Synthesis of ammonium salts ofO-substitutedN-nitrohydroxylamines

Ammonium salts ofO-substitutedN-nitrohydroxylamines were synthesized by nitration ofO-substitutedN-benzoyl- orp-nitrobenzoy1hydroxylamines followed by treatment of the reaction products with an alcohol solution of ammonia.Translated fromIzvestiya Akadernii Nauk. Seriya Khimicheskaya, No. 1, pp. 132–134, January, 1996.     

Synthesis of 2,3,4,6-tetra-O-acetyl-β-D-gluco(galacto)pyranosylcaprolactams and 2,3,4,6-tetra-O-acetyl-β-D-gluco(galacto) pyranosylpyrrolidones

A new synthesis of certain lactam-containing N-glycosides was developed. 2,3,4,6-Tetra-O-acetyl-β-D-gluco(galacto)pyranosylcaprolactams and 2,3,4,6-tetra-O-acetyl-β-D-gluco(galacto)pyranosylpyrrolidones were synthesized by condensation at room temperature of acetobromoglucose and acetobromogalactose with ɛ-caprolactams and α-pyrrolidone. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 105–106, March–April, 2006.     

X-ray Crystal and Ab Initio Structures of 3′,5′-di-O-Acetyl-N(4)-Hydroxy-2′-Deoxycytidine and Its 5-Fluoro Analogue: Models of the N(4)-OH-dCMP and N(4)-OH-FdCMP Molecules Interacting with Thymidylate Synthase

The crystal and molecular structures of the 3′,5′-di-O-acetyl-N(4)-hydroxy-2′-deoxycytidine molecule and its 5-fluoro congener have been determined by X-ray single crystal diffraction. The 3′,5′-di-O-acetyl-N(4)-hydroxy-5-fluoro-2′-deoxycytidine molecule crystallizes in the space group C2 with the following unit cell parameters: a = 21.72 Å, b = 8.72 Å, c = 8.61 Å, and β = 90.42^∘. 3′,5′-di-O-acetyl-N(4)-hydroxy-2′-deoxycytidine also belongs to the monoclinic space group C2 and the unit cell parameters are: a = 39.54 Å, b = 8.72 Å, c = 22.89 Å, and β = 95.26^∘. The non-fluorine analogue demonstrates a rare example of crystal structure with five symmetry-independent molecules in the unit cell. All the molecules in both crystal structures have the sugar residue anti oriented with respect to the base, as well as have the N(4)-OH residue in cis conformation relatively to the N(3)-nitrogen atom. In addition to the molecular geometries from X-ray experiment, the optimized molecular geometries have been obtained with the use of theoretical ab initio calculations at the RHF/6-31G(d) level. The corresponding geometric parameters in the molecules of 3′,5′-di-O-acetyl-N(4)-hydroxy-2′-deoxycytidine and its 5-fluoro congener have been compared. The differences including the C(5)=C(6) bond shortening and C(4)—C(5)—C(6) angle widening in the fluorine analogue are discussed in this paper in relation to the molecular mechanism of enzyme, thymidylate synthase, inhibition by N(4)-hydroxy-2′-deoxycytidine monophosphate and its 5-fluoro congener.     

Catalytic silylotropy inN-trimethylsilylpyrazole derivatives

Silylotropy in 4-substitutedN-trimethylsilypyrazoles is studied by dynamic¹H,¹³C, and²⁹Si NMR spectroscopy. The catalytic 1,2-migration of a trimethylsilyl group in 4-halo-N-trimethylsilylpyrazoles was detected. Silylotropy inN-trimethylsilylpyrazoles in the presence of halogens of trimethylhalosilanes is believed to proceed through formation ofN,N-bis(trimethylsilyl)pyrazolium salts, the barrier of silylotropy in pyrazoles being markedly reduced.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 3011–3013, December, 1996.     

Formation and thermal decomposition of adducts of phthalimidonitrene with spiro(1-pyrazolinecyclopropanes)

Oxidation ofN-aminophthalimide with lead tetraacetate in the presence of spiro(1-pyrazolinecyclopropanes) at temperature from −20°C to −30°C resulted in the formal generation of phthalimidonitrene followed by its addition at the N=N bond of the pyrazoline ring to form 5(3)-substitutedN-{spiro[1-pyrazolinio-3(5),1′-cyclopropane]}-N-phthalimidoamides (azimines), whose regioisomeric compositions were determined to a large extent by the nature of the substituents in the pyrazoline ring. The structures of phthalimidoazimines were established based on the NMR spectra and X-ray diffraction data. Thermal conversions of the resulting adducts, which proceeded either with retention or with opening of the spiro-fused cyclopropane ring, were studied. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1328–1333, July, 1999.     

The evidence for complex formation between N-acetyl-l-tyrosine methyl ester and N-acetylprocainamide hydrochloride using NMR spectroscopy

In order to reveal the possible mechanism of the recognition of antiarrhythmic agents class I and class III by the amino acid residues, which are responsible for drug binding to the selectivity filters either in the sodium or potassium ion channels, co-crystallizations of procainamide hydrochloride and N-acetylprocainamide hydrochloride with N-acetyl-l-tyrosine methyl ester and N-acetyl-l-phenylalanine methyl ester were performed using various conditions. Because the crystallization of the complexes failed, the intermolecular interactions between the components were evidenced using NMR spectroscopy. Exclusively, in the case of N-acetylprocainamide hydrochloride and N-acetyl-l-tyrosine methyl ester, two-dimensional NMR experiments and Job Plot analysis indicated the formation of the 1:1 complex in DMSO-d ₆  solution (with the association constant of 16 M⁻¹), whereas for the mixture of procainamide hydrochloride with N-acetyl-l-tyrosine methyl ester, the complex formation was not confirmed. The NMR results were discussed using crystal structure data obtained for N-acetylprocainamide hydrochloride, procainamide hydrochloride, as well as procainamide dihydrochloride, and were compared with the known pharmacological activity of the antiarrhythmic agents.     

Phosphorylation ofN-trimethylsilyllactams

Treatment ofN-trimethylsilyllactams with phosphoryl chlorides results in mixtures of products, whose formation can be explained by competition betweenN- andO-phosphorylation.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1644–1648, September, 1994.     

<Emphasis Type="Italic">N</Emphasis>-Bromoacetyl-β-<Emphasis Type="SmallCaps">D</Emphasis>-glycopyranosylamines in the synthesis of glycoconjugates of nitrogen-containing physiologically active compounds

A series of nitrogen-containing physiologically active compounds underwent smooth N-monoalkylation with N-bromoacetyl-β-glycopyranosylamines derived from N-acetyl-D-glucosamine and lactose. This reaction was demonstrated to be promising for the introduction of carbohydrate residues into heterocyclic compounds, viz., pyridine, imidazole, pyrimidinetrione, carboline, and piperazine derivatives, and into an amino acid, 5-hydroxy-L-tryptophan, which is unstable in alkaline media. Dedicated to Academician N. K. Kochetkov on the occasion of his 90th birthday. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1256–1259, May, 2005.     

N-glycyl-β-glycopyranosylamines, derivatives of mono- and disaccharides, and their use for the preparation of carboxylic acid glycoconjugates

A convenient preparative procedure was developed for the synthesis ofN-glycyl-β-glycopyranosylamines, derivatives of monosaccharides (d-galactose,d-mannose,l-fucose, andN-acetyl-d-glucosamine) and disaccharides (lactose, melibiose, cellobiose, and maltose). These compounds were demonstrated to be useful for the preparation of glycoconjugates of biologically active compounds containing the carboxy group (nicotinic, orotic, kynurenic, and indoleacetic acids). Synthetic pathways were developed for conversions ofN-glycyl-β-glycopyranosylamines into derivatives containing the carboxy group with the use of malonic andl-tartaric acid derivatives. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1461–1466, August, 2000.     

An Efficient Method for the Synthesis of N-Acylsulfonamides: One-pot Sulfonylation and Acylation of Primary Arylamines under Solvent-Free Conditions

Summary. The preparation of N-acylsulfonamides is described using primary amines, arylsulfonyl chlorides and acyl chlorides. Reaction of primary aryl amines with arylsulfonyl chlorides in the presence of NaHCO₃ produced N-arylsulfonamides, which reacted in situ with benzoyl chloride furnishing the corresponding N-benzoyl-N-arylsulfonamides in 72–96% yields. Accordingly, 4-nitrobenzoyl chloride and 3,5-dinitrobenzoyl chloride were used as acylating agents. All the reactions were carried out under solvent-free conditions at room temperature and the products were isolated after simple work-up in high yields and purity.     

Complexation equilibrium in a substrate- MgCl2(CaCl2)-Pd/C catalytic system and the influence of its position on asymmetric induction in hydrogenation ofN-acetyl-dehydrophenylalanyl-S-proline

The role of Ca and Mg salts as promoters of asymmetric induction in hydrogenation ofN-acetyl-dehydrophenylalanyl-S-proline in a substrate— MX₂—Pd/C catalytic system was studied. The data of potentiometric titration,¹H NMR spectroscopy, and the value of diastereomeric excess (de) of the resultingN-acetyl-R-phenylalanyl-S-proline indicate the complexation of the substrate with calcium and magnesium chlorides in an alcoholic solution. Ionization and equilibrium constants of the complex were determined. Excess salt shifts the equilibrium toward the complex formation, which increasesde up to 70 %.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1964–1967, August, 1996.     

Reactions of hexaorganyldigermoxanes with O-trimethylsilyl carbamates

Hexa-n-butyl- and hexaisopentyldigermoxanes but not hexaphenyldigermoxane react with O-trimethylsilyl N,N-diethylcarbamate and trimethylsilyl piperidinocarboxylate to give O-triorganylgermyl carbamates.     

Reactions of 3-hydroxytetrahydropyrimidin-4-ones with electrophilic reagents

The reactions of nonsubstituted or 2-aryl-substituted 3-hydroxytetrahydropyrimidin-4-ones (HTHP) with carboxylic acid chlorides, tosyl chloride, or aryl isocyanates afford mainlyN,O-diacylated,N,O-ditosylated, orN,O-diarylcarbamoylated HTHP, respectively.N,O-Diacylated HTHP are also formed in the reactions of acid chlorides with Schiff's bases based on β-aminopropionohydroxamic acid.N-Acylated HTHP can be obtained by treatingN,O-diacylated HTHP with ammonia. The reactions of 2,2-dialkyl(alkylene)-substituted HTHP with acid chlorides or phenyl isocyanate giveN,O-diacylated orN,O-diphenyl-carbamoylated β-aminopropionohydroxamic acid, respectively. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2327–2332, December, 1999.     

S-ArylN,N-dialkylamidothiosulfates, a novel class of sulfenic acid derivatives

A method for the synthesis ofS-arylN,N-dialkylamidothiosulfates, a novel class of sulfenic acid derivatives, was proposed. The method is based on the reaction of arenesulfenyl chlorides withN,N-dialkylamidosulfinic acids or with secondary amines in liquid SO₂ in the presence of triethylamine. In the presence of halogen-containing Lewis acids,S-arylN,N-dialkyl-amidothiosulfates add to the C=C bonds to give aryl β-haloalkyl sulfides. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1484–1487, August, 2000.     

Preparation ofN-nitrohydroxylamines by the substituting nitration method

N-Nitro-N-methyl-O-substituted hydroxylamines were synthesized in high yields by nitration of appropriateN-acetylhydroxylamines with nitrogen pentoxide.Translated fromIzvestiya Akademioi Nauk. Seriya Khimicheskaya, No. 3, pp767–769, March, 1996.     

Convenient synthesis and NMR spectral studies of variously substituted <Emphasis Type="Italic">N</Emphasis>-methylpiperidin-4-one-<Emphasis Type="Italic">O</Emphasis>-benzyloximes

Abstract  A series of variously substituted N-methylpiperidin-4-one-O-benzyloximes were synthesized by three different methods. Among them, the direct conversion of 2,6-diarylpiperidin-4-ones into the corresponding oxime ethers (method A) was proved to be better than the other two methods in the sense of good yield, convenience, easy work-up and quick reaction time. All the synthesized compounds are characterized by IR, Mass and NMR (¹H NMR, ¹³C NMR, ¹H-¹H COSY, ¹H-¹³C COSY and HMBC) spectral studies. The conformational preference of the synthesized oxime ethers with/without alkyl and aryl substituents at C-3/C-5 and C-2/C-6 is discussed using the spectral data. The observed chemical shifts and coupling constants suggest that the synthesized oxime ethers adopt chair conformation with equatorial orientation of all the substituents, whereas 1-methyl-3-isopropyl-2,6-diphenylpiperidin-4-one-O-benzyloxime also exists in boat conformation. Based on the NMR data, the effects of oximination on ring carbons and their associated protons and alkyl substituents are discussed. In addition, the effect of NMe group on the 2,6-diarylpiperidin-4-one-O-benzyloximes was also studied. Graphical abstract        

Mercaptan addition to 1-<Emphasis Type="Italic">O</Emphasis>-allyl-2,3,4,6-tetra-<Emphasis Type="Italic">O</Emphasis>-acetyl-<Emphasis Type="Italic">β</Emphasis>-D-galactopyranose

Addition of ethyl-, propyl-, and n-butylmercaptans to 1-O-allyl-2,3,4,6-tetra-O-acetyl-β-D-galactopyranose in the presence of benzoyl peroxide catalyst was studied for the first time. The products were 1-O-(3-ethylthiopropyl)-2,3,4,6-tetra-O-acetyl-β-D-galactopyranose, 1-O-(3-propylthiopropyl)-2,3,4,6-tetra-O-acetyl-β-D-galactopyranose, and 1-O-(3-butylthiopropyl)-2,3,4,6-tetra-O-acetyl-β-D-galactopyranose. Deacetylation of 1-O-(3-ethylthiopropyl)-2,3,4,6-tetra-O-acetyl-β-D-galactopyranose produced 1-O-(3-ethylthiopropyl)-β-D-galactopyranose. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 209–211, May–June, 2007.     

Syntheses based on anabasine. Preparation and transformations of N-oxides

The oxidation of N-acetyl-and N-benzoylanabasine with the tert-butyl hydroperoxide (TBHP)— MoCl₅ system or MCPBA proceeds selectively at the nitrogen atom of the pyridine ring. The oxidation of N-methylanabasine under similar conditions gives a mixture of stereo-isomeric N-oxides at the piperidine nitrogen atom, their ratio depending on the reagent used. The oxidation of anabasine by TBHP— MoCl₅ or MCPBA is accompanied by dehydrogenation and results in anabaseine N-oxide. The reactions of anabasine and anabaseine pyridine N-oxides with acetic anhydride were investigated. The substituted 1H-3-pyridin-2-ones were prepared. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 322—328, February, 2006.     

Si-Containing Amides of Phosphoric Acid

Summary. The first representative of the N-silylmethylamides of phosphoric acid O=P[NMe(CH₂SiMe _n (OEt)_3-n ]₃ have been synthesized by interaction of MeNHCH₂SiMe _n (OEt)_3-n (n = 2, 3) with POCl₃. The interaction of the N,N′,N″-trimethyl-N,N′,N″-tris[(ethoxydimethyl- silyl)methyl]triamide phosphoric acid with BF₃·Et₂O or BCl₃ results in the formation of the N,N′,N″-trimethyl-N,N′,N″-tris[(fluorodimethyl-silyl)methyl]triamide phosphoric acid or N,N′,N″-trimethyl-N,N′,N″-tris[(chlorodimethylsilyl)methyl]triamide phosphoric acid. NMR data show on the tetracoordinate state of silicon in these products. Professor Vadim Aleksandrovich Pestunovich, our chief, teacher and friend died on July 4^th, 2004     

New method for the synthesis of 2-substitutedN, N′-diacylimidazolidines

A method for the synthesis of 2-substitutedN, N′-diacylimidazolidines was developed. The method is based on the reactions of acylating reagents (carboxylic acid chlorides and anhydrides, sulfonic acid chlorides, a carbamic acid chloride, and ethyl chlorocarbonate) with Schiff's bases prepared by the reaction ofN-acylethylenediamines with aldehydes. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya. No. 5, pp. 896–900, May, 2000.