Tetrahydroberberine, a pharmacologically active naturally occurring alkaloid

Tetrahydroberberine (systematic name: 9,10‐dimethoxy‐5,8,13,13a‐tetrahydro‐6H‐benzo[g][1,3]benzodioxolo[5,6‐a]quinolizine), C20H21NO4, a widely distributed naturally occurring alkaloid, has been crystallized as a racemic mixture about an inversion center. A bent conformation of the molecule is observed, with an angle of 24.72 (5)° between the arene rings at the two ends of the reduced quinolizinium core. The intermolecular hydrogen bonds that play an apparent role in crystal packing are 1,3‐benzodioxole –CH2...OCH3 and –OCH3...OCH3 interactions between neighboring molecules.