NOVEL GALLOYLHAMAMELOSES FROM HAMAMELIS-VIRGINIANA

The range of natural galloylhamameloses is extended by the recognition of the highly unstable novel analogues, the enzoyl)-2',5-di-O-galloyl -alpha-D-hamamelofuranose and its 1-O-beta-anomer. The observed facile elimination of the C-l acyl moiety is discussed and a mechanism propo sed. These compounds are accompanied in the bark of Hamamelis virginia na 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 b e also present in commercially available hamamelitannin. The structure s of these compounds were established from spectroscopic evidence of t heir acetate derivatives.