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        

Unexpected transformations ofO-vinylacetophenone oxime in the system ButOK-THF

Transformation ofO-vinylacetophenone oxime in the system Bu^tOK-THF was studied. The reaction at 60–65 °C was shown to afford not the anticipated 2-phenylpyrrole, but, instead, 2,4-diphenylpyrrole (21% yield) and oligomer products (40% yield). The latter have the same elemental composition as the startingO-vinyl oxime but do not contain vinyloxy groups or pyrrole fragments. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 3, pp. 615–617, March, 1997.     

Hexafluoroacetone as Protecting and Activating Reagent. A New Approach to <Emphasis Type="Italic">N</Emphasis>-Glycosides

Summary. N-Glycosides of Asn and homologues have been synthesized starting from hexafluoroacetone-protected -activated Asp, Glu, and Aad derivatives and glycosylamines. The synthetic value of the new building blocks was demonstrated by the concise incorporation of N-glycosylated Asn, Gln, and Aad -amides into glycopeptides.     

Dinitramide and its salts

N,N-Dinitro derivatives of alkylurethanes, benzamide, andp-toluenesulfamide were synthesized for the first time. Their reactions with ammonia afforded the ammonium salt of dinitramide in 44–85% yields.For part 9, seeIzv. Akad. Nauk. Ser. Khim., 1996, 451 [Russ-Chem. Bull., 199645, 433 (Engl. Transl.)].Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 908–912, April, 1996.     

Nitropyrazoles

A number of substitutedN-nitropyrazoles were prepared by direct nitration of substituted pyrazoles. The dependence of the direction of nitration on the reaction conditions was studied. For Part 9, see Ref. 1. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1198–1201, June, 1997.     

Synthesis ofN-(3-azido-2-nitroxypropyl)-,N-(2,3-diazidopropyl)-, andN-(2-azido-3-methoxypropyl)-N-alkylnitramines

N-(3-Azido-2-nitroxypropyl)-N-alkylnitramines andN-(2,3-diazidopropyl)-N-alkylnitramines were prepared by nitration and azidation ofN-alkyl-N-(2-hydroxy-3-chloropropyl)sulfamates andN-(3-azido-2-hydroxypropyl)-N-alkylsulfamates. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 206–208, January, 1999.     

Alkoxylation ofC-chlorovinylsilanes

The alkoxylation and isopropylideneiminoxylation ofC-chlorovinylmethylchlorosilanes with various alcohols and acetone oxime were investigated. A series of newC-chlorovinylmethylalkoxy- and -isopropylideneiminoxysilanes was characterized by IR and¹H NMR spectra. The effect of the number of chlorine atoms inC-chlorovinylmethylchlorosilanes on their reactivity in these reactions was determined.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 737–742, April, 1995.     

The thermal decomposition of N , N -dimethyl-3-oxaglutaramic acid and the kinetics of its second-stage thermal decomposition reaction

N,N-dimethyl-3-oxa-glutaramic acid was purified and characterized by ¹H-NMR, Fourier transform infrared spectroscopy (FT-IR) and elemental analysis. The thermal decomposition of the title compound was studied by means of thermogravimetry differential thermogravimetry (TG-DTG) and FT-IR. The kinetic parameters of its second-stage decomposition reaction were calculated and the decomposition mechanism was discussed. The kinetic model function in a differential form, apparent activation energy and pre-exponential constant of the reaction are 3/2 [(1−α)^1/3−1]⁻¹, 203.75 kJ·mol⁻¹ and 10^17.95s⁻¹, respectively. The values of ΔS ^≠, ΔH ^≠ and ΔG ^≠ of the reaction are 94.28 J·mol⁻¹·K⁻¹, 203.75 kJ·mol⁻¹ and 155.75 kJ·mol⁻¹, respectively. Supported by the National Natural Science Foundation of China (Grant No. 20106009)     

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.     

Solvation Structure and Complexation of the Manganese(II) Ion in N,N-Dimethylpropionamide and N,N,N′,N′-Tetramethylurea Studied by Means of Titration Calorimetry and Raman Spectroscopy

Aprotic N,N-dimethylpropionamide (DMPA) and N,N,N′,N′-tetramethylurea (TMU) are both strong donor solvents and coordinate to metal ions through the carbonyl oxygen atom. These solvents show a different conformational aspect in the bulk phase, i.e., DMPA exists as either a planar cis or a nonplanar staggered conformer, while TMU exists in a single planar cis conformer. It has been established that the manganese(II) ion is solvated by five molecules in both solvents. Interestingly, although the planar cis conformer of DMPA is more favorable than the nonplanar staggered one in the bulk phase, the reverse is the case in the coordination sphere of the metal ion, i.e., a conformational change occurs upon solvation. To reveal the thermodynamic aspect of this conformational change, the complexation of Mn(II) with bromide ions in DMPA and TMU has been studied by titration calorimetry at 298 K. It was found that the Mn(II) ion forms mono-, di- and tri-bromo complexes in both solvents, and their formation constants, enthalpies and entropies were obtained. The Δ H∘₁ value for MnBr⁺ strongly depends on the solvent, i.e., it is positive (19.4 kJ-mol⁻¹) in DMPA and negative (−8.7 kJ-mol⁻¹) in TMU, whereas the Δ H^∘₂ and Δ H∘₃ values for the stepwise formation of MnBr₂ and MnBr₃⁻ are both small and negative. The enthalpy of transfer Δ_tH^∘ from DMPA to TMU, which is evaluated on the basis of the extrathermodynamic TATB assumption, is 25.5 kJ-mol⁻¹ for Mn²⁺ and −3.6 kJ-mol⁻¹ for MnBr⁺. These values indicate that the difference between the formation enthalpy of MnBr⁺ in the two solvents, Δ H^∘₁ (DMPA) – Δ H∘₁ (TMU), is mainly ascribed to the value of Δ_tH^∘(Mn²⁺). It is found that the metal ion is also five-coordinated in the monobromo complex, MnBr(DMPA)₄⁺ . The enthalpy for the conformational change of DMPA from its planar cis to the nonplanar staggered form is evaluated to be −11 and −5.5 kJ-mol⁻¹ for Mn(DMPA)₅^{2 +} and MnBr(DMPA)₄⁺, respectively. Note that these values are significantly smaller than the corresponding value (5.0 kJ-mol⁻¹) in the bulk phase. We thus conclude that, although steric hindrance among solvent molecules is reduced by replacing one DMPA of Mn(DMPA)₅^{2 +} with the relatively small bromide ion, DMPA molecules are still sterically hindered in the MnBr(DMPA)₄⁺ complex.     

Synthesis and some transformation ofN-allyl-N′-methoxy-andN-allyl-N′-tosyloxydiazeneN-oxides

The first representatives ofN-2-alkenyl-N′-alkoxydiazeneN-oxides andN-2-alkenyl-N′-sulphonyloxydiazeneN-oxides have been synthesized. Some reactions of the double bond in these compounds have been studied. The possibility of isomerization ofN-2-alkenyl-N′-alkoxydiazeneN-oxides toN-alk-1-enyl derivatives has been discovered. See Ref. 1 and the references therein. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp. 2262–2265, November, 1998.     

Structure of the syn-oxime of 2-N,N′-dimethylamino-5-methylbenzophenone C16H18N2O

The structure of the syn-isomer of 2-N,N′-dimethylamino-5-methylbenzophenone oxime is studied by X-ray diffraction and mass-spectrometry. This molecular compound crystallizes in the triclinic system. Unit cell parameters are: a = 19.5318(10) Å, c = 19.5439(17) Å, V = 6456.9(7) ų, Z = 18, space group R $ \bar 3 The structure of the syn-isomer of 2-N,N′-dimethylamino-5-methylbenzophenone oxime is studied by X-ray diffraction and mass-spectrometry. This molecular compound crystallizes in the triclinic system. Unit cell parameters are: a = 19.5318(10) ?, c = 19.5439(17) ?, V = 6456.9(7) ?³, Z = 18, space group R . The molecules are linked into centrosymmetric pseudo dimers by hydrogen bonds O-H…N formed by the oxime groups. The pathway of the electron-impact induced decomposition of the compound is discussed. Original Russian Text Copyright ? 2008 by O. V. Kulikov, L. Kh. Minacheva, and A. V. Mazepa __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 49, No. 4, pp. 791–794, May–June, 2008.     

Conformational Analysis,Infrared, and Fluorescence Spectra of 1-Phenyl-1,2-propandione 1-oxime and Related Tautomers: Experimental and Theoretical Study

Summary. Conformational analysis and frequency calculation were achieved for 1-phenyl-1,2-propandione 1-oxime and its four tautomers: 1-nitroso-1-phenyl-1-propen-2-ol, 1-nitroso-1-phenyl-2-propanone, 2-hydroxy-1-phenyl-propenone oxime, and 3-nitroso-3-phenyl-propen-2-ol. Calculations were carried out at the Hartree–Fock (HF), Density Functional Theory (B3LYP), and the second-order M?ller–Plesset perturbation (MP2) levels of theory using 6-31G^* and 6-311G^** basis sets. Five conformers with no imaginary vibrational frequency were obtained by free rotations around three single bonds of 1-phenyl-1,2-propandione-1-oxime: Ph–C(NOH)C(O)CH₃, PhC(NOH)–C(O)CH₃, and PhC(N–OH)C(O)CH₃. Similarly, eight structures with no imaginary vibrational frequency were encountered upon rotations around three single bonds of 1-nitroso-1-phenyl-1-propen-2-ol: Ph–C(NO)C(OH)CH₃, PhC(N–O)C(OH)CH₃, and PhC(NO)C(–OH)CH₃. In the same manner, six minima were found through rotations around three single bonds of 1-nitroso-1-phenyl-2-propanone: Ph–CH(NO)C(O)CH₃, PhCH(–NO)C(O)CH₃, and PhCH(NO)–C(O)CH₃. Also, two minima were found through rotations around four single bonds of 2-hydroxy-1-phenyl-propenone oxime: Ph–C(NOH)C(OH)CH₂, PhC(N–OH)C(OH)CH₂, PhC(NOH)–C(OH)CH₂, and Ph-C(NOH)C(–OH)CH₂. Finally, two minima were found through rotations around four single bonds of 3-nitroso-3-phenyl-propen-2-ol: Ph–CH(NO)C(OH)CH₂, PhCH(–NO)C(OH)CH₂, PhCH(NO)–C(OH)CH₂, and PhCH(NO)C(–OH)CH₂. Interconversions within the above sets of conformers were probed through scanning (one and/or two dimensional), and/or QST3 techniques. The order of the stability of global minima encountered was: 1,2-propandione-1-oxime > 1-nitroso-1-phenyl-2-propanone > 1-nitroso-1-phenyl-1-propen-2-ol > 2-hydroxy-1-phenyl-propenone oxime > 3-nitroso-3-phenyl-propen-2-ol. Hydrogen bonding appears significant in tautomers of 1-nitroso-1-phenyl-1-propen-2-ol and 2-hydroxy-1-phenyl-propenone oxime. The CIS simulated λ_max for the first excited singlet state (S₁) of 1-phenyl-1,2-propandione 1-oxime is 300.4 nm, which was comparable to its experimental λ_max of 312.0 nm. The calculated IR spectra of 1-phenyl-1,2-propandione 1-oxime and its tautomers were compared to the experimental spectra.     

Crystal and molecular structure ofN-phenyl-4-nitrobenzamidoxime

N-Phenyl-4-nitrobenzamidoxime has been studied by X-ray structural analysis. In two crystallographically independent molecules1A and1B, amidoxime groups adopt a planarZ configuration, and these fragments are in ans-trans conformation with respect to the =N-O and C-N(H) bonds; an intramolecular NH...O bond occurs. The nitrophenyl and phenyl groups are rotated with respect to the amidoxime plane [ONCN] by –57 and –32° in1A and –38 and –22° in1B, respectively. The rotation of the fragments about the C(1)-N(2) bond is –28 (1A) and –35° (1B). In crystals, molecules1A and1B are linked in oxime dimers through two intermolecular =N...(HO) hydrogen bonds; dimers form double chains through two NH...(O₂N) hydrogen bonds.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1516–1519, August, 1995.The work was supported by the Russian Foundation for Basic Research (Project No. 93-03-05069).     

(N-methyl-N-alkoxymethylaminomethyl)dialkoxysilanes and bis[N-methyl-N-(dialkoxysilylmethyl)amino]methanes

(N-methyl-N-alkoxymethylaminomethyl)-dialkoxysilanes and bis[N-methyl-N-(dialkoxymethyl)amino]methanes were first obtained by the interaction of (N-methylaminomethyl) dialkoxy-R-silanes with chloromethyl alkyl ethers in yields of 40–67% and 10–25 %, respectively.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 382–383, February, 1995.     

Synthesis of potassium salts ofO-substitutedN-nitrohydroxylamines

Potassium salts of O-substitutedN-nitrohydroxylamines were synthesized by nitration of O-substituted.N-acetylhydroxylamines followed by treatment of the reaction products with potassium methoxide.Translated fromIzyestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 178–179, January, 1994.     

Reaction of hexafluoropropylene and its oligomers with acetone oxime

Reactions of perfluoropropylene and its oligomers with acetone oxime in the presence of a base afford perfluoroalkyl and/or perfluoroalkenyl ethers of acetone oxime. When heated to 100 °C, the 3-perfluoro-2-methyl-2-pentenyl ether of acetone oxime (3) is quantitatively converted to 4-hydroxy-3-methyl-5,5-bistrifluoromethyl-4-pentafluoroethyl-1-pyrroline (4), the structure of which was established by X-ray diffraction analysis. A convenient one-stage synthesis of perfluoro-3-isopropyl-4-methyl-3-penten-2-one (7) was proposed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1068–1072, June, 1994.     

Reaction of hydroxyiminoacetophenone withp-toluenesulfonyl chloride and an X-ray diffraction study of the reaction product

2-Benzoyloxy-2-phenylmalononitrile is formed instead of the expected oxime tosylate in the reaction of hydroxyiminoacetophenone withp-toluenesulfonyl chloride. The structure of the product was confirmed unambiguously by X-ray diffraction analysis. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 872–874, April, 1997.     

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.     

Dinitramide and its salts

The dinitramide anion shows ambident properties. Its reactions with alkylating reagents give rise toN- orO-alkylated products or their mixtures. The reactions of alkylated products with bases were studied.For the previous communication, see V. A. Shlyapochnikov, G. I. Oleneva, N. O. Cherskaya, O. A. Luk'yanov, V. P. Gorelik, O. V. Anikin, and V. A. Tartakovsky,Izv. Akad. Nauk, Ser. Khim., 1994, 1610 [Russ. Chem. Bull., 1994,43, No. 11 (Engl. Transl.)].Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1775–1778, October, 1994.