Lithiation-methylation of thiasilinane 1-oxides

Lithiation-methylation of 3,3-dimethyl-1λ⁴,3-thiasilinane 1-oxide and 4,4-dimethyl-1λ⁴,4-thiasilinane 1-oxide under the action of butyllithium or lithium diisopropylamide and methyl iodide was studied. In both cases, monomethylation proceeds selectively α to the sulfoxide group to form 2,3,3-trimethyl-1λ⁴,3-thiasilinane 1-oxide and 2,4,4-trimethyl-1λ⁴,4-thiasilinane 1-oxide, respectively. Subsequently, 2,3,3-trimethyl-1λ⁴,3-thiasilinane 1-oxide undergoes monomethylation into the same α position to give 2,2,3,3-tetramethyl-1λ⁴,3-thiasilinane 1-oxide, while 4,4-dimethyl-1λ⁴,4-thiasilinane 1-oxide is dimethylated into the neighboring α’ position to form two stereoisomers of 2,4,4,6-tetramethyl-1λ⁴,4-thiasilinane 1-oxide with axial-equatorial or equatorial-equatorial methyl groups in the 2 and 6 positions.     

Expression of 4-1BB and 4-1BBL in thymocytes during thymus regeneration

4-1BB, a member of the tumor necrosis factor receptor (TNFR) superfamily, is a major costimulatory receptor that is rapidly expressed on the surface of CD4⁺ and CD8⁺ T cells after antigen- or mitogen-induced activation. The interaction of 4-1BB with 4-1BBL regulates immunity and promotes the survival and expansion of activated T cells. In this study, the expression of 4-1BB and 4-1BBL was examined during regeneration of the murine thymus following acute cyclophosphamide-induced involution. Four-color flow cytometry showed that 4-1BB and 4-1BBL were present in the normal thymus and were preferentially expressed in the regenerating thymus, mainly in CD4⁺CD8⁺ double-positive (DP) thymocytes. Furthermore, the CD4^loCD8^lo, CD4⁺CD8^lo and CD4^loCD8⁺ thymocyte subsets, representing stages of thymocyte differentiation intermediate between DP and single-positive (SP) thymocytes, also expressed 4-1BB and 4-1BBL during thymus regeneration but to a lesser degree. Interestingly, the 4-1BB and 4-1BBL positive cells among the CD4⁺CD8⁺ DP thymocytes present during thymus regeneration were TCR^hi and CD69⁺ unlike the corresponding controls. Moreover, the 4-1BB and 4-1BBL positive cells among the intermediate subsets present during thymus regeneration also exhibited TCR^hi/int and CD69^+/int phenotypes, indicating that 4-1BB and 4-1BBL are predominantly expressed by the positively selected population of the CD4⁺CD8⁺ DP and the intermediate thymocytes during thymus regeneration. RT-PCR and Western blot analyses confirmed the presence and elevated levels of 4-1BB and 4-1BBL mRNA and protein in thymocytes during thymus regeneration. We also found that the interaction of 4-1BB with 4-1BBL promoted thymocyte adhesion to thymic epithelial cells. Our results suggest that 4-1BB and 4-1BBL participate in T lymphopoiesis associated with positive selection during recovery from acute thymic involution.     

In situ X-ray absorption and diffraction studies of carbon coated LiFe1/4Mn1/4Co1/4Ni1/4PO4 cathode during first charge

Synchrotron based in situ X-ray absorption spectroscopy (XAS) and X-ray diffraction (XRD) techniques are used to study electronic and crystal structure changes of the carbon coated LiFe_1/4Mn_1/4Co_1/4Ni_1/4PO₄ (LiFe_1/4Mn_1/4Co_1/4Ni_1/4PO₄/C) cathode material for Li-ion batteries during the first charge. In situ Fe, Mn, Co and Ni K-edge XAS results revealed that the three voltage plateaus at ～3.6, 4.2 and 4.7 V vs. Li/Li⁺ are attributed to the redox reactions of Fe²⁺/Fe³⁺, Mn²⁺/Mn³⁺ and Co²⁺/Co³⁺, respectively, while the apparent capacities above 4.9 V is not originated from the Ni²⁺/Ni³⁺ redox, but very likely from the electrolyte decomposition. Interesting phase transition behaviors of LiFe_1/4Mn_1/4Co_1/4Ni_1/4PO₄/C were observed with the formation of an intermediate phase and the solid solution regions. Combined in situ XAS and XRD techniques indicate fast electronic structural changes and slow bulk crystal structural changes.     

Spin-spin coupling constants of 13C-1H and 1H- 1H in 4-substituted pyridines

The spin-spin coupling constants (SSCC) of ¹³C-¹H and ¹H-¹H in 4-substituted pyridines, C₅H₄NX [X=,CN, COCH₃, COOCH₃, N(CH₃)₂, NO₂, OCH₃, Cl, Br], were investigated. To determine the constants, the proton-coupled NMR spectra of ¹³C and ¹³C-satellites in the PMR spectra of the compounds, recorded for monomolecular solutions of 4-substituted pyridines in DMSO-D₆, were analyzed. The interrelationship of the SSCC of ¹³C-¹H and ¹H-¹H in 4-substituted pyridines with the analogous constants in monosubstittued benzenes were obtained. The correlations of the constants with the F- and R-parameters of the substituents are discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 948–952, July, 1984.     

Heats of solution of 1∶1 electrolytes in 1-propanol,and derived enthalpies of transfer from water

Heats of solution of 13 11 electrolytes in 1-propanol have been determined calorimetrically at various electrolyte concentrations, and extrapolated to zero concentration to give H _s ^o values for these electrolytes. Together with literature data on three additional 11 electrolytes, these measurements yield a self-consistent set of single-ion enthalpies of transfer from water to 1-propanol. Values are tabulated for 10 univalent cations and five univalent anions. It is shown that the H _t ^o (Ph ₄ As⁺)=H _t ^o (Ph ₄ B^–) assumption yields chemically reasonable single-ion values. Using this assumption, it may be deduced that all the univalent ions studied have about the same enthalpy in 1-propanol as in methanol.     

Metal Complexes of 1-Allenylimidazoles

Monomeric complexes ML _n X _m , where M = Co^{2 +}, Ni^{2 +}, Zn^{2 +}, Cd^{2 +}, Cu^{2 +}, Pd^{2 +}, Sn^{4 +}; L = 1-allenylimidazole, 1-allenyl-2-methylimidazole, 1-allenylbenzimidazole; n = 2, 4; m = 1, 2, 4; X = Cl, OCOCH3, was prepared for the first time, and their structure was studied by NMR and IR spectroscopy. In the complexes, 1-allenylimidazoles act as monodentate ligands coordinating via the heteroring ^N3atom, and the CH2 = C = CH group is stabilized by coordination of the azolyl ring with the metal, which hinders elec- tron transfer from the heteroring to the allenyl fragment. The prospective use of the complexes of Zn(OCOCH3)2 with 1-allenyl imidazole derivatives as antidotes and antihypoxants was demonstrated.     

Chemistry of Benzocyclopropenes. 1H-and 13C-NMR. Spectra of 2, 5-dideuterio-1-fluorobenzocyclopropenium ion

Preparation of 1, 1-difluorobenzocyclopropene (4) and of its 2, 5- and 3, 4-dideuterio derivatives 4a and 4b is reported. Upon ionization in cold fluorosulfonic acid, 4 affords 1-fluorobenzocyclopropenium ion (6) . ¹H- and ¹³C-NMR. spectra of 4 and 6 are assigned on the basis of the data for the specifically deuteriumlabelled compounds 4a and 6a . Hydrolysis of 6a leads to 2, 5-dideuteriobenzoic acid (7a) .     

Conformational and solid-state studies of diphenyl 1-hydroxy-1-phenylethylphosphonate

The crystal structure of the title compound, diphenyl 1-hydroxy-1-phenylethylphosphonate ( 1 ), was determined by the single-crystal X-ray diffraction method. The crystallographic data for 1 are as follow: C₂₀H₁₉O₄P, M_r = 354.34, monoclinic, P2₁/n, a = 9.787(1) Å, b = 20.235(1) Å, c = 9.797(1) Å, β = 106.18(3)°, V = 1863.3(4) ų, Z = 4, D_calc = 1.26 g/cm³, λ(Mo-Ka) = 0.71073 Å, μ = 1.6 cm⁻¹, F(000) = 744, R = 0.018, and R_w = 0.032 for 2258 observed reflections. The solid-state structure in a dimeric packing mode exhibits intermolecular hydrogen bonding of the type P = O···H–O. Infrared solution studies (CCl₄) indicate that upon high dilution (10⁻⁴ M) the dimers completely dissociate to give conformers with and without intramolecular hydrogen bonds. Theoretical studies (PM3) were undertaken to determine the energy profile about the P–C torsional angle, which exhibited low energy barriers to rotation with no clear minimum energy conformation. © 1996 John Wiley & Sons, Inc.     

Crystallographic characterization of three cathinone hydrochlorides new on the NPS market: 1-(4-methylphenyl)-2-(pyrrolidin-1-yl)hexan-1-one (4-MPHP), 4-methyl-1-phenyl-2-(pyrrolidin-1-yl)pentan-1-one (α-PiHP) and 2-(methylamino)-1-(4-methylphenyl)pentan-1-one (4-MPD)

Cathinones belong to a group of compounds of great interest in the new psychoactive substances (NPS) market. Constant changes to the chemical structure made by the producers of these compounds require a quick reaction from analytical laboratories in ascertaining their characteristics. In this article, three cathinone derivatives were characterized by X-ray crystallography. The investigated compounds were confirmed as: 1-[1-(4-methylphenyl)-1-oxohexan-2-yl]pyrrolidin-1-ium chloride ( 1 , C₁₇H₂₆NO⁺·Cl^?, the hydrochloride of 4-MPHP), 1-(4-methyl-1-oxo-1-phenylpentan-2-yl)pyrrolidin-1-ium chloride ( 2 ; C₁₆H₂₄NO⁺·Cl^?, the hydrochloride of α-PiHP) and methyl[1-(4-methylphenyl)-1-oxopentan-2-yl]azanium chloride ( 3 ; C₁₃H₂₀NO⁺·Cl^?, the hydrochloride of 4-MPD). All the salts crystallize in a monoclinic space group: 1 and 2 in P2₁/c, and 3 in P2₁/n. To the best of our knowledge, this study provides the first detailed and comprehensive crystallographic data on salts 1 – 3 .     

Reactions of 1-Allenylpyrazole and 1-Allenyl-1,2,4-triazole with Hydrogen Chloride and Metal Chlorides

1-Allenylpyrazole and 1-allenyl-1,2,4-triazole react with hydrogen chloride via proton addition at the pyridine-like nitrogen atom (N² and N⁴, respectively). In the reaction with 1-allenylpyrazole, 1-[(E)-3-chloro-1-propenyl]pyrazole is also formed via regio- and stereoselective addition of hydrogen chloride to the propadienyl group. 1-Allenylpyrazole and 1-allenyl-1,2,4-triazole act as unidentate ligands with respect to Co, Ni, Cu, Zn, Cd, Pd, and Sn, the donor centers being N² and N⁴, respectively. Apart from mononuclear coordination compounds, 1-allenylpyrazole gives rise to polymeric complexes which contain units and blocks formed by the free ligand.     

Researches on 1, 2, 4-triazoles

Determination of the acidity constants of 1-aryltetrazolinethiones-5, 4-aryl-1, 2, 4-triazolinethiones-3, 1-aryltetrazolinones-5, 4-aryl-1, 2, 4-triazolinones-3 shows that carbonyl compounds are 10^–1–10^–2 times less acid than compounds with a thione group. Acidities are found to increase considerably, 10³–10⁴ times, on passing from triazole compounds to tetrazole ones. 4-Aryl-1, 2, 4-triazolinones-3 and 1-aryl-tetrazolinones-5 are aminomethylated and cyanoethylated and the reactions found to take place at the amide nitrogen atom.For Part VI see [1].     

1, 1-Difluoro-1H-cyclopropa[a]naphthalene

1, 1-Difluorocyclopropa[a]naphthalene ( 1b ) is prepared in three steps from 4-bromo-1,2-dihydronaphthalene ( 7 ) via carbene addition, benzylic bromination and bidehydrohalogenation. Structural evidence for formation of 1b is based on ¹H- and ¹⁹F-NMR spectroscopy. Compound 1b is stable in solution at ?30°. Upon reaction with MeOH/H⁺ it is converted to a 1:2 mixture of 1- and 2-methylnaphthoate ( 10 and 11 , respectively).     

Cyclization of nitriles 41. Reaction of arylmethylenemalononitriles with malononitrile; crystal structure of 1-amino-3.5-diphenyl-2,4,4,6,6-pentacyano-1-Cyclohexene

1-Amino-3,5-diaryl-2,4,4,6,6-pentacyano-1-cyclohexenes are prepared by reaction of arylmethylenemalononitriles with malononitrile. The cyclohexene ring of (IVa) has a distorted N₂-C¹=C²-C⁷=N¹ fragment. Steric effects in (IVa) cause a substantial increase in C⁶-C¹ and C³-C⁴ bond length to 1.546(4) and 1.570(4) Å, respectively.For previous communication, see [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2771–2775, December, 1989.     

An Efficient Method for the Selective Reduction of 2-Aryl-1-Nitroalkenes to 2-Aryl-1-Nitroalkanes by 2-Phenylbenzimidazoline

Nitroalkanes have recently been demonstrated to be useful synthetic intermediates for a variety of trans- formations. They have, for example, been converted to carbonyl, la) nitrile oxide,^lb) and amino compounds.^1c) Especially, 2-aryl-1-nitroalkanes are important in connection with the synthesis of biochemically and pharmacologically interesting compounds. ²⁾ They have also been used as synthetically equivalent to enamines and enolates.³⁾ A widely employed method⁴⁾ for the synthesis of nitroalkanes involves NaBH₄ reduction of conjugated nitroalkenes. The NaBH₄ reduction of nitro- alkenes derived from aliphatic aldehydes^4b) or ketones⁵⁾ usually proceeds smoothly in good yields. However, the reduction of 2-aryl-1-nitroalkenes with NaBH₄ produces low yields of products due to undesired side reactions such as dimerization.⁴⁾     

Massenspektroskopische Untersuchungen an 2,5-Diaryl-1-(arylimino)-1λ4,2,5-thiadia-zolidin-3,4-dionen

The mass spectra of 2,5-diaryl-1-(arylimino)-1λ⁴,2,5-thiadiazolidin-3,4-diones have been examined. Some fragmentations are explained by rearrangement of the title compounds to 1,3-(diarylimino)-5-aryl-1λ⁴,2,5-thioxazolidin-4-ones and 1-oxo-2,5-diaryl-3-(arylimino)-1λ⁴,2,5-thiadiazolidin-4-ones.     

Synthesis of hexylthiols C6H13SH−1/1, 2, 3, 4−14C1/4/' /1-thiol[35S]/ and C6H13SH−2/1, 2, 3, 4−14C1/4/, /2-thiol[35S]/

A synthesis of¹⁴C and³⁵S double labelled hexylthiols: C₆H₁₃SH–1/1, 2, 3, 4–¹⁴C_1/4/, /1-thiol[³⁵S]/ and C₆H₁₃SSH–2/1, 2, 3, 4–¹⁴C_1/4/, /2-thiol[³⁵S]/ based on H₂ ³⁵S and C₆H₁₂–/1, 2, 3, 4–¹⁴C_1/4/ has been developed and described.     

Synthesis of 1-Methyl- and 1-Phenyl-closo-B12H121- by Cross Coupling of 1-Iodo-closo-B12H121- with Methyl- and Phenylzinc Chlorides,Catalyzed by Palladium Complexes

Reactions of [N⁺(n-C₄H₉)₄]₂[1-I-closo-B_{1 2}H₁ ² ₁ ^-] with MeZnCl and PhZnCl, catalyzed by (Ph₃P)₄Pd, in THF solution gave, respectively, [N⁺(n-C₄H₉)₄]₂[1-CH₃-closo-B_{1 2}H₁ ² ₁ ^-] and [N⁺(n-C₄H₉)₄]₂ [1-Ph-closo-B_{1 2}H₁ ² ₁ ^-] in good yields.     

Mass spectra of esters of α-hydroxy and α-methoxy acids

The most abundant fragment produced by electron bombardment of esters of the type R¹R²C(OR³)CO₂R⁴ is the R¹R²C = \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm O}\limits^{{\rm + } \cdot } $\end{document}R³ ion. Methyl glycollate (R¹ = R² = R³ = H, R⁴ = Me) eliminates the HCO˙ radical by a complex rearrangement involving the methylenic hydrogen atoms. The methyl and ethyl esters of methoxyacetic acid (R¹ = R² = H, R³ = Me, R⁴ = Me or Et) eliminate formaldehyde by the McLafferty rearrangement.     

Regiospecificity of nucleophilic substitution in 4,6-dinitro-1-phenyl-1H-indazole

The reactions of 4,6-dinitro-1-phenyl-1H-indazole with anionic nucleophiles RS^– and N₃ ^– lead to the regiospecific replacement of the nitro group at position 4. The reaction with N₂H₄·H₂O + FeCl₃ also results in reduction of only the 4-NO₂ group. Based on this fact, a procedure was developed for the preparation of previously unknown 3-unsubstituted 4-X-6-nitro-1-phenyl-1H-indazoles (X is a residue of a nucleophile or NH₂). Comparison of the data on the selective nucleophilic substitution (4-NO₂ group) in 3-Z-1-aryl-4,6-dinitro-1H-indazoles shows that in the case of Z = H, the regiospecificity of substitution is determined by the electronic effect of the annelated pyrazole ring.     

Structural Study of Alkaline 1-Phenyl-1H-1, 2, 3, 4-tetrazole-5-thiolate Salts: An Example of Periodicity in Alkaline Cations

The alkaline 1-phenyl-1H-1, 2, 3, 4-tetrazole-5-thiolate salts, M[C₆H₅N₄CS] (M = Li ( 1 ), Na ( 2 ), K ( 3 ), Rb ( 4 ) and Cs ( 5 )) were obtained and characterized by means of mass spectrometry (FAB⁺) and NMR (¹H; ¹³C) spectroscopy. The structures of Na ( 2 ), K ( 3 ), Rb ( 4 ) and Cs ( 5 ) compounds were determined by X-ray diffraction methods. The ligand shows a rich variety of coordination patterns with the alkaline cations. The formation of a four-membered ring MSCN in the compounds with heavier alkali cations (K, Rb and Cs) is shown. In all the cations the coordination number around it increases with the ionic radius. Compounds with Cs⁺ and Rb⁺ exhibited the formation of Cs-C and Rb-C interactions with the phenyl group.