Wu-Lan Zeng

5-(4-Hy­droxy­benzyl­idene)-2,2-dimethyl-1,3-dioxane-4,6-dione

The title compound, C13H12O5, was prepared by the reaction of 2,2-dimethyl-1,3-dioxane-4,6-dione and 4-hydroxybenzaldehyde in ethanol. The 1,3-dioxane ring is in a distorted boat conformation. In the crystal, inversion dimers linked by pairs of O—H⋯O hydrogen bonds generate R 2 2(20) rings.

3-(4-Bromo­benzyl­idene)-1,5-dioxaspiro­[5.5]undecane-2,4-dione

The title molecule, C16H15BrO4, was prepared by the reaction of (R)-2,4-dioxo-1,5-dioxaspiro[5.5]undecane and 4-bromobenzaldehyde with ethanol. The 1,3-dioxane ring exhibits a distorted boat and the fused cyclohexane ring exhibits a chair conformation.

2,2-Dimethyl-5-(2,3,4-trimeth-oxy-benzyl-idene)-1,3-dioxane-4,6-dione.

The title compound, C16H18O7, was prepared by the reaction of 2,2-dimethyl-1,3-dioxane-4,6-dione and 2,3,4-trimethoxybenzaldehyde. The 1,3-dioxane ring is in a slightly distorted boat conformation. The crystal structure is stabilized by weak intermolecular C—H⋯O hydrogen bonds.

5-(3,4-Dimethyl-benzyl-idene)-2,2-dimethyl-1,3-dioxane-4,6-dione.

The title compound, C15H16O4, was prepared by the reaction of 2,2-dimethyl-1,3-dioxane-4,6-dione and 3,4-dimethylbenzaldehyde in ethanol. The 1,3-dioxane ring exhibits an envelope conformation. In the crystal, molecules are linked by weak intermolecular C—H⋯O hydrogen bonds, forming chains parallel to the b axis.

2,2-Dimethyl-5-[(5-methyl-furan-2-yl)methyl-idene]-1,3-dioxane-4,6-dione.

The asymmetric unit of the title compound, C12H12O5, contains two independent molecules. In each, the 1,3-dioxane ring adopts an envelope conformation with the dimethyl-substituted C atom forming the flap. The crystal structure is stabilized by weak intermolecular C—H⋯O hydrogen bonds.

3-(4-Fluoro­benzyl­idene)-1,5-dioxa­spiro­[5.5]undecane-2,4-dione

In the title molecule, C16H15FO4, the fused 1,3-dioxane and cyclohexane rings exhibit a bath and a chair conformation, respectively. In the crystal, weak intermolecular C—H⋯O hydrogen bonds link the molecules into centrosymmetric dimers.

2-Hydroxy-benzoic acid-purin-6-amine (3/1).

In the title 3:1 adduct, 3C7H6O3·C5H5N5, an intramolecular O—H⋯O hydrogen bond occurs in each of the three 2-hydroxybenzoic acid molecules. In the crystal, the components are linked by N—H⋯O and O—H⋯N hydrogen bonds.

2-(1H-Benzotriazol-1-yl)-1-(4-ethyl-benzo-yl)ethyl 2-chloro-benzoate.

In the crystal structure of the title compound, C24H20ClN3O3, weak intermolecular C—H⋯O hydrogen bonds link the molecules into chains extended along the a axis. The crystal studied was found to be an inversion twin.

5,5′-[(2,4-Dichloro­phen­yl)methyl­ene]bis­(2,2-dimethyl-1,3-dioxane-4,6-dione)

The title compound, C19H18Cl2O8, was prepared by the reaction of 2,2-dimethyl-1,3-dioxane-4,6-dione and 2,4-dichlorobenzaldehyde in ethanol. The two 1,3-dioxane rings exhibit boat conformations. In the crystal, molecules are linked by weak intermolecular C—H⋯O and C—H⋯Cl hydrogen bonds, forming chains parallel to the a axis.

3-(2,4-Dichloro-benzyl-idene)-1,5-dioxa-spiro-[5.5]undecane-2,4-dione.

In the title molecule, C16H14Cl2O4, the 1,3-dioxane and cyclohexane rings exhibit distorted boat and chair conformations, respectively. In the crystal, a pair of weak intermolecular C—H⋯O hydrogen bonds link the molecules into an inversion dimer.