The alkaloids of Cynoglossum australe R.Br. and C. amabile Stapf & Drummond

Abstract

Two new pyrrolizidine alkaloids, cynaustraline and cynaustine, have been isolated from Cynoglossum australe R,.Br., and echinatine and a third new alkaloid, amabiline, from C. amabile Stapf & Drummond. Cynaustraline, cynaustine, and amabiline are, respectively, (+)- isoretronecanol, (+)-supinidine, and (-)-supinidine esters of viridifloric acid. This is the first isolation of an ester of a (+)- enantiomer of an allylic amino alcohol.