(3R)-Claussequinone (7-hydroxy-4'-methoxyisoflavanquinone) is the principal constituent of Cyclolobium clausseni Benth. and C. vecchii A. Samp. extracts. C. clausseni contains additionally (3R) mucroquinone (7-hydroxy-8,4'-dimethoxyisoflavanquinone), (3R)-vestitol (7,2'-dihydroxy-4'-methoxyisoflavan), (3R)-α,α-dimethylallylcyclolobin [5'-(1,l -dimethylallyl)-7,3',4'-trihydroxy-2'-methoxyisoflavan], biscyclolobin, 3'-hydroxyformononetin and isoliquiritigenin. The structural proposals for vestitol and claussequinone were confirmed by synthesis.