, followed by S-alkylation. The structure of new 3,9-disubstituted nido -carboranes was studied for the first time using NMR spectroscopy. The resonances of all boron atoms in the 11 B NMR spectrum of 3-amino-9-dimethylsulfonio- nido -carborane were assigned based on the 2D NMR correlation experiments. The nido -carborane-based planar-chiral amino acid and related compounds are of interest as a basis for peptide-like compounds and chiral ligands.

Venous thromboembolism is a serious problem because it significantly increases the risk of developing vascular complications in elderly patients with obesity or immobilization, cancer, and many other diseases. Thus, there is a need to study new therapeutic strategies, including new medicinal agents for the efficient and safe correction of thrombus disorders. In this work, we have synthesized a number of new amides and peptides of 4-amino-5-oxoprolines and studied their antiplatelet and antithrombotic activity in experiments in vitro and in vivo. It has been found that the newly obtained compounds slow down the process of thrombus formation in a model of arterial and venous thrombosis, without affecting plasma hemostasis parameters. (2 S ,4 S )-4-Amino-1-(4-fluorophenyl)-5-oxoprolyl-( S )-phenylalanine proved to be the most efficient among the studied derivatives. The results obtained indicate the advisability of further studies on 5-oxoproline derivatives in order to design pharmaceutical agents for the prevention and treatment of the consequences of thrombosis.

A new group of charge-compensated nido -carboranyl derivatives of sulfur-containing amino acids and biotin has been synthesized in which the boron atom in position 9 or 10 of carborane is attached to a positively charged sulfur atom. The possibilities of obtaining symmetrical B(10)-substituted and asymmetric B(9)-substituted nido -carboranes were studied. Using the example of ( S )-methionine and D-biotin derivatives, water-soluble S-substituted charge-compensated nido -carboranes with free functional groups were prepared. The results obtained open up prospects for the development of potential boron delivery agents for BNCT as well as new bioactive compounds containing a negatively charged nido -carboranyl fragment bearing a positive charge on the sulfur atom associated with the boron cluster.

The diastereoselective acylation of a number of racemic methyl-substituted cyclic alkylamines with active esters of 2-phenoxypropanoic acid was studied in detail. The ester of ( R )-2-phenoxypropanoic acid and N -hydroxysuccinimide was found to be the most selective agent. The highest stereoselectivity was observed in the kinetic resolution of racemic 2-methylpiperidine in toluene at -40 °C (selectivity factor s = 73) with the predominant formation of ( R , R )-amide (93.7% de ). To explain the observed stereoselectivity, DFT modelling of the transition states in the reactions of the title acylating agent with 2-methylpiperidine and 2-methylpyrrolidine was performed. The calculated values were in good agreement with experimental data. It has been demonstrated that the acylation proceeds via a concerted mechanism, in which the addition of an amine occurs simultaneously with the elimination of the hydroxysuccinimide fragment. The high stereoselectivity of the ( R , R )-amide formation is largely ensured by the lower steric hindrances in the transition states as compared to the formation of ( R , S )-amide.

Heteroanalogs of ascidian alkaloids have been synthesized, and for the first time 10 different types of saturated carbo- and heteroannulated pyridones have been obtained. A new method for the formation of decahydro[1,3]oxazolo[2,3- j ]quinoline and octahydro-5 H -cyclopenta[ b ][1,3]oxazolo[3,2- a ]pyridine was proposed. The synthesis of these heterocycles is based on the three-component cyclization of trifluoroacetoacetic ester and cycloketones with 1,2- and 1,3-dinucleophiles. It was found that reactions with amino alcohols are distinguished by the possibility of isolating carbocyclopyridones of various degrees of saturation. The diastereomeric structure of the synthesized heterocycles has been studied, and the mechanism of their formation has been proposed. Antitumor, anti-influenza and analgesic agents have been found among the synthesized compounds.

A new one-pot reaction between polyfluoroalkylated 3-oxo esters, methyl ketones and primary or secondary alkyl amines is reported as an efficient approach to 3-alkylamino-5-hydroxy-5-polyfluoroalkylcyclohex-2-en-1-ones. The scope of three-component cyclization and its plausible mechanism are discussed. The described protocol makes it possible to vary the functional substituents in 2, 3 and 5 positions of carbocycles. Anhydrous conditions are necessary for the productive synthesis of aminocyclohexenones, whereas in the presence of water the competitive formation of alkyl ammonium salts of keto hydroxy carboxylates is observed. Dehydration of the aminocyclohexenones was effectively used for the synthesis of 3-alkylamino-5-trifluoromethylphenols, some of which exhibited moderate antifungal activities against eight pathogenic fungal strains.

A method of synthesis of chitosan imidazolyl derivative - N-(5-methyl-4-imidazolyl)methylchitosan (IM-chitosan) with high degree of substitution (DS) via reaction with 5-methyl-4-imidazolylmethanol has been developed. This method enables one to obtain polymers with the DS up to 1.35 with simultaneous cross-linkage of the matrix. The chemical structure of the obtained IM-chitosan was characterized by FT-IR, (13)C and (15)N NMR spectroscopies. It was shown that cross-linkage of IM-chitosans occurred due to formation of N-glucoside derivatives. Sorption capacities of IM-chitosans toward transition metal ions have an extremal dependence on DS, which is less pronounced for Ag(I) ions in comparison with Cu(II) and Ni(II) ions. The decrease of sorption capacities for derivatives with DS 0.5-1.0 is attributed to steric hindrances for ion-binding due to increased stiffness of the polymer matrix at high DS as a result of cross-linking. Sorption capacities of IM-chitosans toward noble metal ions in 0.1M HCl gradually increase with DS, since higher swelling polymers in acidic media eliminates negative effect of cross-linking on availability of sorption sites., (Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.)