Enantioselective Total Syntheses of (+)-Gallocatechin, (-)-Epigallocatechin, and 8-C-Ascorbyl-(-)-epigallocatechin
Enantioselective Total Syntheses of (+)-Gallocatechin, (-)-Epigallocatechin, and 8-C-Ascorbyl-(-)-epigallocatechin
复制标题
( )-没食子儿茶素、(-)-表没食子儿茶素和 8-C-抗坏血酸-(-)-表没食子儿茶素的对映选择性全合成
DOI：
10.1002/asia.201201168
复制
发表时间：
2013-04-01
影响因子：
4.1
通讯作者：
Yang, Zhen
中科院分区：
文献类型：
--
作者：
Lin, Guang;Chang, Le;Yang, Zhen
Tea has attracted considerable levels of attention because of its beneficial effects on human health, such as reducing serum cholesterol levels, preventing arteriosclerosis, and lowering the incidence of several human cancers and AIDS.[1] Tea leaves contain a variety of different catechins, including (+)-catechin (C, 1),(À)-epicatechin (EC, 2),(+)-gallocatechin (GC, 3),(À)-epigallocatechin (EGC, 4), and(À)-epigallocatechin-3-gallate(EGCG, 5; Scheme 1).[1c, 2]In 1989, 8-C-ascorbyl-(À)-epigallocatechin-3-gallate (6) and 8-C-ascorbyl-(À)-epigallocatechin (7) were isolated from oolong tea by Nishioka and co-workers.[3] A subsequent biological investigation of the thirty-eight catechins derived from tea by Lee et al.[4] indicated that 6 and 7 demonstrated their inhibitory effects against HIV replication in H9 lymphocyte cells, providing EC50 values of 4 and 10 μg mLÀ1, respectively. In 2005, Nakai et al. also reported the isolation of compounds 6 and 7 from oolong tea and indicated their inhibitory activity against pancreatic lipases in vitro with an IC50 of 0.791 and 0.646 μm, respectively.[5] The structure of 7 was elucidated through a combination of NMR spectroscopy and mass spectrometry [3, 6] and was found to contain a densely oxygenated polyphenol framework with six stereogenic centers, together with a rare and sensitive hemiketal moiety. The interesting molecular structure and intriguing biological activity of compound 7, together with the synthetic challenges associated with its high
