ThePoranthera corymbosa alkaloids. III. Molecular structure and absolute configuration of poranthericine hydrobromide

Crystals of the hydrobromide of poranthericine, C₁₅H₂₇NO, an alkaloid isolated from the plantPoranthera corymbosa Brogn. (family Euphorbiaceae) were found to belong to the orthorhombic space groupP2₁2₁2₁, with unit cell dimensionsa = 12·761,b = 15·144 andc = 8·030 Å, andZ = 4. The structure was solved by the heavy-atom method and refined with 1276 reflections to a residual of 0·091 The molecule was found to consist of three saturated six-membered rings fused on to a common central nitrogen atom, with methyl, ethyl and hydroxyl groups attached to the periphery. All rings had thechair conformation and were fusedtrans to one another. The absolute configuration was determined using the anomalous scattering power of the bromine atom.