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

The title compound, C(16)H(18)O(7), was prepared by the reaction of 2,2-dimethyl-1,3-dioxane-4,6-dione and 2,3,4-trimeth-oxy-benzaldehyde. The 1,3-dioxane ring is in a slightly distorted boat conformation. The crystal structure is stabilized by weak inter-molecular C-H⋯O hydrogen bonds.

5,5'-[(2,4-Dichloro-phen-yl)methyl-ene]bis-(2,2-dimethyl-1,3-dioxane-4,6-dione).

The title compound, C(19)H(18)Cl(2)O(8), was prepared by the reaction of 2,2-dimethyl-1,3-dioxane-4,6-dione and 2,4-dichloro-benzaldehyde in ethanol. The two 1,3-dioxane rings exhibit boat conformations. In the crystal, mol-ecules are linked by weak inter-molecular 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 mol-ecule, C(16)H(14)Cl(2)O(4), the 1,3-dioxane and cyclo-hexane rings exhibit distorted boat and chair conformations, respectively. In the crystal, a pair of weak inter-molecular C-H⋯O hydrogen bonds link the mol-ecules into an inversion dimer.

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

The title compound, C(15)H(16)O(4), was prepared by the reaction of 2,2-dimethyl-1,3-dioxane-4,6-dione and 3,4-dimethyl-benzaldehyde in ethanol. The 1,3-dioxane ring exhibits an envelope conformation. In the crystal, mol-ecules are linked by weak inter-molecular 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, C(12)H(12)O(5), contains two independent mol-ecules. 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 inter-molecular C-H⋯O hydrogen bonds.

3-(4-Bromo-benzyl-idene)-1,5-dioxaspiro-[5.5]undecane-2,4-dione.

The title mol-ecule, C(16)H(15)BrO(4), was prepared by the reaction of (R)-2,4-dioxo-1,5-dioxaspiro-[5.5]undecane and 4-bromo-benzaldehyde with ethanol. The 1,3-dioxane ring exhibits a distorted boat and the fused cyclo-hexane ring exhibits a chair conformation.

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

In the title mol-ecule, C(16)H(15)FO(4), the fused 1,3-dioxane and cyclo-hexane rings exhibit a bath and a chair conformation, respectively. In the crystal, weak inter-molecular C-H⋯O hydrogen bonds link the mol-ecules into centrosymmetric dimers.

Synthesis, characterization, crystal structure and DFT studies on 3-(1H-benzo[d][1,2,3]triazol-1-yl)-1-oxo-1-m-tolylpropan-2-yl-nicotinate.

3-(1H-Benzo[d][1,2,3]triazol-1-yl)-1-oxo-1-m-tolylpropan-2-yl-nicotinate (BOTN) has been synthesized and characterized by elemental analysis, IR, UV-vis and fluorescence spectroscopy. Its crystal structure has also been determined by X-ray single crystal diffraction. For BOTN, density functional theory (DFT) calculations of the structure and vibrational frequencies have been performed at B3LYP/6-311G** level.

(E)-2,2-Dimethyl-5-(3-phenyl-allyl-idene)-1,3-dioxane-4,6-dione.

The title compound, C(15)H(14)O(4), was prepared by the reaction of 2,2-dimethyl-1,3-dioxane-4,6-dione and (Z)-3-phenyl-acryl-aldehyde in ethanol. The dioxane ring is in a sofa conformation with the C atom bonded to the two methyl groups forming the flap. With the exception of the flap atom and the methyl group C atoms, all other non-H atoms are essentially planar, with an r.

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

In the title mol-ecule, C(17)H(18)O(5), which was prepared by the reaction of (R)-1,5-dioxaspiro-[5.5]undecane-2,4-dione and 4-meth-oxy-benzaldehyde with ethanol, the 1,3-dioxane ring is in a distorted envelope conformation with the spiro C atom forming the flap. The crystal structure is stabilized by weak inter-molecular C-H⋯O hydrogen bonds.

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

The title compound, C(13)H(11)FO(4), was prepared by the reaction of 2,2-dimethyl-1,3-dioxane-4,6-dione and 4-fluoro-benz-alde-hyde in ethanol. The 1,3-dioxane ring adopts an envelope conformation. The crystal structure is stabilized by weak inter-molecular C-H⋯O hydrogen bonds.

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

The title compound, C(13)H(12)O(5), was prepared by the reaction of 2,2-dimethyl-1,3-dioxane-4,6-dione and 4-hy-droxy-benz-alde-hyde 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.

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

In the crystal structure of the title compound, C(23)H(18)FN(3)O(3), inter-molecular C-H⋯N hydrogen bonds link the mol-ecules into chains extended along the c axis. The packing is further stabilized by weak C-H⋯O and C-H⋯F inter-actions. The F atom is disordered over two equally occupied 1- and 5-positions of the benzene ring.

3-[(5-Methyl-furan-2-yl)methyl-ene]-1,5-dioxaspiro-[5.5]undecane-2,4-dione.

There are two crystallographically independent mol-ecules in the asymmetric unit of the title compound, C(15)H(16)O(5). In each, the 1,3-dioxane ring is in an envelope conformation with the C atom common to the cyclo-hexane ring forming the flap. The dihedral angles between the five essentially planar [maximum deviations from the least-squares planes of 0.

2-(1H-Benzotriazol-1-yl)-1-(3-methyl-benzo-yl)ethyl benzoate.

In the title mol-ecule, C(23)H(19)N(3)O(3), the dihedral angles between the mean plane of the benzotriazole ring system and the benzene and phenyl rings are 9.67 (9) and 86.08 (10)°, respectively.

3-(2-Furylmethyl-ene)-1,5-dioxaspiro-[5.5]undecane-2,4-dione.

In the title mol-ecule, C(14)H(14)O(5), the 1,3-dioxane ring is in an envelope conformation with the ring C atom common to the cyclo-hexane ring forming the flap. The other five atoms of the 1,3-dioxane ring are essentially planar [maximum deviation from the least-squares plane = 0.041 (3) Å] and form a dihedral angle of 13.

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

In the title 3:1 adduct, 3C(7)H(6)O(3)·C(5)H(5)N(5), an intra-molecular O-H⋯O hydrogen bond occurs in each of the three 2-hydroxy-benzoic acid mol-ecules. In the crystal, the components are linked by N-H⋯O and O-H⋯N hydrogen bonds.

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

The title compound, C(13)H(11)FO(4), was prepared by the reaction of 2,2-dimethyl-1,3-dioxane-4,6-dione and 2-fluoro-benzaldehyde in ethanol. In the crystal structure, mol-ecules are linked into chains by weak inter-molecular C-H⋯O hydrogen bonds.

(Z)-3-(3-Phenyl-allyl-idene)-1,5-dioxa-spiro-[5.5]undecane-2,4-dione.

In the title compound, C(18)H(18)O(4), the 1,3-dioxane ring adopts a distorted envelope conformation with the C atom common to the cyclo-hexane ring forming the flap. In the crystal, inversion dimers linked by pairs of C-H⋯O hydrogen bonds occur.

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

In the crystal structure of the title compound, C(24)H(20)ClN(3)O(3), weak inter-molecular C-H⋯O hydrogen bonds link the mol-ecules into chains extended along the a axis. The crystal studied was found to be an inversion twin.

2-(1H-1,2,3-Benzotriazol-1-yl)-1-(4-ethyl-benzo-yl)ethyl 2,4-dichloro-benzoate.

In the title mol-ecule, C(24)H(19)Cl(2)N(3), the dihedral angles between the benzotriazole group and the ethyl- and dichloro-substituted benzene rings are 16.53 (1) and 82.09 (1)°, respectively.

2-(1H-1,2,3-Benzotriazol-1-yl)-1-m-toluoylethyl 2,4-dichloro-benzoate.

In the title compound, C(23)H(17)Cl(2)N(3)O(3), the dihedral angles between the mean planes of the benzotriazole system and the methyl- and dichloro-substituted benzene rings are 47.72 (1) and 13.06 (1)°, respectively.