1-Chloro-4-propoxythio­xanthone

In the title compound (systematic name: 1-chloro-4-propoxy-10-thia­anthracen-9-one), C₁₆H₁₃ClO₂S, the asymmetric unit contains two parallel molecules. In both molecules, the three rings in the thio­xanthone moiety are coplanar, the deviations being within the range ±0.086 (3) Å.

10-(5-Chloro-2-hydroxy­benzyl­idene)anthrone acetonitrile solvate

The title compound, C₂₁H₁₃ClO₂·CH₃CN, was prepared from anthrone and 5-chloro-2-hydroxy­benzaldehyde and recrystallized from acetonitrile. The central six-membered ring has an asymmetric boat conformation, in which the carbon­yl C atom and the opposite C atom deviate from the plane of the other four atoms by 0.170 (5) and 0.302 (5) Å, respectively.

3,6-Di­propyl-N,N'-di-o-tolyl-1,2,4,5-tetrazine-1,4-dicarbox­amide

The title compound, C₂₄H₃₀N₆O₂, crystallizes with two mol­ecules in the asymmetric unit, both lying on twofold rotation axes. In both mol­ecules, the central tetrazine ring adopts a boat conformation.

Ethyl 3,6-di­phenyl-1,4-di­hydro-1,2,4,5-tetrazine-1-carboxylate

The title compound, C₁₇H₁₆N₄O₂, was prepared from ethyl chloro­formate and 3,6-di­phenyl­di­hydro-1,2,4,5-tetrazine. The central six-membered ring has an asymmetric boat conformation.

Prop-2-ynyl 3-(3,4-di­hydroxy­phenyl)­prop-2-enoate monohydrate

Crystals of the title compound, C₁₂H₁₀O₄·H₂O, were obtained from the Knoevenagel condensation reaction of 3,4-di­hydroxy­benz­aldehyde and monoprop-2-ynyl malonate. The almost planar mol­ecule is the E isomer. There are intermolecular O—H...O and C—H...O hydrogen bonds and π–π interactions, which contribute to the formation of the crystal structure.

Diprop­yl 3,6-bis­(4-chloro­phen­yl)-1,2-dihydro-1,2,4,5-tetra­zine-1,2-dicarboxyl­ate

The title compound, C₂₂H₂₂Cl₂N₄O₄, was prepared from prop­yl chloro­formate and 3,6-bis­(4-chloro­phen­yl)-1,2-dihydro-1,2,4,5-tetra­zine. The six-membered 1,2-dihydro-1,2,4,5-tetra­zine ring has a twist conformation.

Prop­yl 3,6-diphen­yl-1,4-dihydro-1,2,4,5-tetra­zine-1-carboxyl­ate

The title compound, C₁₈H₁₈N₄O₂, was prepared from prop­yl chloro­formate and 3,6-diphen­yl-1,2-dihydro-1,2,4,5-tetra­zine. The central six-membered ring has a boat conformation. In the crystal structure, mol­ecules are linked via N—H...N [N...N = 3.015 (4) Å] and C—H...O [C...O = 3.265 (6) Å] hydrogen bonds to form extended chains along [100].

2-Meth­yl-2-nitro­prop­yl methane­sulfonate

The title compound, C₅H₁₁NO₅S, has been obtained by reacting 2-meth­yl-2-nitro­propanol with methane­sulfon­yl chloride. The average S=O and S—O bond lengths are 1.414 (3) and 1.570 (3) Å, respectively. The mol­ecules are linked via C—H...O inter­actions, forming a three-dimensional network.

17a-Methyl-4-androstene-3b,17b-diol monohydrate

In the title compound, C₂₀H₃₂O₂·H₂O, ring A is a slightly distorted half-chair, rings B and C have regular chair conformations, and ring D approximates to an envelope form. Mol­ecules are connected via O—H...O hydrogen bonds, generating a three-dimensional network.

3,6-Bis(p-chloro­phen­yl)-1,4-bis­(p-tolyl­sulfon­yl)-1,4-dihydro-1,2,4,5-tetra­zine

The title compound, C₂₈H₂₂Cl₂N₄O₄S₂, was prepared from triethyl­amine and N-(α,4-dichloro­benzyl­idene­amino)-p-toluene­sulfonamide and proved to be a 1,4-dihydro-s-tetra­zine derivative. In the mol­ecule, which possesses a crystallographically imposed inversion centre, the tetra­zine ring is essentially planar.

10-(3-Acetamido­benzyl­idene)anthrone

The title compound, C₂₃H₁₇NO₂, was prepared by reacting 10-(3-amino­benzyl­idene)anthrone and acetic anhydride in the presence of pyridine. X-ray crystal structure analysis shows that the three rings of the anthraquinone system are not coplanar because of steric inter­actions with the benzyl­idene group.

3,6-Bis(4-chloro­phen­yl)-1-isobutyr­yl-1,4-dihydro-1,2,4,5-tetra­zine

The title compound, C₁₈H₁₆Cl₂N₄O, was prepared from isobutyric anhydride and 3,6-bis­(4-chloro­phen­yl)-1,2-dihydro-1,2,4,5-tetra­zine. The central six-membered ring has a boat conformation.

Diethyl 1,4-dihydro-1,2,4,5-tetra­zine-3,6-dicarboxyl­ate

The title compound, C₈H₁₂N₄O₄, was prepared from ethanol and 1,4-dihydro-1,2,4,5-tetra­zine-3,6-dicarboxylic acid. The central six-membered ring has a boat conformation.

3-Hydr­oxy-17-oxoestra-3,5-dien-3-yl acetate

In the title steroid compound, C₂₀H₂₆O₃, rings A and B have screw boat conformations, ring C has a regular chair conformation and ring D approximates to a distorted half-chair conformation. The mol­ecules are connected via C—H...O hydrogen bonds, generating a two-dimensional network.

2-Methyl-2-nitro­propyl 3-(3,4-dihydroxyphenyl)prop-2-enoate

Crystals of the title compound, C₁₃H₁₅NO₆, were obtained from the modified Knoevenagel condensation reaction of 3,4-dihydroxy­benzaldehyde and mono-2-methyl-2-nitro­propyl malonate. The mol­ecule is the E isomer with the usual bond lengths and angles. The crystal packing is stabilized by inter­molecular O—H...O and C—H...O hydrogen bonds.

10-(3-Methoxy­benzyl­idene)anthrone

The title compound, C₂₂H₁₆O₂, was prepared from anthrone and 3-methoxy­benzaldehyde in the presence of pyridine. X-ray analysis shows that the anthraquinone ring system is not planar. The central six-membered ring adopts an asymmetric boat conformation, in which the carbonyl C and the para-C atoms deviate from the plane of the other four atoms by 0.162 (8) and 0.267 (8) Å, respectively. Inter­molecular C—H...O hydrogen bonds are present in the crystal structure.