Structural and conformational studies on euphohelioscopins A and B and related diterpenes

Two new toxic diterpenes (euphohelioscopins A and B) and two euphoscopin-type ones (euphoscopins C and D) have been isolated from the plant Euphorbia helioscopia L., and their stereostructures and conformations also been elucidated on the basis of their spectral data and some chemical evidence, together with successful application of molecular mechanics calculations to such flexible molecules as described herein.