M. I. Kodess

Kinetic resolution of (′)-2,3-dihydro-3-methyl-4H-1,4-benzoxazine, (′) -2-methyl-1,2,3,4-tetrahydroquinoline and (′)-2-methylindoline using N-tosyl-(S)-prolyl chloride

Acylation of racemic 2,3-dihydro-3-methyl-4H-1,4-benzoxazine, 2-methyl-1,2,3,4-tetrahydroquinoline and 2-methylindoline with N-tosyl-(S)-prolyl chloride resulted in their kinetic resolution with the predominant formation of (R,S)-diastereoisomeric amides, des being 80, 66 and 38%, respectively. Recrystallisation of the amides followed by acid hydrolysis gave individual (R)-enantiomers of heterocyclic amines.

Synthesis of 7-Alkyl(aryl)-6-alkoxycarbonyl-5-fluoroalkyl-1,2,4-tri(tetr)azolo[1,5-a]pyrimidines

Fluorinated 3-oxo esters react with aldehydes and 3-amino-1,2,4-triazoles and 5-aminotetrazoles to give, respectively, 7-alkyl(aryl)-6-alkoxycarbonyl-5-fluoroalkyl-1,2,4-triazolo[1,5-a]pyrimidines and -tetra-zolo[1,5-a]pyrimidines. The same heterocyclic products can be obtained by reaction of 2-benzylidene-2-fluoroacyl esters with the corresponding aminoazoles.

Synthesis in a gel and sorption properties of N-2-sulfoethyl chitosan

A new procedure was developed for preparation of chelate amino-containing polymer N-2-sulfoethyl chitosan by synthesis in a gel through the reaction between chitosan and sodium 2-bromoethanesulfonate, yielding a polymer with the degree of substitution of up to 0.5. The structure of the resulting polymers was confirmed by 1H NMR spectroscopy. The sorption characteristics with respect to transition and alkaline-earth metal ions were determined for the cross-linked polymers.

Reactions of 3-nitro-2-trihalomethyl-2H-chromenes with S- and N-nucleophiles. Synthesis and stereochemistry of 2,3,4-trisubstituted chromanes

The reactions of 3-nitro-2-trifluoromethyl-and 3-nitro-2-trichloromethyl-2H-chromenes with thiols and aromatic amines proceed via the nucleophilic addition type to the activated double bond to form 2,3,4-trisubstituted chromanes in high yields. The stereoisomeric compositions and structures of the diastereomers were determined by 1H, 19F NMR and 2D NOESY spectroscopies and X-ray diffraction analysis.

Fluorine-containing heterocycles: XII. fluorine-containing quinazolin-4-ones and azolo[a]quinazolinone derivatives

Methods for the synthesis of fluorine-containing derivatives of 2-imino-1,3-diphenylquinazolin-4-one, imidazo[1,2-a]quinazolin-5-one, pyrazolo[1,5-a]quinazolin-5-one, and [1,2,4]triazolo[1,5-a]quinazolin-5-one were developed on the basis of the reaction of tetrafluorobenzoyl chloride with N,N′-diphenylguanidine and aminoazoles.

Synthesis of polyfluoroalkylated 1,4-diazinols and 1,4-oxazinols using polyfluoro-2,3-epoxyalkanes32 + 13

Abstract It has been found that the reactions of polyfluoro-2,3-epoxyalkanes with ethylenediamine and 2-aminoethanol yield 2,3-di(polyfluoroalkyl) 1,5,6-trihydro-1,4-diazin-2-ols and 2,3-di(polyfluoroalkyl) -5,6-dihydro-1,4-oxazin-2-ols, respectively. In the case of unsymmetrical oxiranes mixtures of regioisomeric heterocyclic compounds have been obtained. These reactions were found to give some byproducts—N,N′-bis (polyfluoroacyl)ethylenediamines and N-polyfluoroacyl-2-aminoethanols.

Aminovinyl ketones and aminovinyl esters as CCN building blocks for the synthesis of 1H-pyrrolo[3,2-e]1,2,4-triazines

5,6-Unsubstituted-3-aryl-1,2,4-triazines were found to react with aminovinyl ketones and aminovinyl esters in acetic anhydride to form derivatives of 3a,4,7,7a-tetrahydro-1H-pyrrolo[3,2-e]1,2,4-triazines in good yields.

Enantiomers of 3-amino-1-methyl-1,2-dicarba-closo-dodecaborane

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.

Reactions of 3-nitro-2-trihalomethyl-2H-chromenes with C-nucleophiles. Synthesis of 3-nitro-4-(pyrazol-4-yl)-2-trihalomethylchromanes

The nucleophilic addition of acetylacetone and ethyl acetoacetate at the double bond of 3-nitro-2-trihalomethyl-2H-chromenes in the presence of NaH affords 2,3,4-trisubstituted chromanes containing the β-dicarbonyl fragment at position 4. The trans-trans configuration and the enol structure of the reaction products were confirmed by 1H NMR spectroscopy and X-ray diffraction. Treatment of these compounds with hydrazine gives the corresponding 3-nitro-4-(pyrazol-4-yl)-2-trihalomethylchromanes. The reactions of 3-nitro-2-trihalomethyl-2H-chromenes with nitromethane and nitroethane in the presence of K2CO3 produce 1,3-dinitro derivatives of the chromane series.

Carboxyalkylation of chitosan in the gel state.

This study presents a new approach for direct carboxyalkylation of chitosan in the gel state by using aza-Michael addition and substitution reactions. Various reagents were applied including acrylic and crotonic acids, and α-, β-, γ-, δ-, and ɛ-halocarboxylic acids. The reaction of chitosan with γ- and δ-halocarboxylic acids showed no target product formation either in solution or in the gel state. In the case of acrylic, crotonic, α- and β-halocarboxylic acids, the reaction performed in the gel state (concentration of chitosan 20-40%) shows higher degree of substitution at lower reaction time and temperature than in diluted solutions (concentration of chitosan 0.5-2%). The results were discussed in terms of kinetics of the target and side reactions. (1)H and (13)C NMR confirmed that in all cases the carboxyalkylation of chitosan proceeds exclusively at the amino groups.