4-Chloro-7-hydr­oxy-6-methyl-1,7-naphthyridin-8(7H)-one

The title compound, C9H7ClN2O2, was prepared by reaction of methyl 4-chloro-3-(prop-1-yn­yl)picolinate with hydroxy­l­amine in MeOH/KOH solution. The two essentially planar mol­ecules which make up the asymmetric unit have almost identical geometries and and are linked into dimeric aggregates via pairs of O—H⋯O hydrogen bonds. These aggregates have almost perfect inversion symmetry; however, quite unusually, the inversion center of the dimer does not coincide with the crystallographic inversion center

3-Amino-5-bromo-2-iodo­pyridine

The reaction of 3-amino-5-bromo­pyridine with N-iodo­succinimide in the presence of acetic acid produces the title compound, C5H4BrIN, with an iodo substituent in position 2 of the pyridine ring. The crystal structure features rather weak inter­molecular N—H⋯N hydrogen bonds linking the mol­ecules into chains along the z axis of the crystal

6-(2,6-Dimethyl­phen­yl)pyrido[2,3-d]pyrimidin-7-amine

In the title compound, C15H14N4, the pyrido[2,3-d]pyrimidine system is almost ideally planar (r.m.s. deviation 0.028 Å) with its mean plane almost orthogonal to the 2,6-dimethyl­phenyl plane. The dihedral angle formed by these planes [87.3 (2)°] is close to the predicted value (89.7°) obtained by mol­ecular-mechanics force-field calculations. Only one of the two active amine H atoms participates in hydrogen bonding, which links mol­ecules into centrosymmetric dimers