A new alkaloid named stemospironine (I) was isolated together with stemofoline (II) as the main insecticidal constituents of leaves and stems of Stemona japonica Miq. The absolute stereostructure of I has been determined by X-ray crystallographic analysis. Stemofoline (II) showed a much stronger activity than I against silkworm larvae (Bombyx mori L.) by oral administration.

Crystals of dimethylgl_yoxime (C4H8N202) are triclinic, space group P1 with a = 6.075 (3), b = 6.314(3), c = 4.484 (2) A, a = 122.50(3), fl = 91.66 (4), y = 77.75 (3) ° with one molecule per cell. The structure has been redetermined from 521 X-ray intensities measured with Cu Ka radiation (sin 0/2 < 0.60 /k-l). After a conventional least-squares refinement (R = 0.034), population parameters were introduced for octapole deformations of spherical HartreeFock C, N and O atoms in order to fit apparent residual bonding charge density. The agreement improved significantly (R = 0.025). Charge deformations in the oxime group were found to be trigonal for N and tetrahedral for O.