Novel Galloylhamameloses from Hamamelis virginiana1.
关键词
抽象
The range of natural galloylhamameloses is extended by the recognition of the highly unstable novel analogues, the 1- O-(4-hydroxybenzoyl)-2',5-di- O-galloyl-alpha- D-hamamelofuranose and its 1- O-beta-anomer. The observed facile elimination of the C-1 acyl moiety is discussed and a mechanism proposed. These compounds are accompanied in the bark of HAMAMELIS VIRGINIANA by the "conventional" hamamelitannin, the related new 1,2',5-tri- O-galloyl-alpha- D-hamamelofuranose, and a tentatively characterized di- O-galloyl- D-hamamelopyranose, the first pyranose analogue, shown to be also present in commercially available hamamelitannin. The structures of these compounds were established from spectroscopic evidence of their acetate derivatives.