Absolute configuration of 3β-acet-oxy-olean-11,12-aziridin-28,13-β-olide.

The title compound, C(32)H(49)NO(4), has been isolated from the dichloro-methane extract of the stem bark of Garcinia atroviridis Griff. ex T. Anders. Rings A and B, B and C, and C and D are trans-fused, whereas rings D and E are cis-fused. Rings A, B, C and E have slightly distorted chair conformations, while ring D is most heavily distorted towards a half-chair conformation owing to the strain induced by the lactonization. The ester group attached to ring A is in an equatorial position.