The structure and synthesis of proguibourtinidins from Cassia Abbreviata

Article abstract of DOI:10.1016/0031-9422(95)00656-7

An acetone extract of the bark of Cassia abbreviata yielded guibourtinidol-(4β → 8)-epiafzelechin, guibourtinidol-(4α → 8)-epiafzelechin, guibourtinidol-(4α → 8)-catechin, guibourtinidol-(4β →; 8)-epicatechin and ent-guibourtinidol-(4β → 8)-epicatechin. The structures of the proguibourtinidin dimers were confirmed by synthesis via mild acid-condensation. Guibourtinidol-(4α → 8)-afzelechin, previously isolated from Acacia leuderitzii, was also synthesized. Another two proguibourtinidol oligomers, namely, guibourtinidol-(4α → 8)-afzelechin and guibourtinidol(4α → 6)-afzelechin were products of the previous synthesis but neither of them have been reported to date. Copyright