Ammonium hydrogen (RS)-[(5-methyl-2-oxo-1,3-oxazolidin-3-yl)meth­yl]phospho­nate

In the title compound, NH4 +·C5H9NO5P−, the five-membered methyl­oxazolidin-2-one unit is disordered over two positions, the major component having a site occupancy of 0.832 (9). A three-dimensional network of O—H⋯O and N—H⋯O hydrogen bonds stabilizes the crystal structure

Betti bases from 4-(3-pyridazo)-1-naphthol: synthesis, coordination behaviour and unusual substitution reactions

A series of Betti bases from 4‐(3‐pyridyl)azo‐1‐naphthol dye, possessing flexible methylene or more constrained aryl‐methyne spaced NH‐containing side‐chains, were obtained and characterized. It was shown by NMR spectroscopy that the ligands exist in keto form. The products’ structure was confirmed by single crystal XRD of a selected sample. A study on the coordination ability of the ligands with silver(I) was performed, leading to an unexpected substitution reaction

(4-Carbamoylphenyl)boronic acid

In the title compound, C7H8BNO3, the molecule lies on an inversion center leading to a statistical disorder of the B(OH)2 and CONH2 groups. In the crystal structure, molecules are linked by N—H...O and O—H...O hydrogen bonds, forming sheets parallel to the bc plane. The B(OH)2 and CONH2 groups are twisted out of the mean plane of the benzene ring by 23.9 (5) and 24.6 (6)°, respectively

3-Carboxyphenylboronic acid–theophylline (1/1)

The title two-component molecular crystal [systematic name: 3-(dihydroxyboranyl)benzoic acid–1,3-dimethyl-7H-purine-2,6-dione (1/1)], C7H7BO4·C7H8N4O2, comprises theophylline and 3-carboxyphenylboronic acid molecules in a 1:1 molar ratio. In the crystal, molecules are self-assembled by O—H...O and N—H...N hydrogen bonds, generating layers parallel to (-209). The layers are stacked through π–π [centroid–centroid distance = 3.546 (2) Å] and C—H...π interactions

3-[2-(5-tert-Butyl-1,2-oxazol-3-yl)hydrazinylidene]chroman-2,4-dione

In the title compound, C16H15N3O4, the dihedral angle between the chromane and isoxazole rings [r.m.s. deviations = 0.042 and 0.007 Å, respectively] is 20.33 (12)°. The molecular geometry is stabilized by an intramolecular N—H...O hydrogen bond. In the crystal, N—H...O hydrogen bonds generate chains along the c-axis direction. The crystal studied was a non-morohedral twin

Switching azonaphthols containing a side chain with limited flexibility. Part 1. Synthesis and tautomeric properties

A series of azo dyes, possessing amide fragments with restricted flexibility tethered to 4-(phenyldiazenyl)naphthalen-1-ol, was obtained from 1-hydroxy-2-naphthoic acid by subsequent conversion to amides and diazo coupling. It was shown that the position of the tautomeric equilibrium in solution strongly depends on the solvent in both UV and NMR concentration scale. The compounds exist as pure enol forms in chloroform and hydrocarbons, while in polar solvents (acetone, acetonitrile, alcohols) a tautomeric mixture is observed. According to the quantum-chemical calculations the aggregation of the keto tautomer is the possible reason for this shift in the position of the tautomeric equilibrium. To support the theoretical predictions, it was found that from acetone the keto form crystallizes as a dimer with hydrogen bonding between N1–H in the one molecule and amide Cdouble bond; length as m-dashO in the other forming a three-dimensional structure. The importance of the side-chain nitrogen atom on the dimer formation was confirmed by solution and solid state study of 4- (phenyldiazenyl)-2-acetylnaphthalen-1-ol. The results indicate that the new azo-dyes obtained could be suitable candidates for switching and sensing applications in non- polar solvents

Synthesis of 4-acetyl-2(3<i>H</i>)-benzothiazolone: Sulfur bioisostere of benzoxazolone allelochemicals

<p></p> <p>A multi-step methodology for the synthesis of 4-acetyl-2(3<i>H</i>)-benzothiazolone was developed in order to prepare a new biomimetic analogue of benzoxazolone allelochemicals. The compound was prepared from commercially available <i>o</i>-toluidine in 23% overall yield. The structure of 4-acethyl-2(3<i>H</i>)-benzothiazolone was confirmed by NMR spectroscopy and X-ray crystallography.</p