Mustapha Tiouabi

In the title compound, C₁₂H₁₀O₆, an intramolecular O—H...O hydrogen bond forms an S(6) ring motif. The molecule is essentially planar with an r.m.s. deviation of 0.051 Å for all non-H atoms. In the crystal molecules are linked by C—H...O hydrogen bonds and a C—H...π interaction, forming a supramolecular framework.

In the molecule of 6,8-dimethoxy-3-methyl-1H-isochromen-1-one, C₁₂H₁₂O₄, (I), the two methoxy groups are directed anti with respect to each other. In the molecule of the brominated derivative, 5-bromo-6,8-dimethoxy-3-methyl-1H-isochromen-1-one, that crystallized as a chloroform monosolvate, C₁₂H₁₁BrO₄·CHCl₃, (II·CHCl₃ ), the methoxy groups are directed syn to each other. In the crystal of I, molecules are linked by bifurcated C—H...O hydrogen bonds, forming chains along the c-axis direction. The chains are linked by C—H...π interactions, forming a supramolecular framework. In the crystal of II·CHCl₃ , molecules are linked by C—H...O hydrogen bonds forming 2₁ helices parallel to the b-axis direction. The chloroform solvate molecules are linked to the helices by C—H...O(carbonyl) hydrogen bonds. The helices stack up the c-axis direction and are linked by offset π–π interactions [intercentroid distance = 3.517 (3) Å], forming layers parallel to the (100) plane. Compound II·CHCl₃ was refined as a two-component twin. Two chlorine atoms of the chloroform solvate are disordered over two positions and were refined with a fixed occupancy ratio of 0.5:0.5.

In the title compound, C₁₄H₁₈O₈, (I), the methoxycarbonyl [–C(=O)OCH₃] and the acetic acid [–CH₂C(=O)OH] groups are inclined to the benzene ring by 79.24 (11) and 76.71 (13)°, respectively, and are normal to each other with a dihedral angle of 90.00 (13)°. In the crystal, molecules are linked by a pair of O—H...O hydrogen bonds forming the familiar acetic acid inversion dimer. The dimers are linked by two C—H...O hydrogen bonds and an offset π–π interaction [intercentroid distance = 3.6405 (14) Å], forming layers lying parallel to the (10\overline{1}) plane. The layers are linked by a third C—H...O hydrogen bond and a C—H...π interaction to form a supramolecular framework.

In the title compound, C₁₇H₂₇NO₂, the piperidine ring has a chair conformation and is positioned normal to the benzene ring. In the crystal, molecules are linked by C—H...O hydrogen bonds, forming chains propagating along the c-axis direction.