Preparation and crystal structure of spiro(5,7-dimethoxy-1(1H)oxo-2-benzopyran-3(4H),1′-cyclohexane)

Spiro(5,7-dimethoxy-1(1H)oxo-2-benzopyran-3(4H),1-cyclohexane) (C₁₆H₂₀O₄) was prepared by alkylation of o-lithio 3,5-dimethoxy-N-methyl benzamide with methylene cyclohexane oxide followed by alkaline hydrolysis and its crystal structure was determined by X-ray crystallographic techniques. The compound crystallizes into monoclinic space group P2₁/c with unit cell parameters: a = 11.914(3) Å, b = 9.861(3) Å, c = 12.508(7) Å, = 91.34(3), Z = 4. The structure has been solved by direct methods and refined to R = 0.039 for 1870 observed reflections. The heterocyclic ring adopts distorted sofa conformation while cyclohexane ring assumes a highly symmetric chair conformation. The dihedral angle between the mean planes of isocoumarin nucleus and cyclohexane ring is 105.51(5). Molecules are held together in the crystal by C=H ... O hydrogen bonds.     

Crystal and molecular structure of isovoacangine: An alkaloid from Stemmadenia Donnell-Smithii

C₂₂H₂₈N₂O₃ is monoclinic,P2₁. Unit-cell dimensions at 293 K area=10.023(5),b=6.615(3),c=14.749(6) Å,=91.41(4)°,V=978(1) ų,D _c =1.25 g cm^–3, andZ=2. The structure has been determined from single-crystal data collected with a four-circle diffractometer and refined from 1421 reflections toR=0.057. The structural features determined from chemical and spectroscopic studies are confirmed and extended. The stereochemistry at C(4) and C(18) is 4S and 18S. The indole ring is not planar and the seven-membered nitrogen-containing ring adopts a distorted-chair conformation. The angle between the normals to the planes of the indole and sevenmembered rings is 15.2(1)°, while the C(5)-N(6)-C(19)-C(2) atoms of the central axis of the iso-quinuclidine tricyclic structure is 69.1(1)°. The molecules in the crystal are held together by a hydrogen bond, a C-HO contact, and van der Waals interactions.     

X-ray diffraction structure of (5S)-3,4-dichloro-5-menthoxy-2(5H)-furanone

The structure of (5S)-3,4-dichloro-5-menthoxy-2(5H)-furanone is reported. The title compound crystallizes in the monoclinic space group P2₁: a = 6.650(2) Å, b = 8.038(3) Å, c = 14.858(8) Å, = 97.01(3), V = 788.3(6) ų, Z = 2, R = 0.0718, R _w = 0.0795 for 735 observed reflections with I > 3 (I), and the absolute configuration at C-5 of the furanone ring is shown to be (S).     

Absolute configuration of (−)2-dibenzofurylmethylsulfinylacetic acid

The crystal structure and the absolute configuration of the title compound has been determined from single-crystal X-ray diffraction data. The monoclinic unit cell (space group P2₁) witha=11.514(2),b=8.288(1),c=13.749(2) Å, =99.69(1)° andZ=4 contains two crystallographically independent molecules. The configuration at the sulfur atom in both molecules is S. A large lability of the methoxysulfinylacetic group conformation and configuration is observed. The conformations and S–C_sp ³–C_sp ² _(phen) bond angles of this group in two independent molecules are distinctly different. The comparison of the investigated compound with the literature data of related molecules is given.     

Crystal and molecular structure of acanthothamine monohydrate-methanol: A new alkaloid from Acanthothamnus aphyllus

C₃₄H₄₃O₁₆N·CH₃OH·H₂O is monoclinic,C ₂ ² -P2₁. Unit cell dimensions at 293 K area=9.159(3),b=17.017(5),c=13.675(5) Å,=109.49(2)°,V=2009(1) ų,D _c =1.28 g cm^–3, andZ=2. The structure has been determined from single-crystal data collected with a four-circle diffractometer and refined from 2367 reflections down toR=0.064 andR=0.082. The structural features determined from chemical and spectroscopic studies are confirmed and extended. The absolute configuration was determined by comparison with known absolute stereochemistry of the bromoacetylneoevonine monohydrate. The acanthothamine molecule is an evonine and neoevonine analogue showing an epimeric configuration at C(17) of the evoninic acid residue. The A and B rings adopt chair conformations. The C ring has a half-chair conformation. The crystal structure is stabilized by a three-dimensional network of hydrogen bonds and a number of intramolecular C-HO and C-HN interactions.     

Structure, absolute configuration, and conformation of the antimalarial compound, Artemisinin

The crystal and molecular structure of the antimalarial compound Artemisinin (formerly known as Qinghaosu), C₁₅H₂₂O₅ has been determined by direct methods. Crystals are orthorhombic colorless needles, space group P2₁2₁2₁, Z = 4. D _c = 1.299 g cm ^–3, with unit cell parameters a = 6.3543(9), b = 9.439(3), c= 24.066(4) Å. The molecule incorporates a fused ring system containing a six-membered ring C which includes an oxygen bridge and a peroxy-bridge. The ring C has a distorted boat conformation and the C - O - O - C torsion angle is 47.8(2)°. Rings A and D have symmetrical chair and distorted chair conformations, repectively. Ring junctions A/B, A/D, and C/D are cis, junction B/D is trans. All inter-molecular contacts are van der Waals. The absolute configuration of Artemisinin was determined from the refined value of the Flack x parameter. [The atomic coordinates given in a previous structure analysis, Crystal Structure and Absolute Configuration of Qinghaosu, Qinghaosu Research Group, Institute of Biophysics, Academica Sinica, Scientia Sinica, Vol. XXIII No. 3, 380 (1980), do not display the molecule in its absolute configuration.]     

Crystal and molecular structure of 1-epi-delphisine and nmr assignments for delphisine, 1-epi-delphisine and delphinine

The crystal and molecular structure of the norditerpenoid alkaloid 1-epi-delphisine (5), C₂₈H₄₃NO₈, M _r 521.66, has been confirmed by as X-ray diffraction study using the SIR 88 analysis program. The alkaloid crystallizes in the space groupP2₁ with cell parameters:a=11.853(1)Å,b=10.511(1)Å,c=11.854(1)Å,=112.58(1),V=1363.61(0)ų,Z=2,D _calc=1.27 g/cm³, (CuK)=1.54184 Å, (CuK=7.2 cm^–1,F(000)=564, temperature 23°C,R=0.052, for 2907 reflections. Ring A of 1-epi-delphisine exists in a chair conformation. By comparison, delphisine which bears a C-1 hydroxyl group, has ring A in a boat conformation stabilized by an intramolecular N----H-O hydrogen bond. Ring D of both of these alkaloids exists in a boat form. Unambiguous proton and carbon-13 nmr assignments for delphisine, 1-epi-delphisine and delphinine have been made by a detailed analysis of the DEPT, COSY, HETCOR, COLOC, DIFNOE, and selective INEPT nmr techniques.Dedicated to the memory of Dr. K. Krishna Bhandary (1946–1992).     

1,4-Di-[2-phenyl-1-diazenyl]perhydro-1,4-diazepine: X-ray crystal structure

1,4-Di-[2-phenyl-1-diazenyl]perhydro-1,4-diazepine (1) has been synthesized by reaction of benzenediazonium chloride with homopiperazine (perhydro-1,4-diazepine). The crystal structure of 1 has been determined by single crystal X-ray diffraction analysis. The bis-triazene (1) adopts an extended conformation which precludes any close intramolecular interaction of the phenyl rings. The heterocyclic seven-membered ring adopts a chair conformation, with the triazene side chains occupying alternate axial and equatorial positions consistent with cis-geometry. Internal torsion angles of the seven-membered ring have been measured. The crystal packing is determined by short contacts between C=H groups of phenyl rings and nitrogens of triazene moieties and by van der Waals interactions, with no evidence for intermolecular – interactions. This work establishes the structure of the product of diazonium coupling with homopiperazine as 1,4-di[(E)-2-phenyl-1-diazenyl]perhydro-1,4-diazepine. Crystal data: 1 C₁₇H₂₀N₆, monoclinic, space group P2₁/n, a = 9.1838(5) Å, b = 12.1095(6) Å, c = 15.0081(8) Å, = 101.320(2), V = 1636.6(2) Å,³ for Z = 4.     

Structure of 6,13-bis(<Emphasis Type="Italic">N</Emphasis>, <Emphasis Type="Italic">N</Emphasis>-dimethylcarbamoyl) thioquinanthrene

The crystal structure of 6,13-bis-(N,N-dimethylcarbamoyl)thioquinanthrene 3 has been determined as monoclinic, with space group P2(1)/c with lattice parameters a = 10.044(2) Å, b = 21.385(4) Å, c = 10.889(3) Å, = 102.92(3)°, Z = 4 and D_calc = 1.342 Mg/m³. The middle 1,4-dithiin ring in the title compound 3, C₂₄H₂₀N₄O₂S₂ is in a boat conformation with the dihedral angle between the planes of the aromatic rings 132.45(8)°.     

Crystal and molecular structure of ibogamine: An alkaloid fromStemmadenia galeottiana

C₁₉H₂₄N₂ is orthorhombic,D ₂ ⁴ -P2₁2₁2₁. Unit cell dimensions at 293 K area=10.346(7),b=10.464(3),c=29.083(10)Å,V=3149(4) ų,D _c =1.18 g cm^–3, andZ=8. The structure has been determined from single-crystal data collected with a four-circle diffractometer and refined from 1968 reflections down toR=0.045 and R=0.047. The structural features determined from chemical and spectroscopic studies are confirmed and extended. There are two crystallographically independent molecules (A and B). In both A and B molecules the indole ring system is planar and attached to a seven-membered nitrogen-containing ring with a distorted-chair conformation. The indole and seven-membered rings lie close to the same plane [dihedral angles are 6.6(5) and 4.1(5)° for the A and B molecules, respectively], while the C(5)-N(6)-C(19)-C(2) atoms of the central axis of theiso-quinuclidine tricyclic structure are almost perpendicular to seven-membered ring [dihedral angles are 84.7(5) and 87.9(5)° for the A and B molecules, respectively]. The A and B molecules in the crystal are packed at normal van der Waals distances.     

The pseudoguaianolide isoconfertiflorin

The sesquiterpene lactone isoconfertiflorin, C₁₇H₂₂O₅, 1, crystallizes in trigonal space group P3₁ with a = 10.4498(5), c = 12.7516(8) Å, V = 1205.9(2) ų, and Z = 3. It differs from confertiflorin in having an endocyclic C=C bond in the lactone ring, which carries an exocyclic methyl group. The seven-membered ring adopts an approximate twist-chair conformation with C10 lying in the local two-fold axis, and asymmetry parameter C₂ = 5.8°. The cyclopentanone ring has the half-chair conformation with C4 on the local two-fold axis, and C₂ = 0.9°. The lactone ring is almost planar with maximum deviation 0.014(2) Å. Both methyl groups on the 7-membered ring are –oriented. The acetyl group at C8 has an orientation.     

Crystal and molecular structure of (2E,4S,10R)-4-hydroxy-2-undecen-10-olide (nor-patulolide C), C11H18O3

The stereogeometry and absolute configuration of the title compound has been proved by an X-ray diffraction analysis. Crystal data: monoclinic, P2₁,a=7.7976(2),b=7.8288(2),c=8.9791(4) Å, =90.331(4)^o, Z=2. The crystal structure has been solved by vector search methods and refined toR=0.042 for 1798 observed reflections.     

Synthesis and crystal structures of 2-amino-3-cyano-4-(2-chlorophenyl)-1,4-dihydro-2H-pyrano[3, 2-h]quinoline and 2-amino-3-cyano-4-(2-chlorophenyl)-8-(2-chlorobenzylidene)-1,4,5,6,7,8-hexahydrobenzo[b]pyran

The title compounds 2-amino-3-cyano-4-(2-chlorophenyl)-1,4-dihydro-2H-pyrano[3, 2-h]quinoline 1 (C₁₉H₁₂ClN₃O, M _r = 333.77) and 2-amino-3-cyano-4-(2-chlorophenyl)-8-(2-chlorobenzylidene)-1,4,5,6,7,8-hexahydrobenzo[b]pyran 2 were synthesized and crystallized. The crystals of compound 1 are triclinic, space group P-1, a = 7.488(2), b = 9.127(3), c = 12.252(3) Å, = 73.58(2), = 78.38(2)°, = 75.39(2), Z = 2, V = 769.5(4) ų; The compound 2 crystallizes in space group P2₁/n, with cell parameters a = 13.582(2), b = 8.974(1), c = 16.960(2) Å, = 103.34(1)° and D _calc = 1.352 g/cm^–3 for Z = 4. X-ray analysis reveals that atoms C(1)—C(5) and O form a pyran ring in compound 1, which adopts half-chair conformation. In compound 2 the atoms C(12)—C(16) and O form a pyran ring which adopts boat conformation, another six-membered ring (C(8)—C(13)) adopts a half-chair conformation. In addition, there are intermolecular hydrogen bonds in the crystal structures 1 and 2.     

Crystal and molecular structure of delsoline

The crystal and molecular structure of the diterpenoid alkaloid delsoline (1) C₂₅H₄₁NO₇, M_r 467.61, has been determined by an X-ray analysis. The X-ray crystal structure which could not be solved earlier withMultan, has now been solved using the SIR 88 analysis program. The compound crystallizes in the space groupP2₁2₁2₁ with cell parameters:a=12.529(2),b=13.118(1),c=14.231(6)Å,V=2339(1)ų,Z=4,D _calc=1.33 g/cm^–3, (CuK)=1.54184 Å,(CuK )=7.4 cm^–1,R/R _w =0.068/0.040 for 2539 reflections. The A ring of delsoline exists in the boat conformation stabilized by an intramolecular N---H-O hydrogen bond. Ring D also is in a boat form. Unambiguous proton and carbon-13 nmr assignments have been made by a detailed analysis of the DEPT, COSY, NOESY, and HETCOR nmr spectra.     

Crystal structure and conformation of Linomide [N-methyl-N-phenyl-1,2-dihydro-4-hydroxy-1-methyl-2-oxo-quinoline-3-carboxamide]: A novel immunomodulator

Linomide [N-methyl-N-phenyl-1,2-dihydro-4-hydroxy-1-methyl-2-oxo-quinoline-3-carboxamide] is a new immunomodulator from Phamacia Laboratories, Helsingborg, Sweden. Linomide (LS-2616) has delayed hypersensitivity in rat skin, potentiates mouse natural killer cell activity, and stimulates polyclonal T-cell activation. It has been shown that LS-2616 abolishes the effects of continuous cyclosporine treatment in experimental models. Crystal structure of LS-2616 has been undertaken as a first step in the establishment of a possible structure–function relationship for the drug. Crystals of LS-2616 (C₁₈H₁₆N₂O₃) obtained from methylene chloride are monoclinic, of space group P2₁/a with the following crystallographic parameters: a = 8.793(1) Å, b = 22.349(3) Å, c = 7.808(1) Å, = 92.96(1)°, V = 1532.3(6) ų, _obs = 1.34 Mg/m³, _calc = 1.337 Mg/m³, and Z = 4. The structure was solved with CAD-4 data using MULTAN programs and refined to a final R value of 0.041. The N-methyl carboxamide is in the cis configuration and is turned away from the quinoline ring by 87°. FK506 is a novel 23-membered macrolide lactone which is currently used for bone marrow and organ transplantations. The crystal structure of FK506 has been published. The absolute configuration of FK506 was established as a cis-amide which contains a L-pipecolic acid moiety. Preliminary modeling studies of FK506 with LS-2616 revealed that this cis conformation for the N-methyl carboxamide leads to a lower binding energy than the corresponding trans conformation. The plane of the phenyl group is inclined by 95° to the carboxamide plane. The molecule has the familiar herring-bone type of packing, characteristic of the polyphenyl molecules, stabilized by O–H O and C–H O hydrogen bonds involving the hydroxyl group and the ketone substituents on the quinoline ring and the N-methyl group of the carboxamide.     

Investigations of dehydroepiandrosterone. Part I: crystal structure of sublimed DHEA

The crystal structure of an orthorhombic polymorph of the title compound, crystallized by sublimation, has been determined. Dehydroepiandrosterone, C₁₉H₂₈O₂, space groupP2₁2₁2₁ witha=6.6408(4)b=11.4423(11)c=22.085(2)Å,V=1678.2(4)ų,Z=4. The structure was refined toR=0.051 for 2645 observed reflections. The conformation of the molecule is similar to that found in other polymorphs and solvates, with a chair A ring, an 8, 9 half-chair B ring, a chair C ring, and a 14 envelope D ring. Molecules are linked in chains by OH...O hydrogen bonds involving the carbonyl oxygen atom. The O...O distance is 2.855(3) Å, and the angle about H is 171(2)^o.     

Crystal structure and absolute configuration of yohimbine hydrochloride,C21H27ClN2O3

Yohimbine (C₂₁H₂₆N₂O₃) is an important indole alkaloid found in the Indian snake rootrauwolfia serpentina, and is very closely related to reserpine. Yohimbine hydrochloride (C₂₁H₂₇ClN₂O₃) is orthorhombic:P2₁2₁2₁,a = 11·54,b = 24·88,c = 7·00 Å,Z = 4. X-ray diffraction data to a Bragg angle of 80 ° were collected on a G.E. diffractometer using CuK radiation. The structure was solved by direct methods, and refined to a reliability index of 9·9 % by the block-diagonal least-squares method. Yohimbine has a ring system very similar to that of reserpine, though the conformations of the ringsC andD about the C—N bond are different in the two molecules. The absolute configuration of the molecule, determined by X-ray anomalous scattering, confirms the 3, 15, 20 configuration assigned earlier by conformational analysis.     

Crystal and molecular structure of aN(2)-benzyl-1,3-disubstituted-1,2,3,4-tetrahydro-β-carboline

(1R,3S)-2-Benzyl-3-methoxycarbonyl-1-methylcarboxymethyl-1,2,3,4-tetrahydro-9H-pyrido [3,4-b] indole, C₂₃H₂₄N₂O₄, was synthesized by a modified Pictet-Spengler reaction, and its crystal and molecular structure determined by single crystal X-ray diffraction methods. The crystals are monoclinic:P2₁ (No. 4),a=11.336(1),b=8.919(1),c=10.314(1)Å,=100.81(1)°,Z=2. The structure has been solved by direct methods, and refined toR=0.041 for 2203 observed reflections. The six-membered heterocyclic ring is in a half-chair conformation, and the substituents at C(3) and C(5) occupy axial and equatorial positions respectively. The CH₂Ph group attached to N(4) is in the generally less favoured axial position. The nitrogen atom of the indole system forms an intermolecular hydrogen bond with the carbonyl oxygen of the CH₂CO₂ Me group, the NO distance being 2.995(3)Å.     

Crystal structures of two 1,2-bis-(1-aryl-3-methyltriazene-3-yl-)ethanes with aryl substituents of opposite polarity

The crystal and molecular structure of 1,2-bis-{1-(2-cyanophenyl)-3-methyltriazen-3-yl-}ethane (1) and 1,2-bis-{1-(2-methoxyphenyl)-3-methyltriazen-3-yl-}ethane (2) have been determined by single crystal X-ray diffraction analysis. Bis-triazene (1) exists as the staggered conformation in the solid state, with an anti-anti configuration around the N2–N3 bond of the triazene units, whereas 2 assumes a gauche conformation with the syn-syn configuration in the triazene units. Crystal data: 1 C₁₈H₁₈N₈, triclinic, space group P –1, a = 6.108(2), b = 8.118(3), c = 9.600(4)Å, = 101.37(7)°, = 96.47(7)°, = 102.71(5)°, V = 449.1(3)ų, Z = 2; 2 C₁₈H₂₄N₆O₂, monoclinic, space group P 2₁/n, a = 13.119(5), b = 7.745(2), c = 19.201(2)Å, = 96.47(7)°, V = 1910.3(9)ų, Z = 4.     

Solid state structure of 4,4,6,6-tetraphenylcyclohex-2-en-1-one

Synchrotron data allowed the crystal structure determination of 4,4,6,6-tetraphenylcyclohex-2-en-1-one (1). The cyclohexenone ring is in a half-chair conformation ³H₂violating the planarity of a conjugated -system. The geometry of 1 optimized with semiempirical and density functional theory calculations is in good agreement with the experimental data. Compound 1 crystallizes in triclinic space group with unit cell parameters a = 9.7995(19) Å, b = 10.5263(32) Å, c = 12.2001(37) Å, = 96.916(10)°, = 112.971(10)°, = 102.589(10)°, V = 1100.86(17) ų, and Z = 2.