CONDENSED TANNINS - CIRCULAR-DICHROISM METHOD OF ASSESSING ABSOLUTE-CONFIGURATION AT C-4 OF 4-ARYLFLAVAN-3-OLS, AND STEREOCHEMISTRY OF THEIR FORMATION FROM FLAVAN-3,4-DIOLS
CONDENSED TANNINS - CIRCULAR-DICHROISM METHOD OF ASSESSING ABSOLUTE-CONFIGURATION AT C-4 OF 4-ARYLFLAVAN-3-OLS, AND STEREOCHEMISTRY OF THEIR FORMATION FROM FLAVAN-3,4-DIOLS
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DOI：
10.1039/c39780000698
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发表时间：
1978-01-01
影响因子：
--
通讯作者：
ROUX, DG
中科院分区：
文献类型：
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作者：
BOTHA, JJ;FERREIRA, D;ROUX, DG
已知绝对构型的黄烷-3，4-二醇与间苯三酚和间苯二酚在C-4位的立体选择性缩合反应在室温下进行，2，3-反式异构体的构型部分或完全保留，2，3-顺式异构体的构型发生转化，这些现象被认为在缩合单宁的形成中具有重要意义;由C-4处的芳基发色团贡献的多重Cotton效应主导c.d. [圆二色性]光谱的结果4-芳基-2，3-反式-和2，3-顺式-黄烷-3-醇，使明确确定其绝对构型在这个手性中心。
Stereoselective condensation at C-4 of flavan-3,4-diols of known absolute configuration with phloroglucinol and resorcinol proceeds at ambient temperatures with partial or complete retention of configuration for 2,3-trans-isomers and with inversion for 2,3-cis-isomers, phenomena that are considered to be of prime significance in condensed tannin formation; multiple Cotton effects contributed by aryl chromophores at C-4 dominate the c.d. [circular dichroism] spectra of the resultant 4-aryl-2,3-trans- and 2,3-cis-flavan-3-ols, enabling unambiguous determination of their absolute configurations at this chiral center.