Triterpene glycosides of Thalictrum squarrosum. IV. Structures of squarrosides A1, A2, B1, and B2

Four new cycloartane glycosides have been isolated from a methanolic extract ofThalictrum squarrosum Stephan ex Willd.: squarroside A1 (I) — (21R, 22S, 23R)-3β-(β-D-glucopyranosyloxy)-21α-methoxy-21,23-epoxycycloart-24-ene-22β,30-diol, C₃₀H₆₀O₁₀; squarroside A2 (II) — the (21S)-epimer of compound (I); squarroside B1 (III) (21R, 22S, 23R)-3gb-[O-α-L-rhamnopyranosyl-(1 → 6)-β-D-glucopyranosyloxy]-21α-methoxy-21,23-epoxycycloart-24-ene-22β,30-diol, C₄₃H₇₀O₁₄; and squarroside B2 (IV) — the (21S)-epimer of compound (III). The proposed structures were determined on the basis of¹H and¹³C NMR spectroscopy, FAB mass spectrometry, and chemical transformations. Irkutsk Institute of Organic Chemistry, Siberian Branch, USSR Academy of Sciences. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 516–523, July–August, 1989.     

Synthesis and structural modification of <Emphasis Type="Italic">tert</Emphasis>-butyl ester of 7α-chloro-2-(N,N-dimethylaminomethylene)-3-methyl-1,1-dioxoceph-3-em-4-carboxylic acid

The reaction of tert-butyl 7α-chloro-and 7-β-chloro-7α-isopropoxy-3-methyl-1,1-dioxoceph-3-em-4-carboxylates with the Vilsmeier reagent was carried out with introduction of N,N-dimethylaminomethylene group at position 2 in the E-and Z-isomeric forms. Prolonged treatment of tert-butyl 7α-chloro-3-methyl-2-(N,N-dimethylaminomethylene)-1,1-dioxoceph-3-em-4-carboxylate with hydroxylamine hydrochloride in acetonitrile at 40–50°C gave tert-butyl 10(S)-chloro-6-methyl-5-oxa-1,1,9-trioxo-1-thia-4,8-diazatricyclo[7,2,0,0^2,6]undecane-7(R)-carboxylate which isomerized into 1-tertbutoxycarbonylmethyl-3α-chloro-4-(5-methylisoxazole-4-sulfonyl)azetidin-2-one. In the case of tertbutyl 7β-chloro-7α-isopropoxy-3-methyl-2-(N,N-dimethylaminomethylen)-1,1-dioxoceph-3-em-4-carboxylate the analogous reaction gave tert-butyl 10β-chloro-(2S,6S,7S,10R,11R)-10α-isopropoxy-6-methyl-5-oxa-1,1,9-trioxo-1-thia-4,8-diazatricyclo[7,2,0,0^2,6]undecane-7(R)-carboxylate, the struc-ture of which was determined by 2D-NOESY two-dimensional spectroscopy. The compounds synthesized showed weak or no cytotoxic activity with respect to monolayers of cancer cells in vitro.     

Determination of the primary structure and carboxyl p<Emphasis Type="Italic">K</Emphasis><Subscript>A</Subscript>s of heparin-derived oligosaccharides by band-selective homonuclear-decoupled two-dimensional <Superscript>1</Superscript>H NMR

Determination of the structure of heparin-derived oligosaccharides by ¹H NMR is challenging because resonances for all but the anomeric protons cover less than 2 ppm. By taking advantage of increased dispersion of resonances for the anomeric H¹ protons at low pD and the superior resolution of band-selective, homonuclear-decoupled (BASHD) two-dimensional ¹H NMR, the primary structure of the heparin-derived octasaccharide ∆UA(2S)-[(1 → 4)-GlcNS(6S)-(1 → 4)-IdoA(2S)-]₃-(1 → 4)-GlcNS(6S) has been determined, where ∆UA(2S) is 2-O-sulfated ∆^4,5-unsaturated uronic acid, GlcNS(6S) is 6-O-sulfated, N-sulfated β-d-glucosamine and IdoA(2S) is 2-O-sulfated α-l-iduronic acid. The spectrum was assigned, and the sites of N- and O-sulfation and the conformation of each uronic acid residue were established, with chemical shift data obtained from BASHD-TOCSY spectra, while the sequence of the monosaccharide residues in the octasaccharide was determined from inter-residue NOEs in BASHD-NOESY spectra. Acid dissociation constants were determined for each carboxylic acid group of the octasaccharide, as well as for related tetra- and hexasaccharides, from chemical shift–pD titration curves. Chemical shift–pD titration curves were obtained for each carboxylic acid group from sub-spectra taken from BASHD-TOCSY spectra that were measured as a function of pD. The pK _As of the carboxylic acid groups of the ∆UA(2S) residues are less than those of the IdoA(2S) residues, and the pK _As of the carboxylic acid groups of the IdoA(2S) residues for a given oligosaccharide are similar in magnitude. Relative acidities of the carboxylic acid groups of each oligosaccharide were calculated from chemical shift data by a pH-independent method.     

A Validated Chiral HPLC Method for the Determination of Enantiomeric Purity of R-β-amino-β-(4-methoxyphenyl) Propionic Acid

A normal phase chiral LC method for chiral purity evaluation of β-amino-β-(4-methoxyphenyl) propionic acid was developed on donor–acceptor (pirkle) column. The chiral stationary phase used was a 250 × 4.6 mm (R, R) Whelk-01 with 5 μm particle size, which was accompanied with a 1 cm long guard column. The “hybrid” pi-electron donor–acceptor based stationary phase (R, R) Whelk-01 was found to be enantiomeric selective for (R) and (S) enantiomers of β-amino-β-(4-methoxyphenyl) propionic acid with a resolution >2.5. The concentration of 2-propanol and TFA in the mobile phase plays an important role on the chrmatographic efficiency and resolution between the enantiomers. The limit of detection and limit of quantification of (S) enantiomer was 0.3 and 1.0 μg mL^-1 for 20 μL injection volume. The percentage RSD of the peak area of six replicate injections of (S) enantiomer at LOQ concentration was 4.5. The percentage recovery of (S) enantiomer from (R) enantiomer samples ranged from 92 to 100. The test solution was observed to be stable up to 24 h after the preparation. The developed method was also checked by different analysts and on different lots of columns, reagents and it was proved to be rugged. The developed normal phase chiral LC method can be used for the determination of the enantiomeric purity of R-β-amino-β-(4-methoxyphenyl) propionic acid.     

Synthesis from (+)-α-pinene of optically active macrocycles containing cyclobutane,ester, azine,or hydrazide groups

Optically active symmetric macrocyclic diesterazines and diesterdihydrazides were synthesized efficiently from the available natural monoterpene (+)-α-pinene (de 50%) using a [2+1]-reaction of 1′-[(1S,3S)-3-(2hydroxyethyl)-2,2-dimethylcyclobutyl]ethanone and glutaric and adipic acid chlorides followed by [1+1]condensation of the intermediate diketodiesters with hydrazine hydrate or glutaric acid dihydrazide.     

Preparation of enantiomeric pure (?)-(3R,4S)-1-benzyl-3,4-epoxypiperidine and enriched (?)-(R)-1-Benzyl-3-hydroxy-1,2,3,6-tetrahydropyridine by kinetic separation of (±)-1-benzyl-3,4-epoxypiperidine under the action of chiral lithium amides

Enantiomeric pure (−)-(3R,4S)-1-benzyl-3,4-epoxypiperidine and (−)-(R)-1-benzyl-3-hydroxy-1,2,3,6-tetrahydropyridine with enantiomeric excess 61.9% were obtained by kinetic separation of (±)-1-benzyl-3,4-epoxypiperidine under the action of lithium salt (+)-(S)-2-[(pyrrolidin-1-yl)methyl]pyrrolidine. The sterical direction of the kinetic separation of (±)-1-benzyl-3,4-epoxypiperidine and absolute configurations of the target products were established. Original Russian Text ? G.V. Grishina, I.S. Veselov, V.A. Davankov, M.M. Il’in, N.S. Zefirov, 2008, published in Zhurnal Organicheskoi Khimii, 2008, Vol. 44, No. 2, pp. 287–291.     

A New Calamenene Sesquiterpene Glycoside from the Bark of Thespesia populnea

Chemistry of Natural Compounds - One new calamenene sesquiterpene glycoside, (1R,2R,3S,4S)-4-isopropyl-1,6-dimethyl-1,2,3,4- tetrahydronaphthalene-2,7-diol 3-O-β-D-glucopyranoside (1), along...     

Structural and mechanistic information on the nitrosation of model Fe(II) complexes containing a biomimetic S4N chelate

In order to provide insight into the reaction pathways of nitrogen oxide redox species with [Fe-S] models that may parallel those existing in biology, the reactivity of the iron-sulfur species, {[Fe(II)(S(4)NEt(2)N)]}(2) (1) and [Fe(II)(CH(3)CN)(S(4)NEt(2)N)] (2), where (S(4)NEt(2)N)(2-) = 2,6-bis(2-mercaptophenylthiomethyl)-4-diethylaminopyridine(2-), towards NO(+) (nitrosation) has been studied mechanistically in acetonitrile and compared with the corresponding reactions with NO (nitrosylation). For the nitrosation of 1, the reaction takes place in two steps that correspond to the nitrosation of the mononuclear (2) and dinuclear (1) complexes, respectively. For the corresponding carbonyl complex [Fe(II)(CO)(S(4)NEt(2)N)] (3), the nitrosation reaction occurs in a single step. The relative reactivity of the iron-sulfur species is approximately (1)/(2)/(3) = 1/20/10. Activation parameters for the nitrosation of 1 (ΔH(#) = 27 ± 1 kJ mol(-1), ΔS(#) = -111 ± 2 J K(-1) mol(-1), and ΔV(#) = -19 ± 2 cm(3) mol(-1)), 2 (ΔH(#) = 46 ± 2 kJ mol(-1), ΔS(#) = -22 ± 7 J K(-1) mol(-1), and ΔV(#) = -9.7 ± 0.4 cm(3) mol(-1)) and 3 (ΔH(#) = 38 ± 1 kJ mol(-1), ΔS(#) = -44 ± 4 J K(-1) mol(-1), and ΔV(#) = -7.8 ± 0.3 cm(3) mol(-1)) were determined from variable temperature and pressure studies. The significantly negative ΔS(#) and ΔV(#) values found for the nitrosation reactions are consistent with an associative mechanism. A comparative study of the reactivity of the iron-sulfur species 1 to 3 towards NO(+) and NO is presented.     

Chirally N-Substituted Indole-2-carbaldehydes. Preparation and Use in Asymmetric Synthesis

A simple method is proposed for the synthesis of optically active indole-2-carbaldehydes via alkylation of 2-cyanoindole by optically active secondary alcohols and subsequent reduction of the cyano group to an aldehyde. Reaction of the aldehydes obtained with aromatic amines gave imines whose reaction with the Danishefsky diene was studied. The structure of the major diastereomer of (2R′)-1-phenyl-2-[1-((1R′)-1-phenylethyl)indol-2-yl]-1,2,3,4-tetrahydropyridine-4-one and minor diastereomer (2S)-2-[1-((1S)-2-methoxy-1-phenylethyl)indol-2-yl]-1-phenyl-1,2,3,4-tetrahydropyridine-4-one respectively were established by X-ray analysis. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1540–1550, October, 2005.     

Diastereoselective reaction of (1S,2S)-2-amino-1-(4-nitrophenyl)-1,3-propanediol with aromatic aldehydes. Synthesis of (1R,2R,4S,5S,8S)-2,8-diaryl-4-(4-nitrophenyl)-1-aza-3,7-dioxabicyclo[3.3.0]octanes

We have synthesized a series of (1R,2R,4S,5S,8S)-2,8-diaryl-4-(4-nitrophenyl)-1-aza-3,7-dioxabicyclo[3.3.0]octanes as a result of reaction of (1S,2S)-2-amino-1-(4-nitrophenyl)-1,3-propanediol with aromatic aldehydes. The structure of the compounds obtained was established on the basis of ¹H NMR data. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 757–763, May, 2006.     

共轭微孔聚合物热解制备氮、硫杂原子硬炭及其储锂性能

选取溴代噻唑和三乙炔基苯为单体,利用聚合反应自下而上构建含噻唑共轭微孔聚合物(NSCMP),通过热解和KOH活化热解NSCMP制备了氮、硫杂原子硬炭(NSHC)和活化NSHC(KNSHC)。利用扫描电子显微镜、能量色散谱、氮气吸附-脱附和恒流充放电等表征2个样品的结构与电化学性能。研究表明KNSHC中N和S的质量分数分别为10.42%和2.23%,KNSHC比表面积高达2 140 m²·g^-1。在0.2 A·g^-1电流密度下循环500次后KNSHC和NSHC的可逆比容量分别为946.2和493.7 mAh·g^-1。KNSHC的优异电化学性能归因于其独特的孔结构和氮、硫杂原子的协同作用。     

Palladium(II) complexes with 1-allyl-3-(2-pyridyl)thiourea: Synthesis and spectroscopic characterization

New Pd(II) complexes with 1-allyl-3-(2-pyridyl)thiourea (APTU) of the formulas [Pd(C₉H₁₁N₃S)Cl₂] (I) and [Pd(C₉H₁₁N₃S)₂]Cl₂ (II) were obtained and examined by UV-Vis, IR, and 1H NMR spectroscopy. The conditions for the complexation reactions were optimized. The instability constants and molar absorption coefficients of these complexes were calculated. Comparison of the characteristic bands in the UV-Vis and IR spectra of the complexes and free APTU revealed that the ligand in both complexes is coordinated to the metal atom in the thione form in the bidentate chelating mode through the S atom of the thiourea group and the pyridine N atom. In the UV-Vis spectra of the complexes, the charge transfer bands (π → π* Py) and n → π* (C=N_Py), (C=S) experience hypsochromic shifts by 450–470 cm⁻¹ caused by the coordination of APTU to the metal ion, which gives rise to ligand-metal charge-transfer bands (C=N_Py → Pd, n → π* (C=S)) and (SPd). The protons in the 6-, 4-, and 3-positions of the pyridine ring and the thiourea NH proton in the chelate ring are most sensitive to the complexation.     

π-complexes of monoanionic carborane ligand [9-(Me2S)-7,8-C2B9H10]− with [η-C5R5Fe]+ (R=H, Me) and [η-C4Me4Co]+ cationic fragments

Compounds (η-C₅R₅)Fe[η-9-(Me₂S)-7,8-C₂B₉H₁₀] (R=H, Me) and (η-C₄Me₄)Co[η-9-(Me₂S)-7,8-C₂B₉H₁₀] were synthesized by the reactions of Na[9-(Me₂S)-7,8-C₂B₉H₁₀] with complexes [(η-C₅H₅)Fe(MeCN)₃]PF₆, [(η-C₅Me₅)Fe(MeCN)₃]BF₄, and [(η-C₄Me₄)Co(MeCN)₃]PF₆, respectively. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 177–179, January, 1999.     

Synthesis of 2-oxazolidinones from (1S,2S)-2-amino-1-(4-nitrophenyl)-1,3-propanediol

A series of isomeric 2-oxazolidinones has been synthesized from (1S, 2S)-2-amino-1-(4-nitrophenyl)-1,3-propanediol. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 579–584, April, 2006.     

Steroids of the spirostan and furostan series from nolina microcarpa III. Structure of nolinofurosides G and H

Two new glycosides which have been called nolinofurosides G(I) and H(III), have been isolated from the leaves ofNolina microcarpa. Nolinofuroside G is the sodium salt of 26-β-D-glucofuranosyloxy-(25S)-furost-5,20(22)-diene-1β, 3β-diol 1-sulfate, and nolinofuroside H is the sodium salt of 1-β-D-fucopyranosyloxy-26-β-D-glucopyranosyloxy-(25S)-furost-5,20(22)-dinen-1β-3β-ol 3-sulfate. M. V. Frunze Simferopol' State University. Institute of the Chemistry of Plant Substances, Uzbek. Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 801–806, November–December, 1991.     

Bicymantrenyl chemistry

Planar chiral 2- and 3-bicymantrenylcarbaldehydes can be resolved to enantiomers through Schiff's bases with (S)-(−)-α-phenylethylamine. Optically active derivatives of bicymantrenyl with Me and CH₂OH substituents were synthesized from (−)-3-bicymantrenylcarbaldehyde. The absolute configuration of Schiff's base obtained from (+)-3-bicymantrenylcarbaldehyde was determined by X-ray diffraction analysis. For Part 3, see Ref. 1. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 158–162, January, 1997.     

Cyclothiomethylation of heterochain α,ω-diamines with formaldehyde and H<Subscript>2</Subscript>S

Cyclothiomethylation was performed of heterochain (O, S-S, NH) α,ω-diamines with formaldehyde and H₂S in aqueous medium at 20–60°C to obtain new α,ω-bis(1,3,5-dithiazinanes). The cyclocondensation of N-(3-aminopropyl)butane-1,4-diamine (spermidine), formaldehyde, and H₂S proceeds efficiently in the medium of BuOH-H₂O at 0°C and leads to the formation of previously unknown O,S-containing macroheterocycle, 1,7-dioxa-3,5,9,11-tetrathiacyclododecane. A fungicidal activity was found in 5,5′-(3,6-dioxaoctane-1,8-diyl)bis-1,3,5-dithiazinane with respect to microscopic fungi affecting agriculture.     

DNA-binding and cleavage studies of chiral Mn(III) salen complexes

Chiral bridge-substituted manganese(III) complexes of N,N′-bis-(2-hydroxynaphthalene-1-carbaldehyde)-(1R,2R)-(−)-diaminocyclohexane and N,N′-bis-(2-hydroxynaphthalene-1-carbaldehyde)-(1S,2S)-(+)-diaminocyclohexane have been synthesized. The interaction of these complexes with calf thymus DNA(CT-DNA) was investigated by spectroscopic, thermal denaturation studies, circular dichroism (CD), and viscosity measurements. Results of spectroscopic and viscosity measurements suggest that the two complexes bind to DNA via an intercalative mode and display enantioselectivity. These Mn(III) complexes have been found to promote the cleavage of plasmid DNA pBR322 in the presence of H₂O₂.     

Synthesis of flavonoid-type compounds from methyl dehydroabietates

The synthesis of new flavone-type compounds bearing several chiral centres, 12- and 14-(2′-chromonyl)dehydroabietates, are reported. This synthesis started from the aldol condensation of methyl 12- and 14-formyldehydroabietates with 2′-hydroxyacetophenones in order to prepare the corresponding chalcone-type compounds, which were then transformed in the expected flavone-type compounds by cyclodehydrogenation with DMSO and a catalytic amount of iodine. All compounds were exhaustively characterised by NMR and MS techniques. Present address: Silvia M. C. S. Monteiro, Environment Department, Polytechnic Institute of Leiria, 2411–901 Leiria, Portugal. Correspondence: José A. S. Cavaleiro, Chemistry Department, University of Aveiro, 3810-193 Aveiro, Portugal.