2‐Hydro­xy‐5‐[(E)‐(4‐methoxy­phenyl)­diazenyl]­benzoic acid

The title compound, C₁₄H₁₂N₂O₄, shows an E conformation about the diazenyl N atoms. The crystal structure features layers of mol­ecules with the primary connection between the layers afforded by carboxyl­ic acid dimer motifs; no evidence for extensive π–π stacking between the layers was found.     

(E)‐1‐(2‐Hydro­xy‐4‐methoxy­phenyl)‐2‐(3,4,5‐tri­methoxy­phenyl)­ethene

In the crystal structure of the title compound, C₁₈H₂₀O₅, all geometric parameters fall within experimental error of the expected values. Analysis of the molecular‐packing plots reveals an infinite one‐dimensional linear array running parallel to the c axis, formed by an O—H⃛O intermolecular hydrogen‐bonding interaction. The stilbene framework and most of the substituents are approximately coplanar.     

1‐(2‐Hydro­xy‐4‐methoxy­phenyl)‐3‐(2,3,4‐tri­methoxy­phenyl)­prop‐2‐en‐1‐one

The title compound, C₁₉H₂₀O₆, crystallizes in the centrosymmetric space group P2₁/c with one mol­ecule in the asymmetric unit. The mol­ecule is approximately planar and the dihedral angle between the phenyl rings is 11.0 (1)°. The H atoms of the central propenone group are trans. There is an intramolecular O—H⃛O hydrogen bond and the mol­ecules are crosslinked by four intermolecular C—H⃛O hydrogen bonds, producing a three‐dimensional network.     

4‐[3‐(3,4‐Di­methoxy­phenyl)­prop‐2‐enoyl]­phenyl methacryl­ate and 4‐[3‐(2‐bromo­phenyl)­prop‐2‐enoyl]­phenyl methacryl­ate

Chalcones (α,β‐unsaturated ketones) are effective antitumour agents. It has been proved that having halogen or methoxy groups substituted in various positions of the phenyl ring enhances the activity of chalcones many times. The title compounds, C₂₁H₂₀O₅ and C₁₉H₁₅BrO₃, respectively, were chosen for crystallographic study in order to determine their structures and conformations. In both compounds, the keto group is in the s‐cis conformation and is almost planar. There are weak intramolecular interactions in both structures.     

(4S,5S)‐4‐[(1R)‐1,2‐Di­hydroxy­ethyl]‐5‐tri­decyl‐1,3‐oxazolidin‐2‐one

The title compound, C₁₈H₃₅NO₄, is a new bioactive amphiphilic lipid with a cis‐substituted 1,3‐oxazolidin‐2‐one head group. In the crystal structure, the mol­ecules form intercalating bilayers in which the oxazolidinone head groups are joined together by hydrogen bonds into chains.     

N‐(4‐Cyano­phenyl)‐α‐(4‐methoxy­phenyl)­nitro­ne

In the crystal structure of the title compound, 4‐cyano‐N‐(4‐methoxy­benzyl­idene)­phenyl­amine N‐oxide, C₁₅H₁₂N₂O₂, the 4‐methoxy­phenyl is approximately coplanar with the nitrone moiety but significantly rotated with respect to the 4‐cyano­phenyl moiety. The extent of this rotation is significantly different for the two crystallographically independent mol­ecules of the asymmetric unit [dihedral angles of 19.4 (1) and 26.5 (1)°]. The geometry about the C=N bond is Z. The two mol­ecules are related to one another by a pseudo inversion centre.     

(E,E)‐2,5‐Di­methoxy‐1,4‐bis­[2‐(3,4,5‐tri­methoxy­phenyl)­ethenyl]­benzene

In the title compound, C₃₀H₃₄O₈, molecular symmetry is coincident with crystallographic inversion symmetry. A three‐dimensional network is generated containing both C—H·π and C—H·n(O) interactions. A comparison of the geometry of this mol­ecule and the structure of a number of 2,4,6‐tri­methoxy‐substituted analogues is provided.     

(4R)‐3‐Allenyl‐4‐(di­phenyl­methyl)­oxazolidin‐2‐one,an unsubstituted allen­amide

The first X‐ray structure of an unsubstituted allen­amide, C₁₉H₁₇NO₂, is reported. The solid‐state phase supports the notion that a key minimum conformation of allen­amides can be invoked to rationalize the observed stereochemical outcomes in many of our methodological studies employing allen­amides. This minimum conformation involves two important factors, i.e. having approximate coplanarity between the planes of the oxazolidinone ring and the internal olefin, and having the allene moiety facing away from the carbamate carbonyl group. The C—N—C=C torsion angle that quantifies this approximate coplanarity between the plane of the oxazolidinone ring and that of the internal olefin, as determined from this crystallographic study, is −19.1 (2)°. A minimized structural calculation, which determined this angle to be −16.1°, is in close agreement. Additional structural features include a probable π–π interaction between the allene moiety and a benzene ring, and non‐classical hydrogen bonding in the form of weak C—H⋯O interactions that are responsible for the formation of two‐dimensional networks.     

N‐Benzyl‐N‐(4‐methoxy­phenyl)­cyclo­hex‐1‐ene­carbothio­amide

The crystal structure of the title thio­amide, C₂₁H₂₃NOS, was determined to investigate the relationship between the photostability in the solid state and the structure.     

(1R,2R,3S,4S)‐2‐[(2R,3S)‐2,3‐Di­methyl­oxiran‐2‐yl]‐3,4‐bis(4‐methoxy­benzyl­oxy)­cyclo­hexanol

The relative configuration was determined for the title com­pound, C₂₆H₃₄O₆, which was prepared in a synthetic study on immunosuppressant FR­65­814. There is an intra­mol­ecular hydrogen bond between the hydroxy and epoxy groups.     

(4S)‐3‐[(2R,3S)‐3‐Hydr­oxy‐2‐methyl‐3‐phenyl­propion­yl]‐4‐isopropyl­oxazolidin‐2‐one

The mol­ecule of the title compound, C₁₆H₂₁NO₄, is chiral and has three asymmetric centres. The absolute configuration was not determined via diffraction measurements on the crystal, but was established from the known absolute configuration of the starting material. In the crystal structure, the mol­ecules assemble through inter­molecular hydrogen bonds into a macrostructure with helical channels.     

N‐Benzyl‐N‐(2‐methoxy­phenyl)­cyclo­hex‐1‐ene­carbox­amide

The title amide, C₂₁H₂₃NO₂, (I), does not photocyclize in the solid state. The methoxy group is involved in intermolecular steric interactions and so prevents the rotation of the N‐phenyl group in the crystal.     

(2S,3S)‐2,6‐Dimethylheptane‐1,3‐diol,the oxygenated side chain of 22(S)‐hydroxycholestrol,and its synthetic precursor (R)‐4‐benzyl‐3‐[(2R,3S)‐3‐hydroxy‐2,6‐dimethylheptanoyl]‐1,3‐oxazolidin‐2‐one

(2S,3S)‐2,6‐Dimethylheptane‐1,3‐diol, C₉H₂₀O₂, (I), was synthesized from the ketone (R)‐4‐benzyl‐3‐[(2R,3S)‐3‐hydroxy‐2,6‐dimethylheptanoyl]‐1,3‐oxazolidin‐2‐one, C₁₉H₂₇NO₄, (II), containing C atoms of known chirality. In both structures, strong hydrogen bonds between the hydroxy groups form tape motifs. The contribution from weaker C—H...O hydrogen bonds is much more evident in the structure of (II), which furthermore contains an example of a direct short Osp³...Csp² contact that represents a usually unrecognized type of intermolecular interaction.     

3‐Benzyl‐2‐(4‐fluorophenyl)‐1,3‐thiazolidin‐4‐one

The title compound, C₁₆H₁₄FNOS, crystallizes with Z′ = 2 in the space group P2₁/c. In one of the two independent molecules, the heterocyclic ring is effectively planar, but in the other molecule this ring adopts an envelope conformation. The molecules are weakly linked by two C—H...O hydrogen bonds to form C₂²(14) chains. Comparisons are made with some symmetrically substituted 2‐aryl‐3‐benzyl‐1,3‐thiazolidin‐4‐ones.     

3‐[4‐(4‐Fluoro­phenyl)­piperazin‐1‐yl­methyl]‐5‐methyl‐1,3‐benzoxazol‐2(3H)‐one and 3‐[4‐(2‐fluoro­phenyl)­piperazin‐1‐yl­methyl]‐5‐methyl‐1,3‐benzoxazol‐2(3H)‐one

The title compounds, both C₁₉H₂₀FN₃O₂, contain essentially planar benzoxazolinone ring systems, within which the C—N bond distances and angles do not differ significantly between the two compounds. In both cases, the piperazine ring adopts an almost perfect chair conformation and the benzoxazo­l­inone ring system lies nearly perpendicular to it. The structures contain intermolecular C—H⋯O contacts, and the interactions between the benzoxazolinone and fluoro­phenyl­piperazine portions of the mol­ecules are segregated.     

Bis[4‐(3‐pyridylmethyl­eneamino)­phenyl]methane

In the title Schiff base compound, C₂₅H₂₀N₄, the two rigid parts adopt an angular conformation, thus making the compound a potential non‐linear ditopic ligand for the construction of interesting coordination polymers.     

1‐Chloro‐1,1‐di­fluoro‐N‐(4‐methoxy­phenyl)‐3‐(pyrrolidin‐2‐yl­idene)­propan‐2‐imine

In the title compound, C₁₄H₁₅ClF₂N₂O, the Z configuration has been confirmed. The molecular structure shows an intramolecular N—H?N hydrogen bond [H?N 2.04 (6), N?N 2.709 (6) Å and N—H?N 124 (5)°]. This interaction could be responsible for the Z configuration.     

Ethyl N‐[2‐(hydroxy­acetyl)­phenyl]­carbamate,ethyl N‐[2‐(hydroxy­acetyl)‐4‐iodo­phenyl]­carbamate and ethyl N‐[2‐(hydroxy­acetyl)‐4‐methyl­phenyl]­carbamate

In ethyl N‐[2‐(hydroxy­acetyl)phenyl]carbamate, C₁₁H₁₃NO₄, all of the non‐H atoms lie on a mirror plane in the space group Pnma; the mol­ecules are linked into simple chains by a single C—H⋯O hydrogen bond. The mol­ecules of ethyl N‐[2‐(hydroxy­acetyl)‐4‐iodo­phenyl]carbamate, C₁₁H₁₂INO₄, are linked into sheets by a combination of O—H⋯I and C—H⋯O hydrogen bonds and a dipolar I⋯O contact. Ethyl N‐­[2‐(hydroxy­acetyl)‐4‐methyl­phenyl]carbamate, C₁₂H₁₅NO₄, crystallizes with Z′ = 2 in the space group P; pairs of mol­ecules are weakly linked by an O—H⋯O hydrogen bond and these aggregates are linked into chains by two independent aromatic π–π stacking inter­actions.     

3‐(4‐Acetyl­phenyl)‐1‐(4‐nitro­phenyl)­triazene

The crystal structure of the title compound, C₁₄H₁₂N₄O₃, shows that the stereochemistry about the N=N double bond of the N=N—N(H) moiety is trans. The whole mol­ecule is almost planar (r.m.s. deviation = 0.0654 Å), the interplanar angle between the phenyl rings being 0.7 (1)° and the largest interplanar angle being that between the phenyl ring and the nitro group of the 4‐nitro­phenyl substituent [11.5 (2)°]. Intermolecular N—H⋯O interactions between mol­ecules related by translation give rise to chains along the [110] and [10] directions, and these chains are held together by N⋯O π–π interactions. An unequal distribution of the double‐bond character among the N atoms suggests a delocalization of π electrons over the diazo­amine group and the adjacent aryl substituents.     

1‐(4‐Bromo­phenyl)‐3‐(4‐methyl­phenyl)­prop‐2‐en‐1‐one

In the mol­ecule of the title compound, C₁₆H₁₃BrO, the two benzene rings are rotated in opposite directions with respect to the central C—C=C—C part of the mol­ecule. The phenone O atom deviates from the least‐squares plane of the mol­ecule by 0.300 (3) Å. In the crystal structure, mol­ecules are paired through C—H⋯π interactions. The molecular pairs along [001] are hydrogen bonded through three translation‐related co‐operative hydrogen bonds in the `bay area', forming molecular chains, which are further hydrogen bonded through C—H⋯Br weak interactions, forming (010) molecular layers. In the third direction, there are only weak van der Waals interactions. The co‐operative hydrogen bonds in the `bay area' are discussed briefly.