1-(1-Hy-droxy-eth-yl)-7,8-dihydro-indolo[2,3-a]pyridine-[3,4-g] quinolizin-5(13H)-one (angustoline) monohydrate from Nauclea subdita (Rubiaceae)

Abstract

The title compound (trivial name: angustoline monohydrate), C 20H 17N 3O2·H 2O, features a fused-ring system formed by one five- and four six-membered rings. The nearly planar benzimidazole portion (r.m.s. deviation = 0.008 Å) and the nearly planar 2,7-naphthyridin-1-one portion (r.m.s. deviation = 0.022 Å) of the fused-ring system are slightly twisted, with a dihedral angle of 9.47 (8)°, owing to the tetra-hedral nature of the two methyl-ene linkages in the central six-membered ring. The secondary N atom acts as a hydrogen-bond donor to the water molecule of crystallization. In the crystal, the amino and hy-droxy groups, and the water mol-ecule are engaged in hydrogen bonding, generating a three-dimensional network. © Liew et al. 2011.