The absolute stereostructures of three rare D:B-friedobaccharane skeleton triterpenes from the leaves of Salacia chinensis

Three new rare D:B-friedobaccharane skeleton triterpenes named foliasalacins D1 (1), D2 (2), and D3 (3) together with the 20 known ones (4–23) were isolated from the leaves of Salacia chinensis Linn., collected in Thailand. The absolute stereostructures of the D:B-friedobaccharane-type compounds (1–3) were characterized on the basis of chemical and physiochemical evidences.