Synthesis of 1-aryl-2-propanones

A new convenient synthesis of a series of 1-aryl-2-propanones using aromatic amines as precursors, via diazo-reaction and improved Meerwein arylation reaction under mild conditions, was achieved. In addition, 1-[3,5-bis(trifluoromethyl)phenyl]-2-propanone is a new compound among the synthesized compounds. This approach is an efficient synthetic method for the aryl-propanones with different substituting groups. __________ Translated from Chinese Journal of Organic Chemistry, 2007, 27(10): 1244–1249 [译自: 有机化学]     

Synthesis of 2-aryl-6-(4-bromophenyl)-4-(2,2-dichlorovinyl)pyridines with the use of 1-aryl-5,5-dichloropenta-2,4-dien-1-ones

Heating 1-aryl-5,5-dichloropenta-2,4-dien-1-ones with 4-bromophenacylpyridinium bromide in AcOH in the presence of AcONH₄ gave 2-aryl-6-(4-bromophenyl)-4-(2,2-dichlorovinyl)pyridines. The reaction products were structurally characterized by¹H and¹³C NMR spectroscopy. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 955–957, May, 2000.     

Synthesis of carbonyl compounds based on the products of addition of polyhaloalkanes to unsaturated systems. Reactions of 1-aryl-5,5-dichloropenta-2,4-dien-1-ones with ethyl acetoacetate

The reactions of 1-aryl-5,5-dichloropenta-2,4-dien-1-ones with ethyl acetoacetate in the presence of EtONa give ethyl 4-aryl-6-(2,2-dichlorovinyl)-4-hydroxy-2-oxocyclohexane-carboxylates. The structures of the reaction products were confirmed by¹H and¹³C NMR spectroscopy and by X-ray diffraction analysis. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp.     

Novel reaction of 1-aryl-2-bromodiazene 1-oxides with olefins. Synthesis of 1-aryl-2-(2-bromoalkyl)diazene 1-oxides

The addition of 1-aryl-2-bromodiazene 1-oxides to olefins yields 1-aryl-2-(2-bromoalkyl)diazene 1-oxides (4). A radical mechanism of the reaction has been suggested. Compounds4 decompose to give bromohydrazones of formaldehyde and aldehydes. The structural factors that affect the rate of this process are discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 917–923, May, 1995.The work was carried out in the Scientific Educational Center of the Institute of Organic Chemistry of the RAS with financial support of the Russian Foundation for Basic Research (Project No. 93-03-18461).     

14N and 15N NMR Spectroscopy of 2-Methyl-4,5-dinitro-1,2,3-triazole and of Substituted 2-Methyl-4(5)-nitro-1,2,3-triazole 1-Oxides

Analysis of the ¹⁴N and ¹⁵N NMR spectroscopic data of 2-methyl-4,5-dinitro-1,2,3-triazole and of substituted 2-methyl-4(5)-nitro-1,2,3-triazole 1-oxides has shown the possibility of applying them for confirmation of the structures of the studied compounds.     

Intramolecular interaction between ortho-azido and azoxy groups as a new way of forming a N—N bond. Synthesis of 2-alkylbenzotriazole 1-oxides

Heating of 2-(alkyl-NNO-azoxy)-1-azidobenzenes in boiling benzene gave 2-alkyl-benzotriazole 1-oxides (Alk = Me, Et, Prⁱ, and Bu^t). This first-order reaction involves an earlier unknown intramolecular interaction between the azido and azoxy groups with simultaneous release of molecular nitrogen. The cyclization rate increases in the following sequence of the alkyl groups: Me < Et < Prⁱ < Bu^t. Complete assignment of the signals in the ¹H, ¹³C, and ¹⁴N NMR spectra of 2-alkylbenzotriazole 1-oxides was performed. Dedicated to Corresponding Member of the Russian Academy of Sciences E. P. Serebryakov on the occasion of his 70th birthday. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 989–996, April, 2005.     

Nucleophilic substitution of hydrogen in the reaction of 1,2,4-triazin-4-oxides with cyanamide

It was shown that cyanamide can successfully be used in reactions of nucleophilic substitution of hydrogen with 1,2,4-triazin-4-oxides in the presence of a base to give 5-cyanoimino-1,2,4-triazines. It was found by¹³C NMR spectroscopy that these compounds and their alkylation products at the cyclic nitrogen atom exist in the form of 5-cyanoimino-2,5-dihydro-1,2,4-triazines. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1128–1130, June, 2000.     

Stereochemicai study of 7-aryl-1,7,8,8a-tetrahydro-3(2H)indolizinones by1H and13C NMR

Stereochemistry of 7-aryl-1,7,8,8a-tetrahydro-3(2H)-indolizinones was studied by¹H and¹³C NMR. Complete assignment of¹H NMR signals and analysis of¹H-¹H coupling constants were performed using the iterative PANIC program. Values of³ J _6,7,³ J _7,8endo, and⁴ J _5,7 allow one to unambiguously identify the correspondingexo- andendo-stereoisomers. For stereoisomers with exo-orientation of H(7), complete assignment of¹³C NMR signals was performed on the basis of analysis of the¹³C-¹H coupling constants using two dimensional heteronuclear shift-correlating spectroscopy.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 591–593, March, 1996.     

Interaction of decacarbonyldimanganese and decacarbonyldirhenium with 1-aryl-3-cyanoprop-2-en-1-ones

The reactions of M₂(CO)₁₀ (M = Mn, Re) withtrans-1-aryl-3-cyanoprop-2-en-1-ones in the presence of Me₃NO proceed with replacement of the CO ligand and lead to complexeseq-(1-aryl-3-cyanoprop-2-en-1-on)nonacarbonyldimanganese andeq-(1-aryl-3-cyanoprop-2-en-1-on)nonacarbonyldirhenium complexes where the metals are bonded with the ligand through the nitrogen atom of the cyanogroup. The treatment of (1-phenyl-3-cyanoprop-2-en-1-on)nonacarbonyldirhenium with a second equivalent of the ligand resulted in the disubstituted complex,eq,eq-bis(1-phenyl-3-cyanoprop-2-en-1-on)octacarbonyldirhenium in a good yield. The structures of the obtained complexes are discussed on the basis of¹³C,¹H NMR, and IR-spectroscopy.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1485–1487, August, 1994.This work was supported in part by the Russian Foundation for Basic Research (grant No 93-03-4028).     

Effects of different GIAO and CSGT models and basis sets on 2-aryl-1,3,4-oxadiazole derivatives

The direct molecular structure implementations of the gage-including atomic orbital (GIAO), individual gages for atoms in molecules (IGAIM) and continuous set of gage transformations (CSGT) methods for calculating nuclear magnetic shielding tensors at both the Hartree-Fock (HF) and density functional (B3LYP) levels of theory with 6-31G(d), 6-311G(d), 6-31++G(d,p), 6-311++G(d,p), and 6-311++G(df,pd) basis sets are presented. Dependence on the ¹H and ¹³C NMR chemical shifts on the choice of method and basis set have been investigated. Also, these chemical shifts of 2-aryl-1,3,4-oxadiazoles 5a–g have been performed related to dihedral angles (C4–C3–C2–O) of two conformers. The optimized molecular geometries and ¹H and ¹³C chemical shift values of 2-aryl-1,3,4-oxadiazoles 5a–g in the ground state have been obtained. The linear correlation coefficients of ¹³C NMR chemical shifts for these molecules were given. The new nuclear magnetic shielding tensors of tetramethylsilane (TMS) were calculated. The data of 2-aryl-1,3,4-oxadiazole derivatives display significant molecular structure and NMR analysis. Also, these provide the basis for future design of efficient materials having the 1,3,4-oxadiazole core.     

Structures and conformations of 1-aryl-1,4-dihydro-3(2H)-isoquinolinones

The X-ray crystal structures of series of 1-aryl-1,4-dihydro-3(2H)-isoquinolinones (1-7) have been determined. Lactame heterocyclic ring possesses more or less deformed boat conformation in all examined structures. The aryl substituent adopts the equatorial position in the structures 1-3 and the axial one in 5-7. In the structure of 4, due to extremely flattened heterocyclic ring, aryl substituent location can be named as bisectional. In all solved structures the molecules are joined into the dimers via two N-H?O hydrogen bonds. At the same time, ¹H NMR studies in DMSO-d₆ solutions were accomplished and profound analysis of ²J, ³J, and ⁵J coupling constants have shown that in isoquinolinone system the heterocyclic ring adopts the boat conformation in all investigated compounds. The stereochemical orientations of the phenyl ring at C1 do not depend on the nature of the substituent but, exclusively, on the mode of substitution. However, three forms of undulated laktam heterocyclic ring conformation in respect of 1-aryl substituent positions were confirmed by calculation (conformational analysis).     

Condensation products of 1-aryl-4-hydrazinocarbonyl-2-pyrrolidinones with diketones

The reactions of 1-aryl-4-hydrazinocarbonyl-2-pyrrolidinones with 2,4-pentanedione and 2,5-hexanedione have been studied. It was found that heating the hydrazinocarbonyl compounds with 2,4-pentanedione gave 3,5-dimethylpyrazole compounds and with 2,5-hexanedione gave 1-substituted 2,5-dimethylpyrroles. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 229–232, February, 2008.     

Regioselective synthesis of 2-unsubstituted 1-aryl-4- and 1-aryl-5-acylimidazoles

An efficient and simple method for the synthesis of 2-unsubstituted 1-aryl-4- and 1-aryl-5-acylimidazoles has been developed. It consists in the condensation of α-diketone monooximes with aromatic amines and formaldehyde on the presence of boron trifluoride etherate, leading to the formation of stable boron trifluoride complexes of N-oxides. Further reduction of these complexes led to the corresponding imidazoles. This method permits broad variations of substituents in the aryl part of these compounds.     

Synthesis of 1-pyrroline 1-oxides analogous to pseudouridine

Pseudouridine (ψ-uridine, Ψ) aza′-analogues with a 5,5-bis(hydroxymethyl)-1-pyrrolin-2-yl 1-oxide as the glycone mimic were obtained by the addition of (2,4-dimethoxypyrimidin-5-yl)magnesium bromide to 1-aza-7,14-dioxadispiro[4.2.5.2]pentadec-1-ene 1-oxide (3), followed by oxidation and removal of the protecting groups. The analogous synthesis from (2,4-dimethoxypyrimidin-5-yl)lithium and 3 was less efficient; in the first step of the reaction sequence, competing dimerisation of 3 predominated over addition of the organolithium agent to 3.     

Polymerization Reactions in an Al(OBus)3-(COOH)2 System

Reactions in an Al(OBu^s)₃-(COOH)₂ (OA)-tetrahydrofuran (THF)/(CD₃)₂SO (DMSO-d₆) system (Al(OBu^s)₃: THF : DMSO-d₆: OA = 1 : 5 : 5 : x, x = 0.01 –3) were studied, without the addition of water and the process was monitored by NMR. When x 0.3, homogeneous solutions were obtained, whereas white precipitates formed with x 0.7. The formation of sec-butyl alcohol was evident with x 0.6, indicating that oxalate groups coordinate to aluminum to release sec-butyl alcohol. ¹³C NMR spectra of the solutions after 1 day suggest the presence of polymeric species if 0.03 x 0.6. The addition of a small amount of water resulted in the formation of a white precipitate (Al(OBu^s)₃: THF : DMSO-d₆ : OA : H₂O = 1 : 5 : 5 : 0.3 : y,y = 0.03–0.3), indicating that water, possibly formed by esterification in the Al(OBu^s)₃-OA-THF/DMSO-d₆ system, does not take a major role in the present system.     

Reactions of α-pentafluorophenylpyrylium salts with hydroxylamine

The reactions of α-pentafluorophenylpyrylium salts with hydroxylamine in ethanol afford isoxazoline derivatives and/or pyridine N-oxides depending on the steric characteristics of the substituent in the second α position. The structure of 2-hydroxy-2-pentafluorophenyl-4-phenyl-2,3,5,6,7,8-hexahydroquinoline 1-oxide, which was synthesized by the reaction of 2-pentafluorophenyl-4-phenyl-5,6,7,8-tetrahydrobenzopyrylium perchlorate with NH₂OH, was established by X-ray diffraction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 402–407, February, 2008.     

Reactions of 2-aryl-4-arylidene-4<Emphasis Type="Italic">H</Emphasis>-oxazol-5-ones with 3-amino-1,2,4-triazole, 5-aminotetrazole,and 2-aminobenzimidazole

The reactions of 3-amino-1,2,4-triazole, 5-aminotetrazole, and 2-aminobenzimidazole with 2-aryl-4-arylidene-4H-oxazol-5-ones (azlactones) were studied. The electron-releasing properties of the azole ring were demonstrated to influence the reaction pathway of azlactones with aminoazoles. The structures of the resulting compounds were established by ¹H and ¹³C NMR spectroscopy using spin-spin decoupling and the nuclear Overhauser effect.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2730–2733, December, 2004.     

The tert-butyl-NNO-azoxy group in the synthesis of 1,2,4-benzotriazin-3(4H)-one 1-oxides

Treatment of 2-(tert-butyl-NNO-azoxy)anilines with phosgene at 20 °C was proposed as a novel route to 1,2,4-benzotriazin-3(4H )-one 1-oxides. This method involves a new reaction, viz., an intramolecular interaction of the tert-butyl-NNO-azoxy group with a C-electrophile (leading to the formation of the N(2)—C(3) bond of the triazine ring) followed by elimination of the tert-butyl group. Complete assignment of the signals in the ¹H and ¹³C NMR spectra of the compounds obtained was performed. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1507–1509, August, 2007.     

A multinuclear NMR study in the solid state and in solution of thallium(I) tris-(pyrazol-1-yl)borates (thallium scorpionates)

The ¹H, ¹³C and ¹⁵N NMR spectroscopic properties of six thallium tris-(pyrazol-1-yl)borates, including a tetrakis derivative, were determined. The results in solution were necessary to understand those, more complicated, in the solid state. A collection of ²⁰⁵Tl-¹⁵N and ²⁰⁵Tl-¹³C couplings was measured in the latter state. Among those, a very large coupling constant (between 194 and 282 Hz) has been measured on the carbon at the position 4 of the pyrazole ring in several compounds and particularly for the cyclobutyl derivative [Tl(Tp^Cbu)]. It has been assigned to a direct interaction of the 4-C-H ? Tl type and related to the X-ray structures, when available.     

2D-NMR of natural products,part V Structure elucidation and complete1H- and13C-assignment of resin acid derivatives

Application of 2D-NMR-techniques including heteronuclear 2D-J-resolved spectroscopy and¹H-¹³C-2 D-shift correlation is used to assign the¹H- and¹³C-resonances of resin acid derivatives.

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2D-NMR von Naturprodukten, 5. Mitt.: Strukturaufklärung und komplette ^1H-und ^13C-Zuordnung von Harzsäure-Derivaten

Zusammenfassung 2D-NMR-Methoden (2D-J-resolved-Spektren,¹H-¹³C-Shiftkorrelations-spektren) erlauben die Zuordnung der¹H- und¹³C-Signale von Harzsäurederivaten.