Correlation between the absolute configuration and the CD spectra of organic peroxides was studied by ab initio method with a mo- d el moleeule CH_3-O-O-CH_3.For P form when 0°≤θ(twist angle of C-O-O-C) <90&...Correlation between the absolute configuration and the CD spectra of organic peroxides was studied by ab initio method with a mo- d el moleeule CH_3-O-O-CH_3.For P form when 0°≤θ(twist angle of C-O-O-C) <90°, there is positive Cotton effect;when 90°<θ≤180°, there is nega- tive Cotton effect;the curve is bisignate at θ=90°.展开更多
To investigate the anti-ulcer effect of bisabolangelone reduction derivatives, the sesquiterpene was further proceeded with dihydroxylation reaction. The structure of the target compound was characterized by IR, ESI-M...To investigate the anti-ulcer effect of bisabolangelone reduction derivatives, the sesquiterpene was further proceeded with dihydroxylation reaction. The structure of the target compound was characterized by IR, ESI-MS, 2D NMR and elemental analysis, and its absolute configuration was confirmed with a Flack parameter of 0.08（16） by X-ray crystallography using a Cu radiation source. Compound（3）, C（15）H（26）O5, crystal data： monoclinic system, space group P21, a = 11.467（2）, b = 6.0303（12）, c = 11.711（2） A, β = 99.70（3）°, V = 798.3（3） A3, Z = 2, F（000） = 312, Dc = 1.191 g/cm3, μ = 0.723 mm-1） R = 0.0303 and wR = 0.0797 for 2590 independent reflections（Rint = 0.0164） and 2563 observed ones（I 〉 2σ（I））.展开更多
The absolute configuration of rohitukine, isolated from the stem-bark of Dysoxylum binectariferum, was determined to be 5,7-dihydroxy-2-methyl-8-[4-(3S, 4R-3-hydroxy-1-methyl) -piperidinyl]-4H-1-benzopyran-4-one by X-...The absolute configuration of rohitukine, isolated from the stem-bark of Dysoxylum binectariferum, was determined to be 5,7-dihydroxy-2-methyl-8-[4-(3S, 4R-3-hydroxy-1-methyl) -piperidinyl]-4H-1-benzopyran-4-one by X-ray crystallographic analysis on the crystal of 4-bromobenzoyl derivatives of rohitukine. At the same time, the modified Mosher method was proved to be unsuitable for determining the absolute configuration of C-3 position in rohitukine.展开更多
A new alkylpyrrole derivative,fusariumin A(1),was isolated from the culture broth of the fungus Fusarium sp.The absolute configuration of fuasiumin A has been established as(2'R,3'R)using a combination of RDC(...A new alkylpyrrole derivative,fusariumin A(1),was isolated from the culture broth of the fungus Fusarium sp.The absolute configuration of fuasiumin A has been established as(2'R,3'R)using a combination of RDC(residual dipolar coupling)-based NMR and DFT-supported chiroptical spectroscopy.It is worth to note that in this study without the aid of the RDC analysis,an unambiguous determination of configuration and conformation was not feasible due to the excessive conformational possibilities of this open-chain compound.展开更多
Racemic O-methyl O-pheayl thiophosphoric acid 1 has been successfully resolved through its quinine and brucine salts in methanol solution by fractional crystallization. The absolute configurations of the optically act...Racemic O-methyl O-pheayl thiophosphoric acid 1 has been successfully resolved through its quinine and brucine salts in methanol solution by fractional crystallization. The absolute configurations of the optically active 1 have been established as (+)-R-1 and (-)-S-1 by chemical correlation.展开更多
The title compound (+)-(a-hydroxybenzyl)phenylphosphinic acid (C13H13O3P, Mr = 248.20) has been synthesized and characterized by 31P NMR, 1H NMR and elemental analysis. X-ray diffraction analysis at 293(2) K indicates...The title compound (+)-(a-hydroxybenzyl)phenylphosphinic acid (C13H13O3P, Mr = 248.20) has been synthesized and characterized by 31P NMR, 1H NMR and elemental analysis. X-ray diffraction analysis at 293(2) K indicates that the compound belongs to monoclinic system, space group C2 with cell parameters: a = 23.560(8), b = 6.947(2), c = 7.854(3) ? b = 91.273(6)? V = 1285.2(7) 3, Z = 4, Dc = 1.283 g/cm3, F(000) = 520 and m(MoKa) = 0.207 mm-1. The number of independent reflections amounts to 1991, of which 1507 are observed reflections. The crystal structure has been determined by direct methods (SHELXL-97). The structure parameters are refined by full-matrix least-squares on F2 to R = 0.0437 and wR = 0.0893. The flack x parameter is 0.0001. The absolute configuration of the a-carbon in the title compound is S.展开更多
The title compound, (+)-O-phenyl cyclophosphorodiamidate (C28H33N2O2P, Mr = 460.53), has been synthesized and characterized by 31P NMR, 1H NMR and elemental analysis. X-ray diffraction analysis at 273(2) K indicates t...The title compound, (+)-O-phenyl cyclophosphorodiamidate (C28H33N2O2P, Mr = 460.53), has been synthesized and characterized by 31P NMR, 1H NMR and elemental analysis. X-ray diffraction analysis at 273(2) K indicates that it belongs to orthorhombic system, space group P212121 with a = 11.518(4), b = 13.449(4), c = 16.539(5) ? V = 2562(1) 3, Z = 4, Dc = 1.194 g/cm3, F(000) = 984 and m(MoKa) = 0.134 mm-1. The structure parameters were refined by full-matrix least-squares on F2 to R = 0.0459 and wR = 0.0640. The flack x parameter is 0.03(10), and the absolute configuration of the phosphorus atom in the title compound is S.展开更多
Crystal structure of the levocloperastine fendizoate （C80H76Cl2N2O10, C20H25ClNO＋· C20H13O4-） has been determined by single-crystal X-ray diffraction. The crystal is of triclinic system, space group P1 with a ...Crystal structure of the levocloperastine fendizoate （C80H76Cl2N2O10, C20H25ClNO＋· C20H13O4-） has been determined by single-crystal X-ray diffraction. The crystal is of triclinic system, space group P1 with a = 10.1059（18）, b = 11.957（2）, c = 15.383（3） , α = 104.666（2）, β = 90.9700（10）, γ = 110.744（2）°, Z = 1, V = 1670.0（5） 3, Dc = 1.289 g/cm3, F（000） = 684, μ（MoKα） = 0.161 mm-1, Mr = 1296.33, the final R = 0.0343 and wR = 0.0676. The cations and anions are linked by the COO…NH hydrogen bonds of 2.709（3） and 2.690（3） and COO…OH hydrogen bonds of 2.632（3） and 2.631（3） . The configuration of the only one chiral carbon atom in this compound is R（rectus）.展开更多
Three pairs of glycosidic 8,4′-oxyneolignane diastereoisomers, named isatioxyneolignosides A-F(1–6), were isolated from an aqueous extract of Isatis indigotica roots. Their structures and absolute configurations wer...Three pairs of glycosidic 8,4′-oxyneolignane diastereoisomers, named isatioxyneolignosides A-F(1–6), were isolated from an aqueous extract of Isatis indigotica roots. Their structures and absolute configurations were elucidated by comprehensive spectroscopic data analysis and enzyme hydrolysis. The validity of Δδ_(C8-C7) values to distinguish threo and erythro aryl glycerol units and Cotton effects at 235±5 nm to determine absolute configurations at C-8 in 1–6 and their aglycones(1a–6a) are discussed.展开更多
Podophyllotoxone(1) was isolated from the roots of Dysosma versipellis. The structure was determined by spectroscopic analysis in combination with single-crystal X-ray analysis. The absolute configuration of compound ...Podophyllotoxone(1) was isolated from the roots of Dysosma versipellis. The structure was determined by spectroscopic analysis in combination with single-crystal X-ray analysis. The absolute configuration of compound 1 was assigned based on the Flack parameter. It showed significant inhibitory activities against human prostate cancer cells PC3 and DU145 with IC50 values being 14.7 and 20.6 μmol·L-1, respectively. It also arrested the cells at G2/M phase. Tubulin polymerization assay showed that it inhibited the tubulin polymerization in a dose-dependent manner, and molecular docking analysis revealed a different binding mode with tubulin as compared with those known tubulin inhibitors.展开更多
Buagafuran is a novel drug candidate derived from natural product.Its absolute configuration has been confirmed by electronic circular dichroism combined with modern quantum-chemical calculation using time-dependent d...Buagafuran is a novel drug candidate derived from natural product.Its absolute configuration has been confirmed by electronic circular dichroism combined with modern quantum-chemical calculation using time-dependent density functional theory.The predicted UV absorbance peak is underestimated by several nanometers compared with the experimental data.The applicability of empirical rule for the C=C-C-O system in Buagafuran has also been discussed.Our results show that electronic circular dichroism could be a useful tool for the absolute configuration assignment of chiral drugs,especially for the oily or semisolid substances,whose crystal structures are impossible to obtain.展开更多
A stereo-selective palladium-catalyzed one-pot Tsuji-Trost reaction was used to prepare fourβ-thiogalactosides from unsaturated D-galactal and thiol.Their structures were characterized by nuclear magnetic resonance s...A stereo-selective palladium-catalyzed one-pot Tsuji-Trost reaction was used to prepare fourβ-thiogalactosides from unsaturated D-galactal and thiol.Their structures were characterized by nuclear magnetic resonance spectra and high-resolution electrospray ionization mass spectra.The absolute configuration was confirmed with a Flack parameter of 0.019(15)by X-ray crystallography using a Cu radiation source.Compound 6 a(C_(21)H_(24)O_(4)S):orthorhombic system,space group P2_(1)2_(1)2_(1),a=9.0919(4),b=9.6313(4),c=22.5936(11)A,V=1978.45(15)A^(3),Z=4,F(000)=792,D_(c)=1.250 g/cm^(3),μ=1.636 mm^(-1),R=0.0478 and wR=0.1384 for 3621 independent reflections(Rint=0.0390)and 3326 observed ones(I>2σ(I)).3-(4,5)-Dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide(MTT)cell viability assays indicated that these thiogalactosides showed anti-proliferative activities against human gastric cancer HGC-27 cells with IC_(50)values of 69~88μM.展开更多
Lewis acid-catalyzed[1,3]-sigmatropic O→C rearrangement was used to synthesize C-glycosides derivatives.The structure of the target compound was characterized by NMR and HR-ESI-MS,and its absolute configuration was c...Lewis acid-catalyzed[1,3]-sigmatropic O→C rearrangement was used to synthesize C-glycosides derivatives.The structure of the target compound was characterized by NMR and HR-ESI-MS,and its absolute configuration was confirmed.Compound 8(C(29)H(29)ClN4O7):monoclinic system,space group P212121,a=6.1484(2),b=12.3625(3),c=37.0127(8)A,V=2813.32(13)A3,Z=4,F(000)=1216.0,Dc=1.372 g/cm^3,μ=1.662 mm^1,R=0.0522 and wR=0.1358 for 5611 independent reflections(R(int)=0.0778)and 5169 observed ones(I>2σ(I)).展开更多
Monosaccharides are one of the most important structural components of biomolecules, such as polysac- charides, nucleic acids, glycolipids and glycoproteins. In structural analysis of polysaccharides and gly- coconjug...Monosaccharides are one of the most important structural components of biomolecules, such as polysac- charides, nucleic acids, glycolipids and glycoproteins. In structural analysis of polysaccharides and gly- coconjugates, the absolute configurations （D or L） of the constituent monosaccharides are usually deter- mined by measurement of the optical rotation, CD spectra or characteristic chromatographic retention behavior. However, each method has its unique advantages and limitations which should be considered while using them. In this review, an overview of the different methods for the determination of absolute configuration of monosaccharides and their underlying principles are summarized to serve as a reference for researchers.展开更多
Since two asymmetric centres are usually present in the bisbenzylisoquinolines,the circular dichroism is known to be an important method to elucidate their stereochemistry.We studied the relationships of the CD spectr...Since two asymmetric centres are usually present in the bisbenzylisoquinolines,the circular dichroism is known to be an important method to elucidate their stereochemistry.We studied the relationships of the CD spectra with the stereochemistry of synthetic RR-(1),SS-(2),RS-daurisoline(3) and SR-daurisoline(4).By comparision of the CD spectrum of natural daurisoline(1)from Menis- permum dauricum(Menispermaceae)with those of synthetic enantiomers,the absolute configuration was established as RR-daurisoline(1).展开更多
Schisanpropinoic acid(1),a new bergamotane sesquiterpenoid,and schisanpropinin(2),a new tetrahydrofuran lignan with a rare epoxyethane unit,were identified from the stems and leaves of Schisandra propinqua var.propinq...Schisanpropinoic acid(1),a new bergamotane sesquiterpenoid,and schisanpropinin(2),a new tetrahydrofuran lignan with a rare epoxyethane unit,were identified from the stems and leaves of Schisandra propinqua var.propinqua.Their structures were determined based on comprehensive spectroscopic and mass spectrometric analysis.The absolute configuration of 1 was determined by X-ray analysis.Compounds 1 and 2 were tested for their cytotoxic activity against five human tumor cell lines.展开更多
Otamixaban is a potent （Ki=0.5 nM） fXa inhibitor currently in late-stage clinical develop-ment at Sanofi for the management of acute coronary syndrome. Being unproductive in obtaining a suitable crystal of Otamixaba...Otamixaban is a potent （Ki=0.5 nM） fXa inhibitor currently in late-stage clinical develop-ment at Sanofi for the management of acute coronary syndrome. Being unproductive in obtaining a suitable crystal of Otamixaban, the required enantiomeric characterization has been accomplished using vibrational circular dichroism （VCD） spectroscopy. Selected by a spectrum similarity index, the calculated spectra of several higher energy conformers were found to match well with the observed spectra. The characteristic IR bands of these conformers were also identified and attributed to the solvation effect. Combined with both the single crystal x-ray diffraction results for an intermediate and the proton NMR study, the absolute configuration of Otamixaban is unambiguously determined to be （R,R）.展开更多
A new isobenzofuran derivative( 1) was isolated from the marine Streptomyces sp. W007 and its structure was determined through extensive spectroscopic analyses, including 1D-NMR, 2D-NMR, and ESI-MS. The absolute confi...A new isobenzofuran derivative( 1) was isolated from the marine Streptomyces sp. W007 and its structure was determined through extensive spectroscopic analyses, including 1D-NMR, 2D-NMR, and ESI-MS. The absolute configuration of compound 1 was determined by a combination of experimental analyses and comparison with reported data, including biogenetic reasoning, J-coupling analysis, NOESY, and 1 H- 1 HCOSY. Compound 1 exhibited no cytotoxicity against human cells of gastric cancer BGC-823, lung cancer A549, and breast cancer MCF7.展开更多
The crystal structure of the title compound N-(1-ethoxycarbonyl-ethyl) 1-ethoxycarbonylmethy-3-ethyl-1,2,3,4-tetrahydro-4-oxo-1,3,2-benzodiazaphosphorin-2-carbox amide 2-oxide, (C19H_26N3O7P, Mr = 439.41), was determi...The crystal structure of the title compound N-(1-ethoxycarbonyl-ethyl) 1-ethoxycarbonylmethy-3-ethyl-1,2,3,4-tetrahydro-4-oxo-1,3,2-benzodiazaphosphorin-2-carbox amide 2-oxide, (C19H_26N3O7P, Mr = 439.41), was determined by single crystal X-ray diffraction at 299(1) K. It crystallizes in the triclinic system, space group P (No.2) with a = 8.955(2), b = 11.863(2), c = 12.309(2) ?, ( = 62.67(3),β= 68.10(3), ( = 78.07(3)(, V = 1077(1) ?3, Z = 2, Dx =1.355 g·cm－3, ( = 0.71073 ?, ( = 0.1657 mm－1 and F(000) = 464. The structure was solved by direct methods. The final R factor is 0.071 and Rw is 0.076 for 2176 observed reflections with I ≥3((I). The results from X-ray crystallography analysis of the isomer with 31P NMR spectra exhibited as ( 4.09 show that the absolute configuration of the chiral phosphorus atom at P(1) was proved to be S-form, with reference to the known configuration of R-alanine moiety.展开更多
文摘Correlation between the absolute configuration and the CD spectra of organic peroxides was studied by ab initio method with a mo- d el moleeule CH_3-O-O-CH_3.For P form when 0°≤θ(twist angle of C-O-O-C) <90°, there is positive Cotton effect;when 90°<θ≤180°, there is nega- tive Cotton effect;the curve is bisignate at θ=90°.
基金supported by the National Natural Science Foundation of China(No.21602123)China Scholarship Council(No.201508420062)Youth Talent Development Foundation of China Three Gorges University
文摘To investigate the anti-ulcer effect of bisabolangelone reduction derivatives, the sesquiterpene was further proceeded with dihydroxylation reaction. The structure of the target compound was characterized by IR, ESI-MS, 2D NMR and elemental analysis, and its absolute configuration was confirmed with a Flack parameter of 0.08（16） by X-ray crystallography using a Cu radiation source. Compound（3）, C（15）H（26）O5, crystal data： monoclinic system, space group P21, a = 11.467（2）, b = 6.0303（12）, c = 11.711（2） A, β = 99.70（3）°, V = 798.3（3） A3, Z = 2, F（000） = 312, Dc = 1.191 g/cm3, μ = 0.723 mm-1） R = 0.0303 and wR = 0.0797 for 2590 independent reflections（Rint = 0.0164） and 2563 observed ones（I 〉 2σ（I））.
文摘The absolute configuration of rohitukine, isolated from the stem-bark of Dysoxylum binectariferum, was determined to be 5,7-dihydroxy-2-methyl-8-[4-(3S, 4R-3-hydroxy-1-methyl) -piperidinyl]-4H-1-benzopyran-4-one by X-ray crystallographic analysis on the crystal of 4-bromobenzoyl derivatives of rohitukine. At the same time, the modified Mosher method was proved to be unsuitable for determining the absolute configuration of C-3 position in rohitukine.
基金Support by the National Natural Science Foundation of China(U1132607)to J.K.L.the DFG(Forschergruppe FOR 934)to C.Gas well as the Chinese/German foundation(GZ1104)to H.S.and C.G.is acknowledged.
文摘A new alkylpyrrole derivative,fusariumin A(1),was isolated from the culture broth of the fungus Fusarium sp.The absolute configuration of fuasiumin A has been established as(2'R,3'R)using a combination of RDC(residual dipolar coupling)-based NMR and DFT-supported chiroptical spectroscopy.It is worth to note that in this study without the aid of the RDC analysis,an unambiguous determination of configuration and conformation was not feasible due to the excessive conformational possibilities of this open-chain compound.
基金This project was supported by National Natural Science Foundation of China
文摘Racemic O-methyl O-pheayl thiophosphoric acid 1 has been successfully resolved through its quinine and brucine salts in methanol solution by fractional crystallization. The absolute configurations of the optically active 1 have been established as (+)-R-1 and (-)-S-1 by chemical correlation.
基金Financial support by the National Natural Science Foundation of China (No.29872016)
文摘The title compound (+)-(a-hydroxybenzyl)phenylphosphinic acid (C13H13O3P, Mr = 248.20) has been synthesized and characterized by 31P NMR, 1H NMR and elemental analysis. X-ray diffraction analysis at 293(2) K indicates that the compound belongs to monoclinic system, space group C2 with cell parameters: a = 23.560(8), b = 6.947(2), c = 7.854(3) ? b = 91.273(6)? V = 1285.2(7) 3, Z = 4, Dc = 1.283 g/cm3, F(000) = 520 and m(MoKa) = 0.207 mm-1. The number of independent reflections amounts to 1991, of which 1507 are observed reflections. The crystal structure has been determined by direct methods (SHELXL-97). The structure parameters are refined by full-matrix least-squares on F2 to R = 0.0437 and wR = 0.0893. The flack x parameter is 0.0001. The absolute configuration of the a-carbon in the title compound is S.
基金Financially supported by the National Natural Science Foundation of China (No.20272025) and Ph.D. Programs Foundation of Ministry of Education of China
文摘The title compound, (+)-O-phenyl cyclophosphorodiamidate (C28H33N2O2P, Mr = 460.53), has been synthesized and characterized by 31P NMR, 1H NMR and elemental analysis. X-ray diffraction analysis at 273(2) K indicates that it belongs to orthorhombic system, space group P212121 with a = 11.518(4), b = 13.449(4), c = 16.539(5) ? V = 2562(1) 3, Z = 4, Dc = 1.194 g/cm3, F(000) = 984 and m(MoKa) = 0.134 mm-1. The structure parameters were refined by full-matrix least-squares on F2 to R = 0.0459 and wR = 0.0640. The flack x parameter is 0.03(10), and the absolute configuration of the phosphorus atom in the title compound is S.
文摘Crystal structure of the levocloperastine fendizoate （C80H76Cl2N2O10, C20H25ClNO＋· C20H13O4-） has been determined by single-crystal X-ray diffraction. The crystal is of triclinic system, space group P1 with a = 10.1059（18）, b = 11.957（2）, c = 15.383（3） , α = 104.666（2）, β = 90.9700（10）, γ = 110.744（2）°, Z = 1, V = 1670.0（5） 3, Dc = 1.289 g/cm3, F（000） = 684, μ（MoKα） = 0.161 mm-1, Mr = 1296.33, the final R = 0.0343 and wR = 0.0676. The cations and anions are linked by the COO…NH hydrogen bonds of 2.709（3） and 2.690（3） and COO…OH hydrogen bonds of 2.632（3） and 2.631（3） . The configuration of the only one chiral carbon atom in this compound is R（rectus）.
基金Financial support from the National Natural Sciences Foundation of China(NNSFCGrant Nos.81373287,81630094,and 30825044)
文摘Three pairs of glycosidic 8,4′-oxyneolignane diastereoisomers, named isatioxyneolignosides A-F(1–6), were isolated from an aqueous extract of Isatis indigotica roots. Their structures and absolute configurations were elucidated by comprehensive spectroscopic data analysis and enzyme hydrolysis. The validity of Δδ_(C8-C7) values to distinguish threo and erythro aryl glycerol units and Cotton effects at 235±5 nm to determine absolute configurations at C-8 in 1–6 and their aglycones(1a–6a) are discussed.
基金supported by the Fund of Guangxi Key Laboratory of Functional Phytochemicals Research and Utilization(Nos.FPRU2013-4,and ZRJJ2013-4)the National Natural Science Foundation of China(No.21072078)+1 种基金the Fundamental Research Funds for the Central Universities(No.11609202)the Guangdong High Level Talent Scheme to R.W.J
文摘Podophyllotoxone(1) was isolated from the roots of Dysosma versipellis. The structure was determined by spectroscopic analysis in combination with single-crystal X-ray analysis. The absolute configuration of compound 1 was assigned based on the Flack parameter. It showed significant inhibitory activities against human prostate cancer cells PC3 and DU145 with IC50 values being 14.7 and 20.6 μmol·L-1, respectively. It also arrested the cells at G2/M phase. Tubulin polymerization assay showed that it inhibited the tubulin polymerization in a dose-dependent manner, and molecular docking analysis revealed a different binding mode with tubulin as compared with those known tubulin inhibitors.
基金supported by the Fundamental Research Funds for the Central Institutes(No.2012ZD03)
文摘Buagafuran is a novel drug candidate derived from natural product.Its absolute configuration has been confirmed by electronic circular dichroism combined with modern quantum-chemical calculation using time-dependent density functional theory.The predicted UV absorbance peak is underestimated by several nanometers compared with the experimental data.The applicability of empirical rule for the C=C-C-O system in Buagafuran has also been discussed.Our results show that electronic circular dichroism could be a useful tool for the absolute configuration assignment of chiral drugs,especially for the oily or semisolid substances,whose crystal structures are impossible to obtain.
基金the National Natural Science Foundation of China(No.82003621)Natural Science Foundation of Hubei Province(2020CFB205)Educational Commission of Hubei Province(Q20201204)。
文摘A stereo-selective palladium-catalyzed one-pot Tsuji-Trost reaction was used to prepare fourβ-thiogalactosides from unsaturated D-galactal and thiol.Their structures were characterized by nuclear magnetic resonance spectra and high-resolution electrospray ionization mass spectra.The absolute configuration was confirmed with a Flack parameter of 0.019(15)by X-ray crystallography using a Cu radiation source.Compound 6 a(C_(21)H_(24)O_(4)S):orthorhombic system,space group P2_(1)2_(1)2_(1),a=9.0919(4),b=9.6313(4),c=22.5936(11)A,V=1978.45(15)A^(3),Z=4,F(000)=792,D_(c)=1.250 g/cm^(3),μ=1.636 mm^(-1),R=0.0478 and wR=0.1384 for 3621 independent reflections(Rint=0.0390)and 3326 observed ones(I>2σ(I)).3-(4,5)-Dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide(MTT)cell viability assays indicated that these thiogalactosides showed anti-proliferative activities against human gastric cancer HGC-27 cells with IC_(50)values of 69~88μM.
基金the National Natural Science Foundation of China(No.21602123)Youth Talent Development Foundation of China Three Gorges University。
文摘Lewis acid-catalyzed[1,3]-sigmatropic O→C rearrangement was used to synthesize C-glycosides derivatives.The structure of the target compound was characterized by NMR and HR-ESI-MS,and its absolute configuration was confirmed.Compound 8(C(29)H(29)ClN4O7):monoclinic system,space group P212121,a=6.1484(2),b=12.3625(3),c=37.0127(8)A,V=2813.32(13)A3,Z=4,F(000)=1216.0,Dc=1.372 g/cm^3,μ=1.662 mm^1,R=0.0522 and wR=0.1358 for 5611 independent reflections(R(int)=0.0778)and 5169 observed ones(I>2σ(I)).
基金supported by State Key Program of National Natural Science Foundation of China (grant number 81430095)
文摘Monosaccharides are one of the most important structural components of biomolecules, such as polysac- charides, nucleic acids, glycolipids and glycoproteins. In structural analysis of polysaccharides and gly- coconjugates, the absolute configurations （D or L） of the constituent monosaccharides are usually deter- mined by measurement of the optical rotation, CD spectra or characteristic chromatographic retention behavior. However, each method has its unique advantages and limitations which should be considered while using them. In this review, an overview of the different methods for the determination of absolute configuration of monosaccharides and their underlying principles are summarized to serve as a reference for researchers.
基金This work was supported by the National Natural Science Foundation of China.
文摘Since two asymmetric centres are usually present in the bisbenzylisoquinolines,the circular dichroism is known to be an important method to elucidate their stereochemistry.We studied the relationships of the CD spectra with the stereochemistry of synthetic RR-(1),SS-(2),RS-daurisoline(3) and SR-daurisoline(4).By comparision of the CD spectrum of natural daurisoline(1)from Menis- permum dauricum(Menispermaceae)with those of synthetic enantiomers,the absolute configuration was established as RR-daurisoline(1).
基金the National Natural Science Foundation of China(81373290 and 21322204).
文摘Schisanpropinoic acid(1),a new bergamotane sesquiterpenoid,and schisanpropinin(2),a new tetrahydrofuran lignan with a rare epoxyethane unit,were identified from the stems and leaves of Schisandra propinqua var.propinqua.Their structures were determined based on comprehensive spectroscopic and mass spectrometric analysis.The absolute configuration of 1 was determined by X-ray analysis.Compounds 1 and 2 were tested for their cytotoxic activity against five human tumor cell lines.
文摘Otamixaban is a potent （Ki=0.5 nM） fXa inhibitor currently in late-stage clinical develop-ment at Sanofi for the management of acute coronary syndrome. Being unproductive in obtaining a suitable crystal of Otamixaban, the required enantiomeric characterization has been accomplished using vibrational circular dichroism （VCD） spectroscopy. Selected by a spectrum similarity index, the calculated spectra of several higher energy conformers were found to match well with the observed spectra. The characteristic IR bands of these conformers were also identified and attributed to the solvation effect. Combined with both the single crystal x-ray diffraction results for an intermediate and the proton NMR study, the absolute configuration of Otamixaban is unambiguously determined to be （R,R）.
基金Supported by the Open Fund of Key Laboratory of Experimental Marine Biology,Chinese Academy of Sciences(No.KF2015No07)the Innovative and Entrepreneurial Training Program of College Students,Tianjin University of Commerce(No.2015052)
文摘A new isobenzofuran derivative( 1) was isolated from the marine Streptomyces sp. W007 and its structure was determined through extensive spectroscopic analyses, including 1D-NMR, 2D-NMR, and ESI-MS. The absolute configuration of compound 1 was determined by a combination of experimental analyses and comparison with reported data, including biogenetic reasoning, J-coupling analysis, NOESY, and 1 H- 1 HCOSY. Compound 1 exhibited no cytotoxicity against human cells of gastric cancer BGC-823, lung cancer A549, and breast cancer MCF7.
基金Foundation for University Key Teacher by the Ministry fo Education
文摘The crystal structure of the title compound N-(1-ethoxycarbonyl-ethyl) 1-ethoxycarbonylmethy-3-ethyl-1,2,3,4-tetrahydro-4-oxo-1,3,2-benzodiazaphosphorin-2-carbox amide 2-oxide, (C19H_26N3O7P, Mr = 439.41), was determined by single crystal X-ray diffraction at 299(1) K. It crystallizes in the triclinic system, space group P (No.2) with a = 8.955(2), b = 11.863(2), c = 12.309(2) ?, ( = 62.67(3),β= 68.10(3), ( = 78.07(3)(, V = 1077(1) ?3, Z = 2, Dx =1.355 g·cm－3, ( = 0.71073 ?, ( = 0.1657 mm－1 and F(000) = 464. The structure was solved by direct methods. The final R factor is 0.071 and Rw is 0.076 for 2176 observed reflections with I ≥3((I). The results from X-ray crystallography analysis of the isomer with 31P NMR spectra exhibited as ( 4.09 show that the absolute configuration of the chiral phosphorus atom at P(1) was proved to be S-form, with reference to the known configuration of R-alanine moiety.
