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1.
The absolute configuration at C-12 of pittosporatobiraside A and B isolated from the leaves of Pittosporum tobira was determined to be S on the basis of the exciton chirality of their dibenzoate derivative. The structures of the two glycosides were thus established to be (1S,9S,10S,11S,12S,14R,16R)-12-[(Z)-2-methyl-1-oxo-2-butenyl]-6,14-dimethyl-2-methylene-9-(1-methylethyl)-15,17-dioxatricyclo[8.7.0.011,16]heptadec-5-en-13-one and (1S,9S,10S,11S,12S,14R,16R)-12-(3-methyl-1-oxo-2-butenyl)-6,14-dimethyl-2-methylene-9-(1-methylethyl)-15,17-dioxatricyclo [8.7.0.011,16]heptadec-5-en-13-one, respectively. 相似文献
2.
A. Gilberto Ferreira Joo B. Fernandes Paulo C. Vieira Otto R. Gottlieb Hugo E. Gottlieb 《Phytochemistry》1995,40(6):1723-1728
The seeds of Otoba parvifolia contain three novel compounds apparently derived from homogentisic acid, rel-(1′R,5′R)-2-(1′-farnesyl-5′-hydroxy-2′-oxocyclohex-3′-en-1′-yl)-acetic acid and its acetate as well as rel-(1′R,4′S,5′R)-2-(1′-farnesyl-4′,5′-dihydroxy-2′-oxocyclohexan-1′-yl)-acetic acid δ-lactone. The structure of an additional isolate, previously described as 2-(1′-farnesyl-2′-hydroxy-5′-oxocyclohex-3′-en-1′-yl)-acetic acid γ-lactone was revised to rel-(1′R,5′R)-2-(1′-farnesyl-5′-hydroxy-2′-oxocyclohex-3′-en-1′-yl)-acetic acid δ-lactone. 相似文献
3.
Carmenza Duque Jorge Rojas Sven Zea Alejandro J. Roccatagliata Marta S. Maier Alicia M. Seldes 《Biochemical Systematics and Ecology》1997,25(8):775-778
Sterol compositions of the cold water ophiuroids Ophioplocus januarii and Ophionotus victoriae and of the tropical ophiuroids Ophiocoma echinata and Ophiocoma wendtii are reported. The four sterol mixtures contain Δ5 mono- and di-unsaturated common 3β-hydroxy-sterols. Ophioplocus januarii and O. victoriae contain 24-methylcholesta-5,24(28)-dien-3β-ol and 24ζ-ethylcholesta-5,24(28)-dien-3β-ol in higher abundance than in O. echinata. These sterols were not found in O. wendtii. An interesting finding is the presence of Δ5,24(28)-24-n-propylidenecholesterol in 7.6% in Ophionotus victoriae. 相似文献
4.
The synthesis and NMDA receptor affinity of ring and side-chain homologues of etoxadrol and dexoxadrol are described. For the regioselective synthesis of etoxadrol homologues, the regioisomeric 4-azidobutanediols (±)-9 and (±)-14 were employed. A synthesis of the enantiomerically pure azidobutanediols (S)-, (R)-9 and (S)-, (R)-14 was developed and the homochiral building blocks were used for the synthesis of enantiomerically pure etoxadrol and dexoxadrol homologues. The affinity of the racemic and enantiomerically pure primary amines toward the phencyclidine binding site of the NMDA receptor was investigated in receptor binding studies with tritium labeled [3H]-(+)-MK-801 as radioligand. Benzaldehyde derivatives (±)-12a, (±)-13a, and (±)-16a bearing a proton at the acetalic position do not interact significantly with the NMDA receptor. An enantioselective NMDA receptor binding was observed for the trans-configured 2-(2-ethyl-2-phenyl-1,3-dioxolan-4-yl)ethanamine 13b, the (2-ethyl-2-phenyl-1,3-dioxan-4-yl)methanamine 16b, and the (2,2-diphenyl-1,3-dioxan-4-yl)methanamine 16c. The NMDA receptor affinity of these compounds resides almost exclusively in the (S)-configured enantiomers (2S,4S)-13b, (2S,4S)-16b, and (4S)-16c. The lowest Ki-value in this series was found for the (2S,4S)-configured 1,3-dioxolane (2S,4S)-13b (Ki = 69 nM), which is in the range of the Ki-value of the lead compounds etoxadrol and dexoxadrol, indicating that the 2-aminoethyl and the piperidin-2-yl substituents lead to similar NMDA receptor interactions. 相似文献
5.
E. Roman Galan Derek J. Hodgson Yoshinobu Yokomori Ernest L. Eliel M. Bueno Martinez
Juan A. Serrano Blazquez
《Carbohydrate research》1988,180(2):263-276Uncatalyzed reaction between cyclopentadiene and (E)-3,4,5,6,7-pentaacetoxy-1-nitrohept-1-enes having the
-manno,
-galacto, and
-gluco configurations at C-3—C-7 led, in each case, to the four stereoisomeric 5-nitro-6-(1,2,3,4,5-penta-O-acetylpentitol-1-yl)bicyclo[2.2.1]hept-2-enes. Face selectivity is discussed in terms of the sugar-chain configuration. The structures assigned the adducts are based on their n.m.r. spectra, and, in the case of the
-manno compounds, on X-ray data. Also described are the 13C-n.m.r. spectra of the starting nitroalkenes. The crystal structures of (5S,6S)1,2,3,4,5-penta-O-acetyl-1-C-(5-exo-nitrobicyclo[2.2.1]hept-2-en-6-endo-yl-
-manno-pentitol (3a) and (5S,6S)1,2,3,4,5-penta-O-acetyl-1-C-(5-endo-nitrobicyclo[2.2.1]hept-2-en-6-exo-yl-
-manno-pentitol (5a) were determined from three-dimensional, X-ray data. Crystals of 3a are monoclinic, space group P21, with two molecules in a cell of dimensions a = 9.054(3), b = 15.580(11), c = 10.138(4) Å, β = 116.27(3)°. The structure was refined to an R-factor of 0.050 on the basis of 1485 observations. Crystals of 5a are triclinic, space group P1, with one molecule in a cell of dimensions a = 8.680(4), b = 9.760(4), c = 8.695(7) Å, = 98.69(5), β = 103.13(5), γ = 112.09(3)°. The structure was refined to an R-factor of 0.074 based on 970 observations. 相似文献
6.
A. de Raadt S. Feichtenhofer H. Griengl M. F. Klingler H. Weber 《Journal of Molecular Catalysis .B, Enzymatic》2001,11(4-6):361-366
Microbial hydroxylation of 2-(cyclopent-1-enyl)benzoxazole (1) and 2-(cyclohex-1-enyl)benzoxazole (2) by Cunninghamella blakesleeana DSM 1906 and Bacillus megaterium DSM 32, respectively, gave chiral allylic alcohols 3-(benz-1,3-oxazol-2-yl)cyclopent-2-en-1-ol (3) and 3-(benz-1,3-oxazol-2-yl)cyclohex-2-en-1-ol (4) along with achiral ketones 3-(benz-1,3-oxazol-2-yl)cyclopent-2-en-1-one (5) and 3-(benz-1,3-oxazol-2-yl)cyclohex-2-en-1-one (6). Both allylic alcohols were produced in enantiomeric excesses higher than 99%. The determination of their absolute configurations (S in both cases) is described. 相似文献
7.
N. Kositzyna M. Antipin K. Lyssenko P. S. Pregosin G. Trabesinger 《Inorganica chimica acta》1996,250(1-2):365-373
A series of cationic allyl complexes of Pd(II) derived from the diterpene carvone
have been synthesised and characterised using the chelating ligands, bipyridine, 1,8-phenanthroline, neocuproin, S,S (-)-Chiraphos and R (+)-Binap as co-ligands. These complexes can be readily converted to new organic products in which one C---H bond of the allyl methyl has been substituted. The structure of a bipyridyl complex as its tetraphenyl borate salt has been determined via X-ray diffraction. 2-D NOESY studies on the Chiraphos and Binap complexes are reported. The Binap, but not the Chiraphos, complex reveals η3-η3η3 isomerisation at ambient temperature. 相似文献
8.
Hua DH Zhao H Battina SK Lou K Jimenez AL Desper J Perchellet EM Perchellet JP Chiang PK 《Bioorganic & medicinal chemistry》2008,16(9):5232-5246
Total syntheses of (±)-ovalicin, its C4(S*)-isomer 44, and C5-side chain intermediate 46 were accomplished via an intramolecular Heck reaction of (Z)-3-(tert-butyldimethylsilyloxy)-1-iodo-1,6-heptadiene and a catalytic amount of palladium acetate. Subsequent epoxidation, dihydroxylation, methylation, and oxidation led to (3S*,5R*,6R*)-5-methoxy-6-(tert-butyldimethylsilyloxy)-1-oxaspiro[2.5]octan-4-one (2), a reported intermediate. The addition of a side chain with cis-1-lithio-1,5-dimethyl-1,4-hexadiene (27) followed by oxidation afforded (±)-ovalicin. The functional group manipulation afforded a number of regio- and stereoisomers, which allow the synthesis of analogs for bioevaluation. The structure of 44 was firmly established via a single-crystal X-ray analysis. The stereochemistry at C4 generated from the addition reactions of alkenyllithium with ketones 2, 40, and 45 is dictated by C6-alkoxy functionality. Anti-trypanosomal activities of various ovalicin analogs and synthetic intermediates were evaluated, and C5-side chain analog, 46, shows the strongest activity. Compound 44 shows antiproliferative effect against HL-60 tumor cells in vitro. Compounds 46 and a precursor, (3S*,4R*,5R*,6R*)-5-methoxy-4-[(E)-(1′,5′-dimethylhexa-1′,4′-dienyl)]-6-(tert-butyldimethylsilyloxy)-1-oxaspiro[2.5]octan-4-ol (28), may be explored for the development of anti-parasitic drugs. 相似文献
9.
Kinetic results are reported for intramolecular PPh3 substitution reactions of Mo(CO)2(η1-L)(PPh3)2(SO2) to form Mo(CO)2(η2-L)(PPh3)(SO2) (L = DMPE = (Me)2PC2H4P(Me)2 and dppe=Ph2PC2H4PPh2) in THF solvent, and for intermolecular SO2 substitutions in Mo(CO)3(η2-L)(η2-SO2) (L = 2,2′-bipyridine, dppe) with phosphorus ligands in CH2Cl2 solvent. Activation parameters for intramolecular PPh3 substitution reactions: ΔH≠ values are 12.3 kcal/mol for dmpe and 16.7 kcal/mol for dppe; ΔS≠ values are −30.3 cal/mol K for dmpe and −16.4 cal/mol K for dppe. These results are consistent with an intramolecular associative mechanism. Substitutions of SO2 in MO(CO)3(η2-L)(η2-SO2) complexes proceed by both dissociative and associative mechanisms. The facile associative pathways for the reactions are discussed in terms of the ability of SO2 to accept a pair of electrons from the metal, with its bonding transformations of η2-SO2 to η1-pyramidal SO2, maintaining a stable 18-e count for the complex in its reaction transition state. The structure of Mo(CO)2(dmpe)(PPh3)(SO2) was determined crystallographically: P21/c, A=9.311(1), B = 16.344(2), C = 18.830(2) Å, ß=91.04(1)°, V=2865.1(7) Å3, Z=4, R(F)=3.49%. 相似文献
10.
Two new resorcinol derivatives, 4-hydroxy-2-methoxy-6-[(8Z)-pentadec-8-en-1-yl]phenyl acetate (1) and 4-hydroxy-2-methoxy-6-pentadecylphenyl acetate (2), together with known compounds ardisiphenol D (3), 5-tridecylresorcinol (4), 5-pentadecylresorcinol (5), 5-[(8Z)-pentadec-8-en-1-yl]resorcinol (6), belamcandaquinones C and D (7 and 8, resp.), ardisicrenoside A, ardisiacrispin B, (22E)-24-ethyl-5α-cholesta-7,22-dien-3-one, and (22E)-24-ethyl-5α-cholesta-7,22-dien-3β-ol were isolated from the MeOH extract of the roots of Ardisia brevicaulis Diels. Their structures were determined by spectroscopic analysis including ESI- and EI-MS, and NMR data. Cytotoxicities of 1-4 against cell lines A549, MCF-7, and PANC-1 were tested in vitro by the MTT (=3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) method. Compounds 1-4 showed cytotoxic activity against all cell lines stronger than that of cisplatin against A549. 相似文献
11.
Previously, we have shown that substitution of Pro2 for cis-2-aminocyclopentanecarboxylic acid, ACPC in endomorphin-2 results in an analogue with greatly augmented proteolytic stability, high μ-opioid receptor affinity and selectivity. We now report the synthesis and biochemical characterization of [3H][(1S,2R)ACPC2]endomorphin-2 with a specific activity of 1.41 TBq/mmol (38.17 Ci/mmol). Specific binding of [3H][(1S,2R)ACPC2]endomorphin-2 was saturable and of high affinity with an equilibrium dissociation constant, Kd = 1.80 ± 0.21 nM and receptor density, Bmax = 345 ± 27 fmol × mg protein−1 at 25 °C in rat brain membranes. Similar affinity values were obtained in kinetic and displacement assays. Both Na+ and Gpp(NH)p decreased the affinity proving the agonist character of the radioligand. [3H][(1S,2R)ACPC2]endomorphin-2 retained the μ-specificity of the parent peptide. The new radioligand will be a useful tool to map the topographical requirements of μ-opioid peptide binding due to its high affinity, selectivity and enzymatic stability. 相似文献
12.
Jin-Ming Gao Min Wang La-Ping Liu Ge-Hong Wei An-Ling Zhang Cristina Draghici Yasuo Konishi 《Phytomedicine》2007,14(12):821-824
Four ergosterol derivatives (1–4) have been isolated for the first time from the fruiting bodies of a basidiomycete fungus, Lactarius hatsudake, through activity-guided fractionation. Their structures were determined, using spectroscopic analysis, as: (22E,24R)-ergosta-5,7,22-dien-3β-ol (ergosterol, 1); 5,8-epidioxy-(22E,24R)-ergosta-6,22-dien-3β-ol (ergosterol peroxide, 2); 5,8-epidioxy-(24S)-ergosta-6-en-3β-ol (3); and (22E,24R)-ergosta-7,22-dien-3β,5,6β-triol (cerevisterol, 4). Compounds 2 and 3 showed selective inhibitory activity against Crotalus adamenteus venom phospholipase A2 (PLA2) enzyme, but not against Apis mellifcra bee venom PLA2. The antiphospholipase A2 activity of compounds 2 and 3 are reported here for the first time. 相似文献
13.
Georges M. Pavlov Evguenija V. Korneeva Natalia P. Yevlampieva 《International journal of biological macromolecules》1994,16(6):318-323
The hydrodynamic characteristics of the polysaccharide pullulan (polymaltotriose) in water have been investigated and its molecular characteristics have been determined. Experimental values varied over the following ranges: velocity sedimentation coefficient (S): 0.9 < S < 11.2, translational diffusion coefficient (107 cm2 s−1): 1.1 < D < 14.7 and intrinsic viscosity (cm3 g−1): 6.7 < [η] < 164, which corresponds to a change in molecular weight (× 103) in the range 3.9 < MSD < 644. On the basis of analysis of the literature and our experimental data, excluded volume effects have been shown to have a prevailing influence on the chain length of these polysaccharides. The equilibrium rigidity and hydrodynamic chain diameter of pullulan were evaluated on the basis of the theory of hydrodynamic properties of a wormlike necklace, taking into account excluded volume effects. At low M (< 30 × 103) the translation friction data (in contrast to viscometric data) cannot be described in the framework of the theory of linear molecules. 相似文献
14.
Reactions of Cr(CO)3(η6-BT), in which the Cr is π-coordinated to the benzene ring of benzo[b]thiophene (BT), with Cp′(CO)2Re(THF), where Cp′ = η5-C5H5 or η5-C5Me5, give the products Cp′(CO)2Re(η2:η6-μ2-BT)Cr(CO)3 in which the Cr remains coordinated to the benzene ring and Re is bound to the C(2)=C(3) double bond. An X-ray diffraction study of Cp(CO)2Re(η2:η6-μ2-BT)Cr(CO)3 (3) provides details of the geometry. This structure contrasts with that of the Cp′(CO)2Re(BT) complexes that exist as mixtures of isomers in which the BT is coordinated to the Re through either the double bond (2,3-η2) or the sulfur (η1(S)). Thus, the electron-withdrawing Cr(CO)3 group in 3 stabilizes the 2,3-η2 mode of BT coordination to the Cp′(CO)2Re fragment. Implications of these results for catalytic hydrodesulfurization of BT are discussed. Crystal data for 3: triclinic, space group . 相似文献
15.
The methanothermal reactions of M(CO)6 (M = Mo, W) with Na2S2 gave a series of homonuclear clusters [{M(CO)4}n(MS4)]2− (M=Mo, W; N=1, 2), i.e. (Ph4P)2[(CO)4Mo(MoS4)] (I), (Ph4P)2[(CO)4W(WS4)] (II), (Ph4P)2[(CO)4Mo(MoS4)Mo(CO)4] (III) and (Ph4P)2[(CO)4W(WS4)W(CO)4] (IV). The two dimers, I and II, as well as the two trimers, III and IV, are isostructural to each other, respectively. All compounds crystallize in the triclinic space group
with Z=2. The cell dimensions are: a=12.393(8), b=19.303(9), c=11.909(6) Å, =102.39(5), β=111.54(5), γ=73.61(5)°, V=2522(3) Å3 at T=23 °C for I; a=12.390(3), b=19.314(4), c=11.866(2) Å, =102.66(2), β=111.49(1), γ=73.40(2)°, V=2511(1) Å3 at T=23 °C for II; a=11.416(3), b=22.524(4), c=10.815(4) Å, =91.03(2), β=100.57(3), γ=88.96(2)°, V=2733(1) Å3 at T=−100 °C for III, a=11.498(1), b=22.600(4), c=10.864(3) Å, =90.92(2), β=100.85(1), γ=88.58(1)°, V=2771(2) Å3 at T=23 °C for IV. The dimers are each formed by the coordination of the tetrathiometalate as a bidentate chelating ligand to an M(CO)4 fragment while addition of another M(CO)4 fragment to the dimers results in the trimers. All compounds contain both tetrahedral and octahedral metal centers with the formal 6+ and 0 oxidation states, respectively. 相似文献
16.
Toshiaki Yonemura Kimi Shibuya Ken-ichi Okamoto Tomoharu Ama Hiroshi Kawaguchi Takaji Yasui 《Inorganica chimica acta》1997,260(2):m1127-128
Cobalt(III) complexes with a thiolate or thioether ligand, t-[Co(mp)(tren)]+ (2), t-[Co(mtp)(tren)]2+ (1Me) and t-[Co(mta)(tren)]2+ (2Me), (mp = 3-mercaptopropionate, MA = 3-(methylthio)propionate and MTA = 2-(methylthio)acetate) have been prepared in aqueous solutions. The crystal structures of 1, 2, 1Me and 2Me were determined by X-ray diffraction methods. The crystal data are as follows, t-[Co(mp)(tren)]ClO4 (1CIO4): monoclinic, P21/n, A = 10.877(8), B = 11.570(4), c = 12.173(7) Å, β = 92.20(5)°, V = 1531(1) Å3, Z = 4 and R = 0.060; t-[Co(ma)(tren)]Cl·3H2O (2Cl·3H2O): monoclinic, P21/n, a = 7.7688(8), B = 27.128(2), C = 7.858(1) Å, β = 100.63(1)°, V = 1627.7(3) Å3, Z = 4 and R = 0.066; (+)465CD-t-[Co(mtp)(tren)](ClO4)2 ((+)465CD-1Me(ClO4)2): orthorhombic, P212121, A = 10.6610(7), B = 11.746(1), C = 15.555(1) Å, V = 1947.9(3) Å3, Z = 4 and R = 0.068; (+)465CD-t-[Co(mta)(tren)](ClO4)2 ((+)465CD-2Me(ClO4)2): orthorhombic, P212121, a = 10.564(1), B = 11.375(1), C = 15.434(2) Å, V = 1854.7(4) Å3, Z = 4 and R = 0.047. All central Co(III) atoms have approximately octahedral geometry, coordinated by four N, one O, and one S atoms. All of the complexes are only isomer, of which the sulfur atom in the didentate-O,S ligands are located at the trans position to the tertiary amine nitrogen atom of tren. 1 and 1Me contain six-membered chelate ring, and 2 and 2Me do five-membered chelate ring in the didentate ligand. The chirality of the asymmetric sulfur donor atom in (+)465CD-1Me is the S configuration and that in (+)465CD-2Me is the R one. The 1H NMR, 13C NMR and electronic absorption spectral behaviors and electrochemical properties of the present complexes are discussed in relation to their stereochemistries. 相似文献
17.
The ligand 1,4,7-triazacyclononane-1,4,7-tris[2′(R)-2′-propionate](-3)((R)-tacntp3−), binds stereospecifically to transition metal ions. The structures of the complexes [Cr((R)-tacntp)]·NaBr and [Fe((R)-tacntp)]·H2O have been determined by X-ray crystallography. Both complexes have the Λ-configuration but the conformation of the chelate rings in Λ-[Cr((R)-tacntp)] is (λ,λ,λ) with a geometry close to octahedral while in Λ-[Fe((R)-tacntp)] it is (δ,δ,δ) and the geometry is closer to that of a trigonal prism. Chiral induction in the electron transfer reactions of Λ-[Co((R)-tacntp)], Λ-[Fe((R)-tacntp)] and Λ-[Mn((R)-tacntp)] with [Co((RR,SS)-chxn)3]2+ has been investigated. All three reactions are outer-sphere and four isomeric [Co((RR,SS)-chxn)3]3+ products are identified in each case. The oxidants Λ-[Fe((R)-tacntp)] and Λ-[Mn((R)-tacntp)] show very similar selectivities, quite different from those of Λ-[Co((R)-tacntp)]. Reasons for this behavior are discussed. 相似文献
18.
19.
The reversible equilibrium conversion under H2 of [RuCl(dppb) (μ-Cl)]2 (1) to generate (η2-H2) (dppb) (μ-Cl)3RuCl(dppb) in CH2Cl2 (dppb = Ph2P(CH2)4PPh2) has been studied at 0–25 °C by UV-Vis and 31P{1H} NMR spectroscopy, and by stoppe kinetics; the equilibrium constant and corresponding thermodynamic parameters, and the forward and reverse rate constants at 25 °C have been determined. A measured ΔH° value of 0 kJ mol−1 allows for an estimation of an exothermicity of 60 kJ mol−1 for binding an η2-H2 at an Ru(II) centre; a ΔS° value of 60 J mol−1 K−1 indicates that in solution 1 contain s coordinated CH2Cl2. The kinetic and thermodynamic data are compared to those obtained from a previously studied hydrogenation of styrene catalyzed by 1. Preliminary findings on related systems containing Ph2P(CH2)3PPh2 and (C6H11)2P(C6H11)2 are also noted. 相似文献
20.
Marie Ishige Mario Motidome Massayoshi Yoshida Otto R. Gottlieb 《Phytochemistry》1991,30(12):4121-4128
Bark, wood and leaves of Ocotea catharinensis contain respectively 10 (average yield 0.7%.), 15 (average yield 0.004%.) and one (yield 0.4%.) neolignans of the bicyclo[3.2.1]octanoid and the hydrobenzofuranoid structural types, including the new rel-(7S,8R,1′R,4′S,5′R,6′R)-Δ8′-4′,6′-dihydroxy-5′-methoxy-3,4-methylenedioxy-3′-oxo-8.1′,7.5′-neolignan, (7S,8S)-Δ1′,3′,5′,8′-5,3′,5′-trimethoxy-3,4-methylenedioxy-8.1′,7.O.6′,4.O.7′-neolignan, (7R,8S,1′R,3′R)-Δ5′,8′-3,4,3′,5′-tetramethoxy-4′-oxo-8.1′,7.O.6′-neolignan and rel-(7R,8S,1′R,2′S)-Δ4′,8′-2′-hydroxy-3,4-dimethoxy-3′-oxo-8.1′,7.O.2′-neolignan. 相似文献