Furostanol saponins with inhibitory action against COX-2 production from Tupistra chinensis rhizomes

Two furostanol saponins were obtained from the n-butanol fraction of methanol extract from Tupistra chinensis rhizomes,a folk medicine of Shennongjia Forest District of Hubei Province.Their structures were determined as (25S)-26-O-(β-D-glucopyranosyl)- furost-1β,3β,22α,26-tetrol-3-O-β-D-glucopyranosyl-(1→4)-β-D-glucopyranosyl-(1→2)-β-D-glucopyranoside (1) and (25R)- 26-O-(β-D-glucopyranosyl)-furost-1β,3β22α,26-tetrol 3-O-β-D-glucopyranosyl-(1→4)-β-D-glucopyranosyl-(1→2)-β-D-glu- copyranoside (2),on basis of chemical and spectroscopic evidences.1 and 2 displayed marked inhibitory action towards COX-2 production in macrophages of the rat abdomen induced by LPS at 20μg/mL.     

Two new saponins from Anemarrhena asphodeloides Bge.

Two new saponins 3-O-β-D-glucopyranosyl (1→2)-β-D-mannopyranosyl sarsasapogenin, named timosaponin A IV(1) and (5β, 25S)-26-O-β-D-glucopyranosyl-furost-20(22)-en-3,26-diol-3-O-β-D-glucopyranosyl (1→4) glucopyranosyl (1→2)-β-D-galacopyranoside, named timosaponin B IV(2), were isolated by silica gel column chromatography and preparative HPLC from Anemarrhena asphodeloides Bge. Their structures were elucidated by chemical characters and spectroscopic analysis.     

Two acridones and two coumarins from the roots of Paramignya trimera

Two acridones, paratrimerins C (1) and D (2), and two coumarins, paratrimerins E (3) and F (4), were isolated from the CHCl₃ and EtOAc extracts of Paramignya trimera (Rutaceae), together with twelve known compounds (5–16). Their structures were elucidated on the basis of spectroscopic data. All isolated compounds possessed significant α-glucosidase inhibitory activity in a concentration-dependent manner, and showed more potent inhibitory activity, with IC₅₀ values ranging from 14.6 to 112.2 μM, than the positive control acarbose (IC₅₀, 214.5 μM). The biosynthesis of the isolated coumarins and acridones was proposed.     

Synthesis,biological evaluation and Structure Activity Relationships (SARs) study of 8-(substituted)aryloxycaffeine

A series of 8-(substituted)aryloxycaffeine were prepared from 8-bromocaffeine and (substituted)phenols by modified Ullmann reaction. In vitro antibacterial activity, inhibitory activity on topoisomerase II and pharmacological activities were evaluated for the synthesized 8-(substituted)aryloxycaffeine. Among the synthesized compounds, 8-(5-chloropyridin-3-yloxy)caffeine (3k) showed strong inhibitory activity (MIC = 15.6 μg/mL) against the tested gram negative (−) bacteria Salmonella enteritidis. 8-(quinolin-8-yloxy)caffeine (3g) showed the strongest inhibitory activity against topoisomerase II. And the compounds 8-(6-methylpyridin-2-yloxy)caffeine (3j) and 8-(3-chloro-6-(trifluoromethyl)pyridin-2-yloxy)caffeine (3m) showed analgesic effect without the central nervous system stimulation.     

Adduct formation of [(η7-C7H7)Hf(η5-C5H5)] with isocyanides,phosphines and N-heterocyclic carbenes: An experimental and theoretical study

The reactions of [(η⁷-C₇H₇)Hf(η⁵-C₅H₅)] (1b) with the two-electron donor ligands tert-butyl isocyanide (tBuNC), 2,6-dimethylphenyl isocyanide (XyNC), 1,3,4,5-tetramethylimidazolin-2-ylidene (IMe) and trimethylphosphine (PMe₃) are reported. The 1:1 complexes [(η⁷-C₇H₇)Hf(η⁵-C₅H₅)L] (2b, L = tBuNC; 3b, L = XyNC; 4b, L = IMe, 5b, L = PMe₃) have been isolated in crystalline form, and their molecular structures have been determined by X-ray diffraction analyses. The stabilities of these hafnium complexes were probed via spectroscopic and theoretical methods, and the results were compared to those previously reported for the corresponding zirconium complexes derived from [(η⁷-C₇H₇)Zr(η⁵-C₅H₅)] (1a). The X-ray crystal structure of the PMe₃ adduct [(η⁷-C₇H₇)Zr(η⁵-C₅H₅)(PMe₃)] (5a) was also established.     

A new sesquiterpene from Caragana intermediia

A new alloaromadendrane-type sesquiterpene,(-)-alloaromadendrane-3β,9β-diol(1),has been isolated from the aerial part of Caragana intermediia.The structure of (-)-alloaromadendrane-3β,9β-diol(1)was established by spectroscopic methods, including X-ray analysis that provided its relative stereochemistry.Bioassay showed that (-)-alloaromadendrane-3β,9β-diol (1)possesses anti-pyricularia oryzae P-2b activity with MIC value of 10μg/mL.     

Synthesis and crystal structure of (S)-pindolol

Racemic 3-(4-indolyloxy)-1,2-propanediol 2 has been effectively resolved into (S)- and (R)-enantiomers by a preferential crystallization procedure. Non-racemic (S)-2 was converted into (S)-4-(2,3-epoxypropoxy)-1H-indole (S)-4 via a Mitsunobu reaction and then into (S)-pindolol (S)-1. The crystalline (S)-1 was studied by single crystal X-ray diffraction. A large number of symmetry independent molecules (Z′ = 6) led to a weakening of the system of strong intermolecular hydrogen bonds, which combined with a loose packing (PI = 64.6%), may be the cause of the abnormally low melting point of (S)-1 as compared with rac-1.     

Synthesis,crystal structure and thermal behaviour of [La(hfa)3(Phen)2] (hfa = hexafluoroacetylacetonate,Phen = o-phenanthroline)

The mixed ligand complex [La(hfa)₃(Phen)₂] (I) was obtained by the interaction of La(hfa)₃ and Phen; its composition does not depend on the stoichiometry of the reagents. According to the X-ray single crystal analysis data, complex I crystallizes in the monoclinic space group P2₁/n, with a = 13.583(3) Å, b = 16.959(3) Å, c = 18.860(4) Å, β = 94.71(3)° and Z = 4. The structure of I consists of isolated mononuclear molecules, the coordination number of La being 10. Thermal behaviour and composition of the vapor phase have been studied for I by thermal analysis and mass-spectrometry using a Knudsen cell. The mixed ligand complex I was found to sublime congruently in the temperature range 370–460 K: [La(hfa)₃(Phen)₂]_(s) = [La(hfa)₃(Phen)]_(g) + Phen_(g), Δ_rH⁰(T) = 316.2 ± 1.8 kJ/mol.     

Synthesis and molecular modeling study of Cu(Ⅱ) complexes derived from 2-(diphenylmethylene)hydrazinecarbothioamide derivatives with cholinesterase inhibitory activities

Thiosemicarbazones of 2-amino-5-chlorobenzophenone and 3-aminobenzophenone（L¹-L⁴） have been synthesized and their Cu（Ⅱ） complexes（1-4） were afforded via coordination with cupric chloride.All these compounds were characterized by UV-vis and IR spectroscopy together with CHN elemental analysis.NMR spectroscopy was also applied to characterize the ligands.In vitro chohnesterase inhibitory assays for the complexes（1-4） showed IC₅₀ values less than 10μmol/L,with complex 1 exhibiting the most activity,IC₅₀=2.15μmol/L and 2.16μmol/L for AChE and BuChE,respectively. Molecular modeling simulation revealed the binding interaction template for complex 1 with the AChE and BuChE receptors.In DPPH assay,the complexes also showed more in vitro antioxidant activities in comparison to their parent ligands.     

Nodupetide,a potent insecticide and antimicrobial from Nodulisporium sp. associated with Riptortus pedestris

Nodupetide (1), a new cyclodepsipeptide unique in its incorporation of a 3-hydroxy-4-methylhexanoic acid (HMHA) derived motif, was discovered from Nodulisporium sp. IFB-A163, a fungus residing in the insect (Riptortus pedestris) gut. The nodupetide structure was elucidated by its MS/MS and 2D NMR spectra, and its absolute configuration by the X-ray crystallography and modified Marfey’s method. Nodupetide is insecticidal against rice brown planthopper (Nilaparvata lugens) with an LD₅₀ value of 70 ng/larva, and inhibitory towards the drug-resistant human pathogenic bacterium Pseudomonas aeruginosa with its MIC value (5.0 μM) comparable to that (3.2 μM) of ciprofloxacin, a prescribed antibacterial agent co-assayed equally.     

α-Glucosidase inhibitors from the stem of Mangifera reba

Two new neolignans, named rebaneolignan A (1) and B (2), were isolated from the stem of Mangifera reba (Anacardiaceae), together with six known compounds (3–8). Their structures were elucidated on the basis of NMR spectroscopic analysis and the absolute configurations of 1 and 2 were determined by NOESY and CD data. All isolated compounds were found to possess more potent inhibitory activity, with IC₅₀ values ranging from 28.5 to 162.8 µM, than the positive control acarbose (IC₅₀, 214.5 µM). Plausible biosynthetic pathways for the formation of 1 and 2 were proposed based on the oxidative β-5′ coupling reactions.     

Two new tetrahydrofuran derivatives from the fungus Mucor spp. SNB-VECD11D isolated from the Chrysomelidae Acalymma bivittula

Two new tetrahydrofuran derivatives, mucorinic acids A (1) and B (2) as well as the three known secondary metabolites dehydroabietic acid (3), Δ8-dihydroabietic acid (4) and 8-pimarenic acid (5) were isolated from a solid culture of the fungus Mucor spp. isolated on insect Acalymma bivittula. The structure of these compounds was elucidated by analysis of NMR and MS spectroscopic data. Compounds were tested in antimicrobial and insecticidal assays. Dehydroabietic acid exhibited moderate larvicidal activity on Aedes aegypti larvae with 65% mortality at 10 ppm. Both new compounds 1 and 2 showed interesting antibacterial activity on Staphylococcus aureus and methicillin resistant S. aureus with MIC values in the 8–16 μg/ml.     

Lipase-catalyzed kinetic and dynamic kinetic resolution of 1,2,3,4-tetrahydroisoquinoline-1-carboxylic acid

A dynamic kinetic resolution method for the preparation of enantiopure 1,2,3,4-tetrahydroisoquinoline-1-carboxylic acid (R)-2 was developed involving the CAL-B-catalyzed enantioselective hydrolysis of the corresponding ethyl ester (±)-1 in toluene/acetonitrile (4:1) containing 1 equiv of added water and 0.25 equiv of dipropylamine. This method allowed the preparation of (R)-2 (ee = 96%) with 80% isolated yield. The kinetic resolution of (±)-1 in diisopropyl ether at 3 °C afforded both enantiomers with ee ⩾92%.     

Phosphanes with bulky oligosilyl substituents

By reaction of dichloroheptasilane [(SiMe₃)₂MeSi]₂SiCl₂ with lithiumphosphanides LiPHR, the silylphosphanes [(SiMe₃)₂MeSi]₂SiClPHR with R = 2, 4, 6-tri-tert-butylphenyl ( = supermesityl, Mes1) (1) and Si(SiMe₃)₃ ( = hypersilyl, Hyp) (2) were prepared. Both compounds were characterized with X-ray diffraction, multinuclear NMR spectroscopy and elemental analysis. Compound 1 did not react with n-BuLi, but only with a large excess of tert-BuLi. Phosphasilene [(SiMe₃)₂MeSi]₂SiPMes¹ could be identified by a ³¹P NMR signal at +346 ppm. All attempts to separate it from the reaction mixture failed due to many by-products which had formed through SiSi and SiP bond cleavage. Lithiation of 2 was possible with 4.2 equiv. of tert-BuLi, and crystals of the lithiumphosphanide [(SiMe₃)₂MeSi]₂SiClPLiHyp (3) could be obtained from THF, albeit in a quality not sufficient for X-ray diffraction. All attempts to achieve LiCl elimination and formation of the phosphasilene [(SiMe₃)₂MeSi]₂SiPSi(SiMe₃)₃ failed due to the unusual stability of the lithiumphosphanide. Prolongued refluxing in toluene (110 °C) only led to complete loss of coordinated THF, and ³¹P⁷Li spin spin coupling could be observed in the ³¹P NMR spectrum (¹J_PLi = 84 Hz).Reaction of potassium phosphanide [(SiMe₃)₃Si]SiMe₃PK with SiCl₄ led to the formation of [(SiMe₃)₃Si](SiMe₃)P(SiCl₃) (4), which could be successfully characterized with X-ray diffraction and multinuclear NMR spectroscopy. SiP bond lengths vary between 218 pm (SiCl₃) and 230 pm (hypersilyl). Despite these differences, ³¹P²⁹Si coupling constants are nearly identical (92.4 Hz and 85.5 Hz, respectively).     

Synthesis of the (1S,2S)- and (1R,2S)-stereoisomers of the respective E- and Z-isomers of ethyl 4-[(2-hydroxycyclohexyl)methyl]phenoxy-3-methyl-2-butenoate using yeast whole cell bioreduction of the parent ketones

Saccharomyces cerevisiae, strain DBM 2115, was successfully employed in the reduction of the separated Z- and E-isomers of ethyl 4-[(2-oxocyclohexyl)methyl]phenoxy-3-methyl-2-butenoates 1 and 2, in order to prepare the (1S,2S)- and (1R,2S)-enantiomers of the corresponding ethyl 4-[(2-hydroxycyclohexyl)methyl]phenoxy-3-methyl-2-butenoates 3–6. The products were obtained with the required absolute configuration: (1S,2S)-3 (ee = 98%; yield 48%), (1R,2S)-4 (ee = >99%; yield 45%), (1S,2S)-5 (ee = 98.5%; yield 47%), and (1R,2S)-6 (ee = >99%; chemical yield 44%).     

Enantioselective self-assembly,crystallographic structure and magnetic properties of the two enantiomers of the optically active canted antiferromagnet [Ru(bpy)3][Mn2(ox)3]

The two enantiomers of [Ru(bpy)₃][Mn₂(ox)₃] (bpy = 2,2′-bipyridine, ox = oxalate), namely [(Δ)-Ru(bpy)₃][(Δ)-Mn₂(ox)₃], (Δ-1) and [(Λ)-Ru(bpy)₃][(Λ)-Mn₂(ox)₃], (Λ-1), were obtained as single crystals using [(Δ)-Ru(bpy)₃]²⁺ and [(Λ)-Ru(bpy)₃]²⁺, respectively, as a chiral templating cation. Their structures were determined by single-crystal X-ray diffraction. The compounds crystallise in the enantiomeric chiral cubic space groups, P4₃32 (Δ-1) and P4₁32 (Λ-1), with a = 15.492(2) and 15.507(2) Å, respectively (Z = 4). Both structures include a three-dimensional 10-gon 3-connected (10,3) anionic network wrapped around the [Ru(bpy)₃]²⁺ cations. In both crystalline enantiomers, the resolved ruthenium template cation imposes both the topology and the absolute configuration of all the metal centres. The thermal variation of the magnetic susceptibility, measured on Δ-1 and Λ-1 crystals, reveals an antiferromagnetic coupling between the oxalate-bridged manganese ions in the paramagnetic region characterised by a negative Weiss constant Θ = −35 K. Below T_N = 13 K, Δ-1 and Λ-1 exhibit a canted antiferromagnetic order.     

Stereospecific polymerization of propylene with group 4 ansa-fluorenylamidodimethyl complexes

Group 4 [η¹:η³-tert-butyl(dimethylfluorenylsilyl)amido]dimethyl complexes [t-BuNSiMe₂Flu]MMe₂ (M = Ti, 1; Zr, 2; Hf, 3) were synthesized in a one-pot synthesis starting from the ligand, MeLi and MCl₄ (M = Ti, Zr, Hf), respectively. The structures of these complexes were determined by X-ray crystallography and the results obtained revealed that the fluorenyl ligand coordinates to center metal in a η³-manner irrespective of center metal employed. Propylene polymerization was conducted at 0 or 20 °C in toluene by 1–3 combined with dried methylaluminoxane (MAO), which was prepared from the toluene solutions of MAO by removing free trialkylaluminiums, and HNMe₂PhB(C₆F₅)₄ in the presence of triisobutylaluminium. The 1–dried MAO system gave the polymer with syndiotactic triad (rr) of 63% at 0 °C, whereas 2 and 3 did not give any polymer in the same conditions. The 2–dried MAO system gave the polymer with the highest syndiotacticity (rr = 97%) at 20 °C, although the activity was low. The 3–dried MAO system did not give any polymer even at 20 °C. When HNMe₂PhB(C₆F₅)₄ was used in place of dried MAO at 20 °C, 1 gave almost atactic polymer, while 2 and 3 gave highly syndiotactic one (rr > 90%). These results indicate that the catalytic performance strongly depended on the center metal of the ansa-fluorenylamidodimethyl complexes as well as cocatalysts employed.     

Pseudoferic acids A–C,three novel triterpenoids from the root bark of Pseudolarix kaempferi

Three novel triterpenoids, pseudoferic acids A and B (1 and 2) possessed a unique 16,24-cyclo-26-norlanostane skeleton, and pseudoferic acid C (3) featured a cis-fused D/E-ring system, were isolated from the root bark of Pseudolarix kaempferi. Their structures were elucidated on the basis of extensive spectroscopic analysis. Compounds 2 and 3 exhibited weak inhibitory activities against 11β-HSD1 (11β-hydroxysteroid dehydrogenase 1) with IC₅₀ values of 0.44 (mouse 11β-HSD1) and 0.75 μM (human 11β-HSD1), respectively.     

O,O-Monochelate complexes of silicon and germanium halides: The derivatives of l-mandelic N,N-dimethylamide

Reactions of O-trimethylsilyl-l-mandelic N,N-dimethylamide (1) with tetrachlorosilane and tetrachlorogermane lead to O,O-monochelate complexes, [1-(dimethylcarbamoyl)-1-phenylmethoxy]trichlorosilane (2) and [1-(dimethylcarbamoyl)-1-phenylmethoxy]trichlorogermane (3). Pentacoordination of silicon and germanium in these complexes was confirmed by X-ray studies.X-ray data show that the Si and Ge atoms in 2 and 3 have TBP environments where the ether oxygen and two halogens are equatorial while the third halogen and the amide oxygen occupy axial positions. The axial O–M and Cl–M (M = Si, Ge) distances are somewhat longer than those in similar compounds of tetracoordinate silicon and germanium.Intramolecular coordination in compounds 1–3 and relative stabilities of different conformations of their molecules were studied by quantum-chemical calculations.     

Palladium(II) complexes with the new P,N-type ligand (2-oxazoline-2-ylmethyl)di-isopropylphosphine as intermediates in CO/ethylene or CO/methyl acrylate insertion

The ligand (i-Pr)₂PCH₂(oxazoline) (1a), of the P,N-donor type, was reacted with [PdMeCl(COD)] to yield the square planar methylpalladium(II) complex [PdClMe(P,N)] (P,N = 1a) (2a), from which the complex [PdMe(P,N)OTf] (OTf = OSO₂CF₃) (3a) was obtained by AgOTf-promoted chloride abstraction. The alkyl complexes

(P,N = 1a) (5a, R = H; 7a, R = C(O)OMe) have been isolated from the initial CO/ethylene or CO/methyl acrylate insertion steps into the Pd–Me bond of 3a, respectively, and spectroscopically characterized. Complexes 2a, 3a and 7a have been fully characterized by single crystal X-ray diffraction. Complex 7a is still a rare example of a structurally characterized CO/methyl acrylate stepwise insertion product. These complexes are relevant to the alternating copolymerization of olefins and carbon monoxide catalyzed by palladium complexes. In addition, the centrosymmetric dinuclear complex trans-[Pd(μ-Cl){(i-Pr)₂PCH₂(oxazoline)}]₂(OTf)₂ (6) has been obtained and characterized by X-ray diffraction; it appears to be the first dinuclear complex of the type [Pd(μ-Cl)(P,N)]₂ to be characterized by X-ray crystallography.

Résumé

Le ligand (i-Pr)₂PCH₂(oxazoline) (1a), de type donneur P,N, réagit avec [PdClMe(COD)] pour former le complexe plan carré méthylpalladium(II) [PdClMe(P,N)] (P,N = 1a) (2a), à partir duquel le complexe [PdMe(P,N)OTf] (OTf = OSO₂CF₃) (3a) a été obtenu par abstraction de chlorure à l'aide de AgOTf. Les complexes alkyles

(P,N = 1a) (5a, R = H; 7a, R = C(O)OMe), ont été isolés lors des premières étapes d'insertion de CO/éthylène ou de CO/acrylate de méthyle, respectivement, dans la liaison Pd–Me de 3a, et caractérisés par méthodes spectroscopiques. Les complexes 2a, 3a et 7a ont été complètement caractérisés par diffraction des rayons X sur monocristal. Le complexe 7a est un exemple encore rare de produit d'insertion par étapes de CO/acrylate de méthyle qui ait été caractérisé structuralement. Ces complexes sont pertinents pour la copolymérisation alternée d'oléfines et de monoxyde de carbone catalysée par les complexes du palladium. En outre, le complexe dinucléaire centrosymétrique trans-[Pd(μ-Cl){(i-Pr)₂PCH₂(oxazoline)}]₂(OTf)₂ (6) a été obtenu et caractérisé par diffraction des rayons X; il s'agit du premier complexe dinucléaire de type [Pd(μ-Cl)(P,N)]₂ à être caractérisé par diffraction des rayons X.