A pair of novel geometrically isomeric triterpenoid saponins named escins IVa and IVb, together with known escins Ia and Ib. were isolated from the seeds of Aesculus chinensis. Their structures were determined on the ...A pair of novel geometrically isomeric triterpenoid saponins named escins IVa and IVb, together with known escins Ia and Ib. were isolated from the seeds of Aesculus chinensis. Their structures were determined on the basis of spectroscopic evidences and comparison.展开更多
Two new triterpenoid saponins were isolated from the seeds of Aesculus chinensis by preparative HPLC. On the basis of chemical evidence and spectral data, their structures were established as 21 beta-tigloyl-28-acetyl...Two new triterpenoid saponins were isolated from the seeds of Aesculus chinensis by preparative HPLC. On the basis of chemical evidence and spectral data, their structures were established as 21 beta-tigloyl-28-acetylprotoaescigenin 3 beta-O-[beta-D-xylopyranosyl (1 --> 2)] [beta-D-glucopyranosyl (1 --> 4)]-beta-D-glucopyranosiduronic acid (isoescin IIa, 1) and 21 beta-tigloyl-28-acetylprotoaescigenin 3 beta-O-[beta-D-xylopyranosyl (1 --> 2)] [beta-D-glucopyranosyl (1 --> 4)]-beta-D-glucopyranosiduronic acid (isoescin IIb, 2), which are a pair of geometrical isomers.展开更多
12-Methoxypodocarpane-8,11,13-triene 1, the key intermediate in the synthesis of some important diterpenes, was synthesized in an efficient way, which has the characteristics of short route simple operation and high y...12-Methoxypodocarpane-8,11,13-triene 1, the key intermediate in the synthesis of some important diterpenes, was synthesized in an efficient way, which has the characteristics of short route simple operation and high yield.展开更多
To investigate the structural form of gossypol and gossypolone Schiff＇s bases, seven relevant Schiff＇s bases were synthesized and the electrospray ionization-tandem mass spectrometry （ESI-MS/MS） with low-energy co...To investigate the structural form of gossypol and gossypolone Schiff＇s bases, seven relevant Schiff＇s bases were synthesized and the electrospray ionization-tandem mass spectrometry （ESI-MS/MS） with low-energy collision-induced dissociation was used to analyze their fragmentations. A common fragmentation pathway with the loss of RNH2 from those schiff＇s bases quasi-molecular ions was observed and proposed on the basis of their MS/MS spectra data. This common pathway indicated that those Schiff＇s bases existed mainly as the enamine form not the imine form previously showed in most reports.展开更多
A series of analogs of endomorphin-2 （EM-2） with phenylglycine （Phg） in position 3 or 4 were synthesized. In electrospray ionization Fourier transform ion cyclotron resonance （ESI-Fr-ICR） MS/MS spectra of these ...A series of analogs of endomorphin-2 （EM-2） with phenylglycine （Phg） in position 3 or 4 were synthesized. In electrospray ionization Fourier transform ion cyclotron resonance （ESI-Fr-ICR） MS/MS spectra of these compounds, some b, y, a, and internal ions were observed and slight mass differences between the calculated and observed results are obtained. Their sequences were derived successfully. However, the MS/MS patterns of these analogs with Dphg and Lphg were very similar. It is hard to distinguish them by MS/MS spectra. Moreover, if the third position was substituted by phenylglycine （L or D）, a rearrangement could occur in MS/MS experiment to lose proline residue.展开更多
1、2－O－Isopropylidene－3－C－cyano－5－O－benzoyl－α－D－xylose 2 was preparedstereoselectively from 1，2－O－isopropylidene－3－oxo－5－O－benzoyl－α－D－xylose 1．The structure of 2was studied by two－dimensiona...1、2－O－Isopropylidene－3－C－cyano－5－O－benzoyl－α－D－xylose 2 was preparedstereoselectively from 1，2－O－isopropylidene－3－oxo－5－O－benzoyl－α－D－xylose 1．The structure of 2was studied by two－dimensional NMR spectroscopy in conjunction with X－ray crystallography of itscorresponding 5－phenyl－1，2，4－oxadiazole isocarbonucleoside derivative 3． The absoluteconfigurations of 2 and 3，and conformation of 3 are described herein．展开更多
Two new oligopeptides, Asterin A and B, have been isolated from the roots of Aster tataricus L. f., and their structures were elucidated on the basis of spectroscop- ic, chemical and enzymatic methods.
文摘A pair of novel geometrically isomeric triterpenoid saponins named escins IVa and IVb, together with known escins Ia and Ib. were isolated from the seeds of Aesculus chinensis. Their structures were determined on the basis of spectroscopic evidences and comparison.
文摘Two new triterpenoid saponins were isolated from the seeds of Aesculus chinensis by preparative HPLC. On the basis of chemical evidence and spectral data, their structures were established as 21 beta-tigloyl-28-acetylprotoaescigenin 3 beta-O-[beta-D-xylopyranosyl (1 --> 2)] [beta-D-glucopyranosyl (1 --> 4)]-beta-D-glucopyranosiduronic acid (isoescin IIa, 1) and 21 beta-tigloyl-28-acetylprotoaescigenin 3 beta-O-[beta-D-xylopyranosyl (1 --> 2)] [beta-D-glucopyranosyl (1 --> 4)]-beta-D-glucopyranosiduronic acid (isoescin IIb, 2), which are a pair of geometrical isomers.
基金the National Natural Science Foundation of China.
文摘12-Methoxypodocarpane-8,11,13-triene 1, the key intermediate in the synthesis of some important diterpenes, was synthesized in an efficient way, which has the characteristics of short route simple operation and high yield.
基金the National Natural Science Foundation of China.
文摘vinyl-8,11,13-podocatriene 8, which is a model of Carnosic acid type diterpenes, has been synthesized by an expeditious convergent synthetic approach.
文摘To investigate the structural form of gossypol and gossypolone Schiff＇s bases, seven relevant Schiff＇s bases were synthesized and the electrospray ionization-tandem mass spectrometry （ESI-MS/MS） with low-energy collision-induced dissociation was used to analyze their fragmentations. A common fragmentation pathway with the loss of RNH2 from those schiff＇s bases quasi-molecular ions was observed and proposed on the basis of their MS/MS spectra data. This common pathway indicated that those Schiff＇s bases existed mainly as the enamine form not the imine form previously showed in most reports.
文摘A series of analogs of endomorphin-2 （EM-2） with phenylglycine （Phg） in position 3 or 4 were synthesized. In electrospray ionization Fourier transform ion cyclotron resonance （ESI-Fr-ICR） MS/MS spectra of these compounds, some b, y, a, and internal ions were observed and slight mass differences between the calculated and observed results are obtained. Their sequences were derived successfully. However, the MS/MS patterns of these analogs with Dphg and Lphg were very similar. It is hard to distinguish them by MS/MS spectra. Moreover, if the third position was substituted by phenylglycine （L or D）, a rearrangement could occur in MS/MS experiment to lose proline residue.
文摘1、2－O－Isopropylidene－3－C－cyano－5－O－benzoyl－α－D－xylose 2 was preparedstereoselectively from 1，2－O－isopropylidene－3－oxo－5－O－benzoyl－α－D－xylose 1．The structure of 2was studied by two－dimensional NMR spectroscopy in conjunction with X－ray crystallography of itscorresponding 5－phenyl－1，2，4－oxadiazole isocarbonucleoside derivative 3． The absoluteconfigurations of 2 and 3，and conformation of 3 are described herein．
基金This work was supported by the National Science Foundation.
文摘Two new oligopeptides, Asterin A and B, have been isolated from the roots of Aster tataricus L. f., and their structures were elucidated on the basis of spectroscop- ic, chemical and enzymatic methods.
