Asymmetric hetero-Diels-Alder reactions: X-ray structures of three novel chiral dihydropyrimidines

Three novel dihydropyrimidine compounds N8,6-di(4-nitrophenyl)-(3R)-ethyl-(7R)-methyl-5-oxo-2,3,6,7-tetrahydrooxazolo[3,2,c] pyrimidine-8-carboxamide (2), N8,6-di((4-methylphenyl)-sulfonyl)-(3R)-ethyl-5-oxo-(7R)-phenyl-2,3,6,7-tetrahydrooxazolo [3,2,c]pyrimidine-8-carboxamide (3) and N8,6-di ((4-methylphenyl)sulfonyl)-(3R)-ethyl-(7R)-methyl-5-oxo-2,3,6,7-tetrahydrooxazolo[3,2,c] pyrimidine-8-carboxamide (4) have been prepared (from 2-amino-1-butanol of 64.4% e.e.) and structurally characterized by X-ray crystallography. All three compounds contain stereogenic centers, but the crystal of (2) chosen was found to be racemic whilst those of (3) and (4) were found to be homochiral. Compound (2) crystallizes in the monoclinic space group P2₁/c, with a = 17.958(4), b = 12.431(2), c = 9.653(2) Å, = 96.20(3)°, U = 2142.3(7) ų, Z = 4, and D _c = 1.449 g cm^–3. Compounds (3) and (4) both crystallize in the monoclinic space group P2₁, with a = 9.349(2), b = 5.824(5), c = 26.513(8) Å, = 99.43(2)°, U = 1424.1(13) ų, Z = 2 and D _c = 1.389 g cm^–3 for (3), and a = 5.9526(9), b = 16.3521(10), c = 13.2263(11) Å, = 92.81(12)°, U = 1285.9(2) ų, Z = 2 and D _c = 1.378 g cm^–3 for (4).     

Crystal structures and conformations of two new biisoquinoline derivatives

Crystal structural studies of two new biisoquinoline derivatives, a neutral compound C₂₀H₂₄N₂ (3) and a salt C₁₈H₂₁N₂ ⁺C₁₀H₁₄BrO₄S^– H₂O (4) are described and discussed. Compound 3 crystallizes in the monoclinic space group P2 ₁/c, with a = 11.039(2), b = 7.791(2), c = 19.001(4) Å, = 104.31(3)°, and Z = 4. Compound 4 crystallizes in the monoclinic space group P2 ₁, with a = 12.0021(3), b = 8.9189(2), c = 12.8685(4) Å, = 100.7600(10)°, and Z = 2. The absolute stereochemistry of 4 in the solid state has been determined. The biisoquinoline rings in both compounds adopt twist-boat conformations with significant deviations from ideal geometry. The two heterocyclic rings in each species are oriented so that they are not overlayed with each other and the phenyl rings are oppositely directed. The cations and the anions in 4 are linked together through an elaborate system of hydrogen bonding involving the water molecule.     

Metal complexes of chiral pyridine ligands. X-ray structure of nitratobis {2-(2S)-2-pyrrolidinyl]pyridine} copper (II) nitrate

Cobalt(II), nickel(II), and copper(II) complexes of 2-[(2S)-2-pyrrolidinyllpyridine (L) have been synthesized and characterized. The crystal structure of the complex [Cu(L)₂(NO₃)]NO₃ has been determined by X-ray diffraction. Crystals are monoclinic, space groupP2+, witha=10.766(3).b=7.525(2),c=13.447(4) Å. =104.64(2)°. and Z=2. The structure consists of [Cu(L)₂(NO₃)]⁺ cations and NO ₃ ^t- anions. The copper atom has a distorted trigonal bipyramidal coordination geometry with the two pyrrolidine nitrogens and one nitrate oxygen occupying the equatorial positions and the two pyridine nitrogens at the apices. The crystalline cohesion is ensured by a network of hydrogen bonds involving the pyrrolidine groups as donors and both coordinate and uncoordinate nitrates as acceptors.     

The X-ray crystal structures of three bis(cyclopentadienyl)titanium(IV) derivatives

The X-ray crystal structures of (aqua)bis(cyclopentadienyl)chlorotitanium(IV) trifluoromethanesulfonate, bis(aqua)bis(cyclopentadienyl)titanium(IV) bis(trifluoromethanesul-fonate) and bis(cyclopentadienyl)bis(trifluoromethanesulfonato)titanium(IV) show a pseudo-tetrahedral array of Cp ring centroids and oxygen or oxygen and chloride donors around titanium, and varied long-range packing motifs dependent on the availability of hydrogen bond acceptors within the lattice.     

X-ray structural and spectroscopic investigation of 1-piperidine-2,4-dinitrobenzene

The crystal structure of the title compound (C₁₁H₁₃N₃O₄) has been determined by single-crystal X-ray diffraction. The compound is monoclinic, space group P2₁/n, witha=9.968(2),b=9.156(2),c=13.249(2)Å, =102.05(2)°, andD _x=1.563 gcm^–3 forZ=4. The aromatic ring shows a slight boat deformation. Theo- andp-NO₂ groups are twisted out of the plane of the phenyl ring by 39.0(2)° and 4.4(1)°, respectively. The piperidine ring exhibits a slightly deformed chair conformation. Short C–H...O intermolecular contacts stabilize the three dimensional structure. UV and NMR data indicate that the molecule in solution presents a conformation similar to that of the the solid state.     

Syntheses and crystal structures of two soybean isoflavone derivatives

Two soybean isoflavone derivatives, 7-methoxy-4′-hydroxyisoflavone (1) and 4′, 7-diethoxyl-5-hydroxyisoflavone (2) were synthesized and their crystal structures were determined by single-crystal X-ray diffraction. Two derivatives crystallize in the monoclinic crystal system, space group P2₁/c. The cell dimensions of 1 are a = 8.696(4) Å, b = 11.947(5) Å, c = 12.078(5) Å, β = 93.594(7)^∘, D_c = 1.423 Mg/m³, V = 1252.3(10) ų, Z = 4, and those of 2 are a = 37.672(12) Å, b = 11.228(4) Å, c = 7.582 (3) Å, β = 94.150(6)^∘, D_c = 1.355 Mg/m³, V = 3198.6(18) ų and Z = 8. They have the same isoflavone skeleton which is composed of a benzopyranone moiety and a phenyl moiety. Hydrogen bonding and π < eqid1 > π stacking interactions assemble 1 into supramolecule with a three-dimensional network. And in the crystal structure of 2, hydrogen bonding and C–H ⋅s π stacking interactions lead to the formation of a two-dimensional network.     

Solvothermal syntheses and crystal structures of two 4‐heterocyclic acylpyrazolone complexes

Many explorations of transition metal (M)‐L system under solvothermal condition, have led to the syntheses of two new 4‐heterocyclic acylpyrazolone complexes [Co(L)₂(CH₃OH)₂] (HL = 1‐phenyl‐3‐methyl‐4‐(2‐furoyl)‐5‐pyrazolone) ( 1 ) and [Cr(L)₃] ( 2 ). Single‐crystal X‐ray analyses reveal that crystal structures of compound 1 and 2 are respectively orthorhombic, Pbca, a = 15.0378(6) Å, b = 9.8405(4) Å, c = 20.7321(8) Å, V = 3067.9(2) ų, Z = 8 and triclinic, P‐1, a = 10.7966(18) Å, b = 13.023(2) Å, c = 15.520(3) Å, α = 73.011(4)°, β = 84.884(4)°, γ = 70.267(4)°, V = 1964.3(6) ų, Z = 2. Complex 1 has a two‐dimensional (2D) network structure that is formed by O–H···N H‐bonding interactions. Complex 2 makes a one‐dimensional (1D) zigzag chain structure by intermolecular π···π interactions, which is further interlinked via C–H···N H‐bonding interactions to generate a 2D sheet, and then a three‐dimensional (3D) supramolecular network structure is further linked by intermolecular C–H···π interactions. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Preparation,spectral studies and X-ray crystal structure of 1,3,5-triphenyl-1,5-pentanedione,C23H20O2

1,3,5-triphenyl-1,5-pentanedione, C₂₃H₂₀O₂, has been prepared and characterized by spectroscopic methods and single crystal X-ray analysis. Crystals are monoclinic, space groupP2₁/n, a=28.124(4),b=5.997(1),c=10.434(1)Å, -98.42(1)Å,Z=4. The structure has been refined to a finalR-value of 0.040 for 1625 reflections withF _o>3(F _o). The compound contains the two carbonyl groups in a mutuallycis arrangement.     

X-ray crystal structure and1H-NMR chiral shift reagent study of a crown trimer

3,4,5-Trimethoxybenzyl alcohol was cyclooligomerized with a bentonite clay used as a catalyst. Results of the crystal structure analysis of the racemic (±) nonamethoxy[1,1,1]orthocyclophane trimer, C₃₀H₃₆O₉, are described. The structure was determined by X-ray diffraction at 293 K and shown to belong to the triclinic space group P . The compound possesses a distorted crown conformation with unusual C–H...O intermolecular interactions, and with a crystal packing not observed before in other related derivatives. The racemic mixture was also discriminated in its two enantiomeric isomers, using proton NMR and Eu(III) as a chiral shift reagent.     

Syntheses and X-ray structures of new phenoxy imino compounds

Four new phenoxy imino compounds were synthesized, and the solid-state structures of 1–3 were determined by single-crystal X-ray diffraction study, giving crystallographic data as follows. 2-Acetyl-6-[1-(2,6-diisopropylphenylimino)ethyl]-4-methylphenol (1): a = 13.5893(5) Å, b = 10.5781(4) Å, c = 15.6778(4) Å, = 113.1804(18), P2₁/c. 2,6-[1-(2,6-Diisopropylphenylimino)ethyl]-4-methylphenol (2): a = 12.1909(5) Å, b = 16.3324(6) Å, c = 15.9456(7) Å, = 96.990(2), P2₁/c. 2-Acetyl-6-[1-(4-bromine-2,6-dimethylphenylimino)ethyl]-4-methylphenol (3): a = 7.5337(4) Å, b = 10.0457(5) Å, c = 12.6163(4) Å, = 90.139(3), = 104.003(3), = 106.485(2), P–1. Their molecular structures show that the 2,6-substituted phenyl ring is located approximately orthogonal to the hydroxyphenyl ring with the dihedral angle varying from 85.2 to 101.4.for X-ray Diffraction     

Synthesis and powder X-ray diffraction of new Schiff-base liquid crystal

Liquid crystals (LCs) are soft materials that combine the fluidity of disordered liquids and the long-range orientational or positional order of crystalline solids, along one or two directions of space. A search for better stationary phases, including highly selective ones, is an important trend in chromatography development. Among the stationary phases under investigation are LC stationary phases that have been recently generated much interest. A variety of isomeric molecules were separated with high accuracy. Successfully, X-ray scattering is widely used to investigate and characterise the microscopic structure of most LCs. In this paper, a new liquid crystalline material that can be used potentially as stationary phase in gas chromatography was synthesised and characterised by means of nuclear magnetic resonance (NMR), infrared (IR) spectra, elemental analysis and X-ray diffraction.     

The crystal and molecular structures of rac-threo-ifenprodil and two other 4-benzylpiperidinyl derivatives

The crystal structures of threo-ifenprodil [threo-2-(4-benzyl-piperidin-1-yl)-1-(4-hydroxyphenyl)-propan-1-ol] (1), potent NMDA receptor antagonist, and two related, biologically active compounds: threo-2-(4-benzyl-piperidin-1-yl)-1-(4-fluorophenyl)-propan-1-ol (2) and 4-benzyl-1-phenethyl-piperidinium chloride (3) have been determined by X-ray structure analysis of single crystals. Compound 1 crystallizes in an orthorhombic system, with a space group Pna2₁ (a = 34.843(3) Å, b = 6.0261(13) Å, c = 8.9343(9) Å), compound 2 – in a monoclinic space group P2₁/c (a = 14.194(1) Å, b = 6.2831(6) Å, c = 20.948(1) Å, = 101.762(6)), and compound 3 – in an orthorhombic space group Pbca (a = 10.4627(8) Å, b = 11.2166(6) Å, c = 31.669(2) Å). The piperidine rings are close to ideal chair conformations, the substituents are in equatorial positions. Overall shapes of the molecules, defined by the dihedral angles between the terminal aromatic rings, are very similar in all three cases. In 1 and 3 the crystal packing is mainly determined by the hydrogen bonds, while in case of 2 – by weak van der Waals interactions. The molecules of 1 and 3 are disordered, and the disorder is caused by a rotation around the N–C bond.     

The crystal and molecular structures of highly substituted cubanes: 1,2,4,7-tetra(carboxymethyl)cubane and 1,2,3,5,7-penta(carboxymethyl)cubane

The structures of the title compounds, 1,2,4,7-tetra(carboxymethyl)cubane 1 and 1,2,3,5,7-penta(carboxymethyl)cubane2, have been determined.1 crystallized in the space group with cell dimensionsa=6.098(2),b=10.686(2),c=13.459(2) Å, =69.82(1), =77.01(1), =74.00(1)°, while2 crystallized in the monoclinic space group P2₁/c with cell dimensionsa=15.139(2),b=12.775(1),c=9.849(2) Å, =107.01(1)°. These molecules were derived from their parent carboxylic acids by esterification with methanol. They are unusual for several reasons. The first is that they both contain substituents on adjacent carbon atoms in the cubane framework. There are only a few reports in the literature of this type of cubane structure. The second molecule is unique in that it has five substituents attached to a cubane moiety. This is the one of the few cubane derivatives with more than four substituents to be structurally characterized and results in a cubane molecule in which there are three faces with three substituents and three faces with only two substituents.     

Crystal and molecular structures of derivatives formed by reaction between toluenesulfonhydrazide and D-glucose, D-galactose, and L-arabinose

Derivatives formed by reaction of toluenesulfonhydrazide with D-glucose, D-galactose, and L-arabinose are shown by X-ray crystal structure analysis to be N-glycosides rather than open-chain hydrazones in the solid state. All three sugar derivatives assume the ⁴C₁ pyranosyl form, and in all three cases the orientation of the N-glycosidic linkage is equatorial. The gauche conformation of the glucoside and galactoside at the N(2)–N(1)–C(1)–C(2) linkage allows formation of an intramolecular hydrogen bond between the O(2) hydroxyl group and a sulfonyl oxygen atom, but no corresponding intramolecular interaction is found in the arabinoside due to its trans conformation at this linkage. In both the galactoside and arabinoside an S–O bond is eclipsed with the phenyl ring, but in the glucoside the phenyl ring assumes a staggered orientation with respect to the S–O bonds. Intermolecular hydrogen bonding interactions bind the molecules together to form alternating layers of hydrophilic groups (the pyranosyl rings) and hydrophobic groups (the aryl rings) in the crystal.     

Syntheses and crystal structures of two new cobalt(II) complexes derived from 3,5-bis(pyridin-2-yl)-4-amino-1,2,4-triazole

Two different cobalt(II) complexes have been synthesized from room-temperature solution reaction or solvothermal reaction of CoCl₂, KSCN, 3,5-bis(pyridin-2-yl)-4-amino-1,2,4-triazole and MeOH. X-ray crystallography shows that the product obtained at ambient temperature is a mononuclear species, while the product obtained by solvothermal method is a dinuclear complex incorporating an in situ deaminated ligand.     

Syntheses and crystal structures of an organometallic thiosemicarbazone and an organometallic enehydrazide

Reactions of ferrocenoylacetone with thiosemicarbazide and isonicotinic acid hydrazide generate an organometallic thiosemicarbazone 1 and enehydrazide 2, respectively. The complexes 1 and 2, which can be formulated as [C₅H₅FeC₅H₄C(O)CH₂C(=NNHCSNH₂)CH₃] and [C₅H₅FeC₅H₄C(O)CH=C(NHNHCOC₅H₄N-4)CH₃], have been characterized by elemental analyses, IR, NMR, UV and were structurally characterized by single-crystal X-ray crystallography. Complex 1 (C₁₅H₁₇FeN₃OS) crystallizes in the monoclinic space group P2₁/c, with lattice constants: a = 13.939(3) ?, b = 8.2600(17) ?, c = 13.176(3) ?, β = 94.83(3)°, V = 1511.7(6) ?³, Z = 4, D _c = 1.508 g cm⁻³, F(000) = 712, R ₁ = 0.0602, wR ₂ = 0.1526. Two intermolecular hydrogen bonds N–H···S (N···S = 3.356(8) and 3.499(7) ?, N–H···S = 168 and 170°) form a chain in the [010] direction. The intermolecular hydrogen bond C–H···O (C···O = 3.432(10) ?, C–H···O = 151°) leads to a [010] double-chain through each unit cell. The intermolecular hydrogen bond C–H···O (C···O = 3.359(10) ?, C–H···O = 173°) makes the [010] double-chain pack along the c axis to result in a two-dimensional network. Complex 2 (C₂₀H₁₉FeN₃O₂) crystallizes in the monoclinic space group P2₁/c, with lattice constants: a = 14.091(2) ?, b = 10.024(2) ?, c = 13.806(2) ?, β = 112.41(2)°, V = 1802.8(6) ?³, Z = 4, D _c = 1.434 g cm⁻³, F(000) = 808, R ₁ = 0.0576, wR ₂ = 0.1593. The strong intramolecular hydrogen bond N–H···O from the enamine N atom and carbonyl O atom stabilizes the enehydrazide. The intermolecular hydrogen bonds N–H···O and C–H···O (N···O = 2.906(6) ?, N–H···O = 155° C···O = 3.364(6) ?, C–H···O = 153°) generate a [010] chain. The intermolecular hydrogen bond N–H···O (N···O = 2.989(6) ?, N–H···O = 128°) forms a [010] double-chain through each unit cell. The π···π stacking interation involving the pyridyl groups makes the [010] double-chain pack along the c axis to lead to a two-dimensional network.     

The crystal and molecular structures of isoperezone, aminoperezone, and isoaminoperezone: a comparative study of their crystal packing

The crystal structures of isoperezone (1), aminoperezone (2), and isoaminoperezone (3) have been determined by single-crystal X-ray diffraction. Compound (1) yields orange crystals, orthorhombic space group P2₁2₁2₁ with unit cell dimensions a = 6.271(6), b = 30.373(7), c = 7.257(1) Å, and Z = 4; compound (2) yields purple crystals, orthorhombic space group P2₁2₁2₁ with unit cell dimensions a = 6.498(3), b = 7.500(1) c = 29.200(6) Å, and Z = 4; compound (3) yields purple crystals, monoclinic space group P2₁ with unit cell dimensions a = 7.354(1), b = 7.511(1), c = 13.283(1) Å, = 102,07(1)°, and Z = 2. The side chains in (1)–(3) are oriented out of the plane of the quinone ring at an angle of 124, 144, and 97°, respectively. The molecules in the crystal are held together by hydrogen-bonding networks and van der Waals interactions.     

Synthesis, characterization, and crystal structures of two strained cyclic diacetylenes and their precursors

The synthesis, characterization, and crystal structures of two novel strained cyclic diacetylenes are reported. A discussion is presented about the relative bond distances of the diacetylenes compared to a previously reported strained cyclic diacetylene to further determine the degree of aromaticity of that compound. 1,2:5,6:9,10:13,14-Tetrabenzo-3,7,11,15,17-pentadehydro[18] annulene (5) is triclinic, P ^–1, with = 9.489(5), b = 10.550(5), c = 12.155(6) Å, = 100.50(4), = 106.50(4), = 100.85(4)°. 1,2:5,6:9,10:13,14:17,18-Pentabenzo-3,7,11,15,19,23,25-heptadehydro[26]annulene (7) is triclinic, P ^–1, with a = 9.611(2), b = 10.388(3), c = 15.963(3) Å, = 88.67(2), = 76.25(1), = 68.69(2). In addition, two precursors of 5, 3 and 4 which have a helical twist, are reported. [1,2-ethynediyl-bis(2,1-phenylene-2,1-ethynediyl-2,1-phenylene-2,1-ethynediyl]bis[trimethyl-silane] (3) is monoclinic, P2₁/c, with a = 13.682(4), b = 9.787(2), c = 13.448(4) Å, = 112.37(2)°. 1,1-(1,2-ethynyldiyl)bis[2-[(2-ethynylphenyl)ethynyl]-benzene (4) is monoclinic, P2₁/n, with a = 15.951(3), b = 3.999(1), c = 18.168(4) Å, = 99.05(3)°.     

Synthesis, crystal structures, and properties of two manganese(II)-nitroprusside complexes

Two new manganese(II)-1,10-phenanthroline-nitroprusside complexes, [Mn(phen)₃][Fe (CN)₅(NO)]⋯2H₂O⋯0.25CH₃OH (1) and [Mn(phen)₂(H₂O)₂][Fe(CN)₅(NO)]⋯H₂O (2) (where phen is 1,10-phenanthroline) have been synthesized and characterized by X-ray diffraction, electronic paramagnetic resonance (E.P.R.) and IR analyses. Complex 1 crystallizes in the monoclinic space group P2₁/n, with lattice parameters a = 10.0441(15) Å, b = 19.668(2) Å, c = 19.938(3) Å,  β =100.427(14)°, V = 3873.7(10) ų, Z = 4; complex (2) crystallizes in the monoclinic space group C2/c, with a = 17.120(2) Å, b = 13.7925(19) Å, c = 14.4362(17) Å, β = 107.962(12)°, V = 3242.6(7) ų, Z = 4. In the two compounds, three phen ligands 1, or two phen ligands and two cis-related aqua molecules 2, are in a distorted octahedral arrangement around the Mn(II) ion. The nitroprusside anion, [Fe(CN)₅(NO)]²⁻, acts as a counterion. It is intriguing that in complex 2 no cyano bridges are present with two water molecules coordinated to the Mn(II) ion considering that usually the cyano nitrogen atoms are strong donors and could readily replace the coordinating solvent water molecules. Abundant hydrogen bond interactions and π–π stacking between the phen rings in two complexes lead to three-dimensional supramolecular networks.