大叶冬青叶中2个新的三萜皂苷(4)
Acid hydrolysis of 1 afforded Dglucose， Larabinose and Lrhamnose according to the HPLC analysis of their derivatives. In combination of the large 3JH1H2 coupling constants (5.6 Hz for Larabinose and 7.6 Hz for Dglucose)， the relative configuration of the anomeric centers of Larabinose and Dglucose were deduced as α and β， respectively. The αconfiguration for the Lrhamnose could be established by comparison of the NMR data with those reported [14]. The linkage and sequence of the sugar units were determined by the HMBC correlations between H1 (δH 5.12) of glucose
and C3 (δC 82.5) of arabinose ......
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and C3 (δC 82.5) of arabinose ......
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