5-(Pyridin-4-ylmeth­yl)-1H-pyrazolo­[3,4-d]pyrimidin-4(5H)-one

In the title compound, C11H9N5O, the pyrazolo­pyrimidin-4-one ring system is almost planar, with a maximum deviation of 0.0546 (13) Å for the O atom. The crystal packing is stabilized by inter­molecular N—H⋯N, C—H⋯O and C—H⋯N hydrogen bonds. In addition, π–π stacking is found between the pyridine ring and the pyrazolo­pyrimidin-4-one ring systems, with centroid–centroid distances in the range 3.9627 (12)–4.6781 (12) Å

1,3-Bis[2-hy­droxy-2-(6-meth­oxy-2,2-dimethyl-3a,5,6,6a-tetra­hydro-2H-furo[2,3-d][1,3]dioxol-5-yl)eth­yl]-2,3-dihydro-1H-1,3-benzodiazol-2-one

In the title benzimidazolone, C27H38N2O11, which has N-bound glycosidic units, all five-membered O-heterocyclic rings adopt envelope conformations [for the outer rings, the C atom with the dimethyl groups represents the flap atom]. The two glycosidic units are related by a non-crystallographic twofold rotation axis that passes through the carbonyl portion. In the mol­ecular structure, the hy­droxy groups are hydrogen-bond donors to the carbonyl O atom. Weak inter­molecular C—H⋯O hydrogen bonding is present in the crystal structure

3-{2-[(3-{(E)-2-[4-(Dimethyl­amino)­phen­yl]ethen­yl}quinoxalin-2-yl)­oxy]eth­yl}-1,3-oxazolidin-2-one monohydrate

In the title compound, C23H24N4O3·H2O, the 1,3-oxazoline ring is nearly planar [maximum deviation = 0.059 (2) Å] and its mean plane is twisted by 30.12 (8)° with respect to the quinoxaline fused-ring system; the benzene ring is nearly coplanar with the quinoxaline fused-ring system [dihedral angle = 2.52 (2)°]. The water mol­ecule of crystallization is hydrogen-bond donor to an N atom of the quinoxaline ring system as well as an O atom of the oxazolinone unit, the two hydrogen bonds generating a chain running along the c axis

3-Methyl-1-propargylquinoxalin-2(1H)-one

The ten-membered fused ring of the title compound, C12H10N2O, is essentially planar in the two independent mol­ecules of the asymmetric unit (r.m.s. deviations = 0.012 and 0.015 Å)