排序方式: 共有8条查询结果,搜索用时 15 毫秒
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应用1H-1H COSY,NOESY,13C-1H COSY等2DNMR和DEPT技术,完成了赤霉酸甲酯(2),13-O-乙酰基赤霉素甲酯(3)及其3位差向异构体(4)的1H和13CNMR化学位移的全指定,并探讨了它们的相对构型,相关质子间的偶合常数也支持所得结果。 相似文献
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Xiaojing Liu Ruijiao Chen Feixia Duan Junhao Jia Yuqin Zhou Xiaochuan Chen 《Tetrahedron letters》2017,58(42):3947-3950
The first synthesis of (+)-botryolide-E and its C-7 epimer has been achieved in 8 steps from d-Glucono-δ-lactone, and their antibiotic activities were also investigated preliminarily. 相似文献
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应用NMR技术,其中包括:1H NMR、13C NMR、DEPT、COSY、13C-1H COSY和HMBC,对联萘酚磷酰胺的一对差向异构体的结构进行了研究.对S-R及R-R差向异构体的所有碳氢信号进行了一一归属,并依此考查了差向异构体的构象,分析结果得到了X-ray单晶衍射结果的证实. 相似文献
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In comparison with the NMR data of salvinorin A and its 8-epimer, the published structure of deacetyl-1,10-didehydrosalvinorin G was revised to its 8-epimer. The stereochemistry of 8-epi-deacetyl-1,10-didehydrosalvinorin G was further confirmed by NOESY and chemical synthesis. 相似文献
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Study of electrospray ionization tandem mass spectrometry of the benzofuranone compounds 总被引:1,自引:0,他引:1
Zhan Qi Niu~ 《中国化学快报》2008,19(3):324-328
A detailed analysis of benzofuranone compounds under multiple tandem mass spectrometry (ESI-MS^n) conditions is reported. Element composition data of the fragment ions were obtained with the aid of comparison of the multiple tandem mass spectra of four compounds, and the structures of which are identical except for some substituted groups or epimers or cis-trans-isomers. Attempts have been made to provide rational pathways for the formation of the fragment ions from these protonated compounds. And the structure-fragmentation relationships will facilitate the characterization of the structures of other analogs. 相似文献
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A highly stereocontrolled asymmetric total synthesis of epimer of (+)-7-deoxypancratistatin has been achieved from readily available starting materials via unified strategy employing Sharpless asymmetric dihydroxylation, ring closing metathesis, Overman rearrangement, hydrogenolysis and Bischler–Napieralski reaction in 15 purification steps with 15% overall yield. 相似文献
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Jaru Taechalertpaisarn 《Tetrahedron letters》2010,51(44):5822-5826
A new pyrrolidinyl peptide nucleic acid (PNA) comprising of an alternate sequence of 4′-nucleobase-modified proline with (2′R,4′S) configuration and a (1S,2S)-2-aminocyclopentanecarboxylic acid [(2′R,4′S)-acpcPNA] backbone was synthesized and its DNA-, RNA- and self-pairing properties studied. Tm and CD studies suggested that the (2′R,4′S)-acpcPNA forms antiparallel hybrids to DNA and RNA with high sequence and direction specificity. The stability of these hybrids is comparable to those of the (2′R,4′R)-acpcPNA hybrids previously reported by our group. On the other hand, experiments with a self-complementary sequence indicated that the new (2′R,4′S)-acpcPNA forms a more stable antiparallel self-hybrid than (2′R,4′R)-acpcPNA. 相似文献
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Benedetto Natalini Roccaldo Sardella Antimo Gioiello Giovanni Carbone Malgorzata Dawgul Roberto Pellicciari 《Journal of separation science》2009,32(12):2022-2033
Owing to the re-flourished interest towards the bile acids (BAs) as versatile signalling hormones endowed with diverse endocrine functions, the development of reliable analytical protocols monitoring the synthesis of new BA-based receptor modulators, still represents a cogent concern. On this basis, for the first time, a HPLC study has been engaged with the aim to set up suitable chromatographic conditions for the analysis of three different epimeric couples of 23-methyl-substituted unconjugated BAs. Three different methods (one for each couple) have been successfully established and then validated. Good precision and accuracy (evaluated both in the short and long period) as well as appreciably low LOD and LOQ values have turned out. Moreover, the engagement of an evaporative light scattering detector (ELSD) has proven its high effectiveness for the analysis of such steroidal species. 相似文献
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