Alkylation of 2-(methylsulfanyl)-6-polyfluoroalkylpyrimidin-4(3<Emphasis Type="Italic">H</Emphasis>)-ones with haloalkanes

The alkylation of ambident anions of 2-(methylsulfanyl)-6-(polyfluoroalkyl)pyrimidin-4(3H)-ones with 4-bromobutyl acetate leads to concurrent formation of O- and N-(4-acetoxybutyl) derivatives. Polar aprotic solvents favor formation of the O-isomer, and weakly polar dioxane favors N-alkylation. The reaction of 2-(methylsulfanyl)-6-(trifluoromethyl)pyrimidin-4(3H)-one with an equimolar amount of 1,2-dibromoethane in polar acetonitrile gives a mixture of N,N-, O,O-, and N,O-bridged bis-pyrimidines, as well as N- and O-[2-(methylsulfanyl)ethyl] derivatives, whereas in the presence of 10 equiv of 1,2-dibromoethane the N,O-isomer is formed as the only product. The reaction in weakly polar tetrahydrofuran yields N,N- and N,O-bispyrimidines.     

Synthesis and structure of bis(1,2-diaminoethane) copper(II) bis(<Emphasis Type="Italic">o</Emphasis>-hydroxybenzoate) monohydrate and <Emphasis Type="Italic">trans</Emphasis>-diaquabis(1,2-diaminoethane)copper(II) bis(<Emphasis Type="Italic">o</Emphasis>-aminobenzoate)

X-ray structural analysis has been performed for two complex compounds: Cu(en)₂(o-HB)₂H₂O (I) (a = 16.873(4) Å, b = 8.713(2) Å, c = 14.803(3) Å, β = 91.15(2)°, V = 2175.8(8) ų, C2/c, Z = 4, R(F) = 0.0263, 1516 reflections with I > 3σ (I)) and [Cu(en)₂(OH₂)₂]²⁺(o-AB^?)₂ (II) (a = 7.488(5) Å, b = 22.122(8) Å, c = 7.856(5) Å, β = 118.77(2)°, V = 1140.7(11) ų, P2₁/n, Z = 2, R(F) = 0.0432, 1684 reflections with I > 3σ(I)) synthesized under identical conditions (en is ethylenediamine, o-HB is o-hydroxybenzoate, and o-AB is o-aminobenzoate). Although the compounds were assumed to have similar structures and the Cu-Lig bond lengths and the cis and trans angles are acceptable for an octahedral structure, the geometric parameters of o-HB suggest that the copper atom has a plane square environment.     

Synthesis of pyranopyrazoles,benzopyrans, amino-2-chromenes and dihydropyrano[<Emphasis Type="Italic">c</Emphasis>]chromenes using ionic liquid with dual Brønsted acidic and Lewis basic sites

An efficient ionic liquid with both Brønsted acidic and Lewis basic sites, namely 1,4-dimethyl-1-(4-sulphobutyl)piperazinium hydrogen sulphate (IL1), was synthesised and characterised. IL1 is a “green”, homogeneous and reusable catalyst for: i) the synthesis of pyranopyrazoles (Va-Vj)and benzopyrans (VIa-VIj and VIIa-VIIf) at ambient temperature under solvent-free conditions and ii) the synthesis of amino-2-chromenes (VIIIa-VIIIi and IXa-IXi) and dihyropyrano[c]chromenes (Xa-Xi) at 80 °C under solvent-free conditions. The reactions were rapid with excellent product yields. In addition, the double Brønsted acid, 1,4-dimethyl-1,4-bis(4-sulphobutyl)piperazinium hydrogen sulphate (IL2), was prepared to evaluate the cooperation efficiency of their Brønsted acidic and Lewis basic sites as compared with the double Brønsted acidic sites in IL1.     

Glycosylation of panaxadiol

Glycosylation of 3β,12β-dihydroxy-20R,25-epoxydammarane (panaxadiol) (1) under Koenigs–Knorr, Helferich, and ortho-ester reaction conditions was studied. Condensation of panaxadiol and 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosylbromide (2) in the presence of silver oxide and 4-Å molecular sieves in dichloroethane gave a mixture of acetylated panaxadiol 3- and 12-O-β-D-glucopyranosides (3:1 ratio). Reaction of diol 1 and D-glucose tert-butylorthoacetate (3) in the presence of 2,4,6-collidinium perchlorate in chlorobenzene resulted in regioselective formation of panaxadiol 12-O-β-D-glucopyranoside tetraacetate. Reaction of equimolar amounts of 1 and glycosyl donor 2 in the presence of Hg(II) cyanide in nitromethane at 90°C was accompanied by opening of the tetrahydropyran ring and gave 3β,12β,25-trihydroxydammar20(22)E-ene 12-O-β-D-glucopyranoside tetraacetate. Panaxadiol 3- and 12-O-β-D-glucopyranosides and 3β,12β,25-trihydroxydammar-20(22)E-ene 12-O-β-D-glucopyranoside tetraacetate were synthesized for the first time.     

Graphene oxide promoted synthesis of <Emphasis Type="Italic">p</Emphasis>-phenylenediamine antioxidants

Three p-phenylenediamine antioxidants (p-phenylenediamine-N,N,N′,N′-tetrapropionic acid tetramethyl ester, p-phenylenediamine-N,N,N′-tripropionic acid trimethyl ester, and p-phenylenediamine-N, N′-dipropionic acid dimethyl ester) were successfully synthesized via atom-economic aza-Michael addition of pphenylenediamine to methyl acrylate p-romoted by graphene oxide in water. The synthesized compounds were characterized by NMR, ESI-MS spectra, and elemental analyses. The effects of the solvent and graphene oxide on the reaction were investigated.     

Preparation of stereochemically pure <Emphasis Type="Italic">E</Emphasis>- and <Emphasis Type="Italic">Z</Emphasis>-alkenoic acids and their methyl esters from bicyclo[<Emphasis Type="Italic">n</Emphasis>.1.0]alkan-1-ols. Application in the synthesis of insect pheromones

Oxidative cleavage of exo- and endo-alkyl- and hydroxyalkyl-substituted bicyclo[n.1.0]alkan-1-ols with (diacetoxy-λ³-iodanyl)benzene gave the corresponding methyl alkenoates exclusively with E or Z configuration of the double bond. This reaction was used as the key stage in the syntheses of stereoisomerically pure components of pest insect pheromones: (E)-dodec-9-en-1-yl acetate (European pine shoot moth Rhyacionia buoliana), (Z)-tetradec-11-en-1-yl acetate (European oak leafroller Tortrix viridana), and (3E,8Z,11Z)-tetradeca-3,8,11-trien-1-yl acetate (tomato leafminer Tuta absoluta).     

Photocrosslinkable polynorbornene-based block copolymers with enhanced dielectric and thermal properties

Block copolymers poly(endo-N-3,5-bis(trifluoromethyl)biphenyl-norbornene-pyrrolidine)-block-poly(exo-N-(cinnamoyloxyethyl)-7-oxanorborn-5-ene-2,3-dicarboximide) (endo-PTNP-b-exo-PCONBI) and poly(exo-N-3,5-bis(trifluoromethyl)biphenyl-norbornene-pyrrolidine)-block-poly(exo-N-(cinnamoyloxyethyl)-7-oxanorborn-5-ene-2,3-dicarboximide) (exo-PTNP-b-exo-PCONBI) were synthesized by ring-opening metathesis polymerization. The endo- or exo-PTNP served as the high dielectric functional chain, and exo-PCONBI acted as the crosslinking segment. The endo-PTNP-b-exo-PCONBI, in which endo-PTNP has a high content of trans double bond and adopts isotactic configuration, shows a dielectric constant (ε) of 15.5, whereas exo-PTNP-b-exo-PCONBI, in which exo-PTNP has 67% trans double bonds and atactic microstructure, displays relatively low ε of 7.1. The cinnamate groups in exo-PCONBI were crosslinked to form three-dimensional network by cycloaddition reaction under UV irradiation. Exposed to UV-light for 10 min, the cinnamate group in polymer films has a crosslinking conversion of 36%, as determined by UV-Vis absorption measurements. By photocrosslinking, the polymer film has an increased ε of 16.6, a dielectric loss of 0.03, an elevated glass-transition temperature of 137 °C, and an enhanced decomposition temperature of 405 °C, compared to those of polymer films without irradiation.     

Effect of donor and acceptor properties of solvents on the kinetics of photoreduction of sterically hindered <Emphasis Type="Italic">о</Emphasis>-benzoquinones

Effect of the solvent nature on the kinetics of photoreduction of 3,6-di-tert-butyl-1,2-benzoquinone and its six derivatives in the presence of N,N-dimethylaniline and 4-(N,N-dimethylamino)benzaldehyde has been investigated. It has been found that for the о-quinone—amine pair, for which the free energy change of electron transfer is ΔG_e > +0.11 eV, the rate constant of о-quinone photoreduction k_H decreases proportionally to the increase in the acceptor number of the solvent. For the о-quinone—amine pair with ΔG_e < +0.11 eV, the k_H value decreases proportionally to the increase in the donor number of the solvent. It has been established that the enhancement of the electron-acceptor properties of the solvent leads to the emergence of kinetic isotope effect for the reactant pairs of 3,6-di-tert-butyl-1,2-benzoquinone and 4,5-dimethoxy-3,6-di-tert-butyl-1,2-benzoquinone with N,N-di-methylaniline (ΔG_e = +0.11 and +0.22 eV, respectively).     

Synthesis of urethane—acrylic multi-block copolymers via electrochemically mediated ATRP

The electrochemically mediated atom transfer radical polymerisation (eATRP) of n-butyl acrylate was investigated under a variety of catalyst concentrations. Poly(n-butyl acrylate)-block-polyurethane-block-poly(n-butyl acrylate) copolymers were prepared via electrochemically mediated atom transfer radical polymerisation (eATRP) using only 7 × 10^?6 mole % of Cu^II complex. The successful chain extension and formation of penta-block copolymers confirmed the living nature of the poly(alkyl acrylates) prepared by eATRP. In this work, the tri-block and penta-block urethane-acrylate copolymers were synthesised for the first time by using tertiary bromine-terminated polyurethane macro-initiators as transitional products reacting with n-butyl acrylate, and subsequently with tert-butyl acrylate in the presence of the Cu^IIBr₂/TPMA catalyst complex. The results of ¹H NMR spectral studies support the formation of tri-block poly(n-butyl acrylate)-block-polyurethane-block-poly(n-butyl acrylate) copolymers, and penta-block poly(tert-butyl acrylate)-block-poly(n-butyl acrylate)-block-polyurethane-block-poly(n-butyl acrylate)-block-poly(tert-butyl acrylate) copolymers.     

3-(1-Methyl-1-nitroethyl-1-<Emphasis Type="Italic">ONN</Emphasis>-azoxy)-4-aminofuroxan. Synthesis and transformations of the amino group

A four-step procedure to convert 4-(1-methyl-1-nitroethyl-1-ONN-azoxy)-3-cyanofuroxan into 3-(1-methyl-1-nitroethyl-1-ONN-azoxy)-4-aminofuroxan was developed. The pathways of transformation of the amino group of the synthesized compound into N-nitramino-, N-alkyl-N-nitramino-, N,N’-methylenediamino-, N,N’-methylene-N,N’-dinitramino-, and azo groups were studied.     

Exact treatment of generalized modifications of finite-dimensional systems by the LRM approach

LRM (Low Rank Modification) is a mathematical method that produces eigenvalues and eigenstates of generalized eigenvalue equations. It is similar to the perturbation expansion in that it assumes the knowledge of the eigenvalues and eigenstates of some related (unperturbed) system. However, unlike perturbation expansion, LRM produces correct results however large the modification of the original system. LRM of finite-dimensional systems is here generalized to the combined (external and internal) modifications. Parent n-dimensional system A _n containing n eigenvalues λ _i and n eigenstates \({| {\Phi_i}\rangle}\) is described by the generalized n × n eigenvalue equation. In an external modification system A _n interacts with another ρ-dimensional system B _ρ which is situated outside the system A _n . In an internal modification relatively small σ-dimensional subsystem of the parent system A _n is modified. Modified system C _n+ρ that contains external as well as internal modifications is described by the generalized (n + ρ) × (n + ρ) eigenvalue equation. This system has (n + ρ) eigenvalues \({\varepsilon_s}\) and (n + ρ) corresponding eigenstates \({| {\Psi_s}\rangle}\) . In LRM this generalized (ρ + n) × (ρ + n) eigenvalue equation is replaced with a (nonlinear) (ρ + σ) × (ρ + σ) equation which produces all eigenvalues \({\varepsilon_s \notin \left\{ {\lambda_i}\right\}}\) and all the corresponding eigenstates \({| {\Psi_s}\rangle }\) of C _{n + ρ}. Another equation produces remaining solutions (if any) that satisfy \({\varepsilon_s \in \left\{ {\lambda_i}\right\}}\) . Those two equations produce exact solution of the modified system C _{n + ρ}. If (ρ + σ) is small with respect to n, this approach is numerically much more efficient than a standard diagonalization of the original generalized eigenvalue equation. Unlike perturbation expansion, LRM produces exact results, however large modification of the parent system A _n .     

<Emphasis Type="Italic">CrMAPK3</Emphasis> regulates the expression of iron-deficiency-responsive genes in <Emphasis Type="Italic">Chlamydomonas reinhardtii</Emphasis>

Background

Under iron-deficient conditions, Chlamydomonas exhibits high affinity for iron absorption. Nevertheless, the response, transmission, and regulation of downstream gene expression in algae cells have not to be investigated. Considering that the MAPK pathway is essential for abiotic stress responses, we determined whether this pathway is involved in iron deficiency signal transduction in Chlamydomonas.

Results

Arabidopsis MAPK gene sequences were used as entry data to search for homologous genes in Chlamydomonas reinhardtii genome database to investigate the functions of mitogen-activated protein kinase (MAPK) gene family in C. reinhardtii under iron-free conditions. Results revealed 16 C. reinhardtii MAPK genes labeled CrMAPK2–CrMAPK17 with TXY conserved domains and low homology to MAPK in yeast, Arabidopsis, and humans. The expression levels of these genes were then analyzed through qRT-PCR and exposure to high salt (150 mM NaCl), low nitrogen, or iron-free conditions. The expression levels of these genes were also subjected to adverse stress conditions. The mRNA levels of CrMAPK2, CrMAPK3, CrMAPK4, CrMAPK5, CrMAPK6, CrMAPK8, CrMAPK9, and CrMAPK11 were remarkably upregulated under iron-deficient stress. The increase in CrMAPK3 expression was 43-fold greater than that in the control. An RNA interference vector was constructed and transformed into C. reinhardtii 2A38, an algal strain with an exogenous FOX1:ARS chimeric gene, to silence CrMAPK3. After this gene was silenced, the mRNA levels and ARS activities of FOX1:ARS chimeric gene and endogenous CrFOX1 were decreased. The mRNA levels of iron-responsive genes, such as CrNRAMP2, CrATX1, CrFTR1, and CrFEA1, were also remarkably reduced.

Conclusion

CrMAPK3 regulates the expression of iron-deficiency-responsive genes in C. reinhardtii.

     

Crystal structures of a family of layered coordination polymers containing divalent metal ions (Mn<Superscript>2+</Superscript>, Co<Superscript>2+</Superscript>, Ni<Superscript>2+</Superscript> and Zn<Superscript>2+</Superscript>) and the 3-amino 4-methyl benzoate ion

The syntheses and crystal structures of the layered coordination polymers M(C₈H₈NO₂)₂ [M = Mn (1), Co (2), Ni (3) and Zn (4)] are described. These isostructural compounds contain centrosymmetric trans-MN₂O₄ octahedra as parts of infinite sheets; the ligand bonds to three adjacent metal ions in μ³-N,O,O′ mode from both its carboxylate O atoms and its amine N atom. In each case, weak intra-sheet N–H?O and C–H?O hydrogen bonds may help to consolidate the structure. Crystal data: 1, C₁₆H₁₆MnN₂O₄, M _r = 355.25, monoclinic, P2₁/c (No. 14), a = 10.6534(2) Å, b = 4.3990(1) Å, c = 15.5733(5) Å, β = 95.1827(10)°, V = 726.85(3) ų, Z = 2, R(F) = 0.026, wR(F ²) = 0.067. 2, C₁₆H₁₆CoN₂O₄, M _r = 359.24, monoclinic, P2₁/c (No. 14), a = 10.6131(10) Å, b = 4.3374(4) Å, c = 15.3556(17) Å, β = 95.473(4)°, V = 703.65(12) ų, Z = 2, R(F) = 0.041, wR(F ²) = 0.091. 3, C₁₆H₁₆N₂NiO₄, M _r = 359.02, monoclinic, P2₁/c (No. 14), a = 10.6374(4) Å, b = 4.2964(2) Å, c = 15.2827(8) Å, β = 95.9744(14)°, V = 694.66(6) ų, Z = 2, R(F) = 0.028, wR(F ²) = 0.070. 4, C₁₆H₁₆N₂O₄Zn, M _r = 365.68, monoclinic, P2₁/c (No. 14), a = 10.6385(5) Å, b = 4.2967(3) Å, c = 15.2844(8) Å, β = 95.941(3)°, V = 694.89(7) ų, Z = 2, R(F) = 0.038, wR(F ²) = 0.107.     

Cycloaminomethylation of dihydric phenols catalyzed by <Emphasis Type="Italic">d</Emphasis>- and <Emphasis Type="Italic">f</Emphasis>-metal compounds

An efficient method has been developed for the synthesis of 7,16,25-triaryl-7,8,16,17,25,26-hexahydro-6H,15H,24H-tribenzo[f,m,t][1,5,8,12,15,19,3,10,17]hexaoxatriazacyclohenicosines, 3,8-diaryl-2,3,4,7,8,9-hexahydrobenzo[1,2-e:4,3-e′]bis[1,3]oxazines, 3,9-bis(chlorophenyl)-3,4,9,10-tetrahydro-2H,8H-benzo[1,2-e:3,4-e′]bis[1,3]oxazines, and 2,9-bis(chlorophenyl)-1,2,3,8,9,10-hexahydrobenzo[1,2-e:6,5-e′]bis-[1,3]oxazines via cycloaminomethylation of pyrocatechol, resorcinol, and hydroquinone with N,N-bis(methoxymethyl) anilines in the presence of samarium catalysts.     

The response electron–electron repulsion energy and energy component analysis in CC/MBPT methods

Molecular properties are computed as responses to perturbations (energy derivatives) in coupled-cluster (CC)/many-body perturbation theory (MBPT) models. Here, the CC/MBPT energy derivative with respect to a general two-electron (2-e) perturbation is assembled from gradient theory for 2-e property evaluation, including the electron repulsion energy. The correlation energy (?E) is shown to be the sum of response kinetic (?T), electron–nuclear attraction (?V), and electron repulsion (?V _ee ) energies. Thus, evaluation of total V _ee for energy component analysis is simple: For total energy (E), total 1-e responses T and V, and nuclear–nuclear repulsion energy (V _NN ), V _ee  = E ? V _NN  ? T ? V is the true 2-e response value. Component energy analysis is illustrated in an assessment of steric repulsion in ethane’s rotational barrier. Earlier SCF-based results (Bader et al. in J Am Chem Soc 112:6530, 1990) are corroborated: The higher-energy eclipsed geometry is favored versus staggered in the two repulsion energies (V _NN and V _ee ), while decisively disfavored in electron–nuclear attraction energy (V). Our best quality calculations (CCSD/cc-pVQZ) attain practical Virial Theorem compliance (i.e., agreement among the kinetic energy, potential energy, and total energy representations) in assigning 2.70 ± 0.06 to the barrier height; ?195.80 kcal/mol is assigned to the drop in “steric” repulsion upon going to the eclipsed geometry. Steric repulsion is not responsible for any fraction of the ~3 kcal/mol barrier.     

Pyrrolidine synthons for β-lactams

Fused tricyclic aziridines, methyl rel-(2R,2aR,3R,4R,4aR,4bS)- and rel-(2S,2aR,3R,4R,4aR,4bS)-4-hydroxy-2,4a-dimethoxyhexahydro-1-oxa-2b-azacyclopropa[cd]pentalene-3-carboxylates, have been synthesized as possible precursors to β-lactams. The product structure has been determined by two-dimensional NMR techniques in combination with computational methods.     

Bimolecular reduction of 9-alkyl-3-nitrocarbazoles

Reduction of 9-alkyl-3-nitrocarbazoles (Ia–Ie) with lithium aluminium hydride gave corresponding 9,9′-dialkyl-3,3′-azocarbazoles (IIa–IIe) in moderate yield. By the action of zinc dust in alcohol and aqueous alkali on I or II, 5,13-dialkyldiindolo[3,2-a,d]phenazines (IIIa–IIId) were obtained. Parent compounds, viz. 3,3′-azocarbazole (IIf) and diindolo[3,2-a,d]phenazine (IIIf) could not be obtained in these ways. Compound IIf was obtained in Vorländer reaction and IIIf by thermal decomposition of 3-azidocarbazole. Formation of IIIa–IIId is explained as a result of ortho-benzidine rearrangement of hypothetical 9,9′-dialkyl-3,3′-hydrazocarbazoles.     

Cycloascauloside b from <Emphasis Type="Italic">Astragalus caucasicus</Emphasis>

The structure of a new cycloartane glycoside isolated from leaves of Astragalus caucasicus Pall. (Leguminosae) was elucidated using chemical transformations and spectral data. Cycloascauloside B is 20R, 25-epoxy-24S-cycloartan-3β,6α,16β,24-tetraol 3-O-[α-L-rhamnopyranosyl-(1å2)]-β-D-glucopyranoside.     

Random packing of monoatomic structures

The dependence of the first coordination number k _n on the packing factor k _y is obtained for four cubic structures: fcc, bcc, simple cubic, and diamond. The k _n (k _y ) dependence is described by a third-degree polynomial k _n = ?71.76782 + 467.78914 k _y ? 925.48451 k _y ² + 603.01146 k _y ³ with the confidence factor R _d = 1. The k _n (k _y ) function has an N loop with a maximum at k _n = 6.32; k _y = 0.454 and a minimum at k _n = 5.84; k _y = 0.573. The tangents intersect the k _n (k _y ) curve at extrema at k _y = 0.4 and k _y = 0.625. Around the N loop, i.e., at 5.84 ≤ k _n ≤ 6.32 and 0.4 ≤ k _y ≤ 0.625, two or three packing factors correspond to a certain value of the coordination number. Therefore, this range of the k _n and k _y values can be defined as a “random packing” region. Estimations presented here agree well with the results of calculations, both geometric and numerical. For monoatomic solids with the random packing parameters, the difference between the specific volumes of the solid and liquid phases is insignificant. The dilatancy effect is possible in the region where ?k _n / ?k _y ≤ 0.     

Directed Aminomethylation of Pyrrole,Indole, and Carbazole with <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N′</Emphasis>,<Emphasis Type="Italic">N′</Emphasis>-Tetramethylmethanediamine

Catalytic aminomethylation of pyrrole and indole with N,N,N′,N′-tetramethylmethanediamine in the presence of 5 mol % of ZrOCl₂·8H₂O proceeds selectively at the positions 2, 5 of pyrrole and 1, 3 of indole. Carbazole under the same conditions affords 3-formyl-9-aminomethyl derivative. The reaction in the presence of 5 mol % of K₂CO₃ occurs as monoaminomethylation: for pyrrole at the position 2, for indole at the position 3, and for carbazole at the nitrogen atom of the substrate. Water-soluble 1,1′-(1H-pyrrole-2,5-diyl)bis(N,N-dimethylmethanamine) exhibits a fungistatic activity with respect to phytopathogenic fungi Rhizoctonia solani.