Weak C—H⋯X (X = O N) hydrogen bonds in the crystal structure of di­hydro­berberine

摘要

Di­hydro­berberine (systematic name: 9,10-dimeth­oxy-6,8-dihydro-5H-1,3-dioxolo[4,5-g]iso­quinolino­[3,2-a]iso­quinoline), C20H19NO4, a reduced form of pharmacologically important berberine, crystallizes from ethanol without inter­stitial solvent. The mol­ecule shows a dihedral angle of 27.94 (5)° between the two arene rings at the ends of the mol­ecule, owing to the partial saturation of the inner quinolizine ring system. Although lacking classical O—H or N—H donors, the packing in the crystalline state is clearly governed by C—H⋯N and C—H⋯O hydrogen bonds involving the two acetal-type C—H bonds of the 1,3-dioxole ring. Each di­hydro­berberine mol­ecule is engaged in four hydrogen bonds with neighbouring mol­ecules, twice as donor and twice as acceptor, thus forming a two-dimensional sheet network that lies parallel to the (100) plane.