TANNINS AND RELATED-COMPOUNDS .39. PROCYANIDIN C-GLUCOSIDES AND AN ACYLATED FLAVAN-3-OL GLUCOSIDE FROM THE BARKS OF CINNAMOMUM-CASSIA BLUME AND CINNAMOMUM-OBTUSIFOLIUM NEES

Along with procyanidins B-1 (4), B-2 (5), B-5 (6) and B-7 (7), and the doubly linked proanthocyanidin, A-2 (8), two new procyanidin glucosides have been isolated from the bark of Cinnamomum cassia Blume (Lauraceace), and characterized as procyanidin B-2 8-C- and 6-C-.beta.-D-glucopyranosides (1 and 2, respectively) on the basis of proton and carbon-13 nuclear magnetic resonance examinations and the results of thiolytic degradation. In addition, from the bark of Cinnamomum obtusifolium Nees, an acylated flavan-3-ol glucoside (3) has been isolated, together with the known proanthocyanidins B-1 (4), B-2 (5), B-5 (6) and A-2 (8). The structure of 3 has been established to be (+)-catechin-5-O-.beta.-D-(2"-O-feruloyl-6"-O-p-coumaroyl)-glucopyranoside on the basis of chemical and spectral evidence.