Structure cristalline et moléculaire d'un nouvel alcaloïde indolique, l'Akagérine: C20H24N2O2

Akagerine is a new alkaloid first isolated by one of us (LA) from roots of Strychnos usambarensis. The crystal structure was determined by direct methods from three-dimensional diffractometer data. The crystals are tetragonal. The absolute configuration was not determined. This is the first report of a seven-membered ring with an N1-C17 bond (conventional notation for indole alkaloid). The lone-pair of electrons on N4 is cis with respect to C(3)H and C(15)H.The cohesion of the structure is the result of one hydrogen bond OH...N (2.77O Angstroem) and van der Waals interactions.