1,2-Dithiane-4-carboxylic Acid.

4′-Hydroxy­biphenyl-4-carboxylic acid

The title compound, C(13)H(10)O(3), has potential oxygen donor and acceptor sites. Inter-molecular hydrogen bonding between neighboring carboxyl-ate groups leads to the formation of hydrogen-bonded dimers [graph-set motif R(2) (2)(8)]. A second hydrogen-bonding inter-action between the hydr-oxy groups generates a chain and extends the structure into a lamellar layer. One of the benzene rings is...

5-Methyl­isoxazole-4-carboxylic acid

In the title compound, C(5)H(5)NO(3), the mol-ecule lies on a crystallographic mirror plane with one half-mol-ecule in the asymmetric unit. An intramolecular C-H⋯O inter-action is present. In the crystal, strong inter-molecular O-H⋯N hydrogen bonds result in the formation of a linear chain structure along [100], and there are also weak C-H⋯O hydrogen bonds between the chains which help to stabi...

2-(4-Nitro­phen­yl)-1,3-dithiane

The nitro group in the title compound, C(10)H(11)NO(2)S(2), is almost coplanar with the benzene ring, making a dihedral angle of 3.42 (8)°. The 1,3-dithiane ring adopts a chair conformation. The crystal structure is stabilized by inter-molecular C-H⋯O and C-H⋯π [C⋯Cg = 3.4972 (10) Å] inter-actions.

6-Fluoro-4-oxochroman-2-carboxylic acid

The title compound, C(10)H(7)FO(4), is an inter-mediate in the synthesis of the drug Fidarestat, (2S,4S)-2-aminoformyl-6-fluoro-spiro[chroman-4,4'-imidazolidine]-2',5'-dione. The di-hydro-pyran-one ring adopts an envelope conformation with the asymmetric C atom in the flap position. In the crystal, the mol-ecules are linked into zigzag chains along [100] by O-H⋯O hydrogen bonds and C-H⋯π inter-...

On the oxidation of D-1, 3-thiazane-4-carboxylic acid (D-tetrahydro-1,3-thiazine-4-carboxylic acid).