Crystal and molecular structure of 1,4-diphenyl-2,3-dioxabicyclo[2,2,1] heptane,C17H16O2

The crystal structure of 1,4-diphenyl-2,3-dioxabicyclo [2,2,1] heptane has been determined from three-dimensional counter data and refined by full-matrix least-squares procedures. This endoperoxide compound crystallizes from ethanol in space groupP2₁/c with cell constantsa = 11.797(1),b = 9.051(8),c = 12.472(1) Å, = 93.78(1) °,Z = 4,D _x = 1.261, andD _m = 1.274 g cm^–3. The final residual for 2238 observed reflections is 0.063. The molecular structure possesses both an unusually long peroxide bond, 1.501(2) Å, and adjoining C-O bonds, 1.459(2) Å. This observation confirms a previously made conjecture that the forcedcis coplanarity of the C-O-O-C torsion angle would permit repulsive antisymmetric vicinal orbital interactions between the oxygen centers, destabilizing the peroxide bond relative to that normally encountered as the commonly observedgauche conformation.     

Structure of a potent neuromuscular blocking agent: Caracurine-II dimethochloride octahydrate, [C40H44N4O2]2+·2CI−·8H2O

Crystals of this calabash curare alkaloid, space groupP2₁; havea=12.695(4), Å,b=7.424(2) Å,c=21.762(6) Å,=98.03(5)°,Z=2,F(000)=884. The structure was solved by direct methods and refined by least squares toR=0.10. The alkaloid cation, with two-fold molecular symmetry, has a highly fused ring system and is structurally rigid. This determination provides accurate stereochemical parameters for those atoms and groups (N⁺ centers, aromatic rings, and hydrogen bond acceptors) postulated by various theories as involved in binding to the acetylcholine receptor. In the crystal, layers of alkaloid cations parallel to thebc plane alternate with layers containing two Cl^– ions and eight water molecules distributed almost randomly over ten sites. Electrostatic attractions between N⁺ and Cl^– bind the alternating layers together. Each one of the ten sites is, on average, 4.60 Å from one or two N⁺, allowing the two Cl_– ions to be disordered. Binding interactions within the alkaloid layers are solely van der Waals attractions. Within each H²O/C1^– layer there is a complex hydrogen bond system, including four infinite spirals parallel to theb axis, with an average bonding distance of 2.94 Å. There are no hydrogen bonds between layers. The possible relevance to the activity of the alkaloid of its ability to organize large amounts of water is discussed.     

Crystal Structure of Ethyl (2Z, 5R)-2-benzylidene-7-methyl-3-oxo-5-phenyl-2,3-dihydro-5H-[1,3] Thiazolo [3,2-a] Pyrimidine-6-carboxylate

Abstract  

The title compound, C₂₃H₂₀N₂O₃S, (I), crystallizes in the orthorhombic space group, Pna 2 ₁ , with cell parameters a = 18.7975(6), b = 12.5173(4), c = 8.4804(3) Å, Z = 4. The molecular structure consists of a central pyrimidine ring which is significantly puckered to assume a screw-boat conformation fused to a thiazole ring with benzyl, carboxylate, methyl, phenyl and oxy groups bonded around this fused-ring moiety. The dihedral angle between the mean planes of the thiazole, benzyl and phenyl groups and the mean plane of the pyrimidine ring is 6.1(4)°, 83.8(7)° and 6.8(4)°, respectively. The dihedral angle between the mean planes of the benzyl and phenyl rings is 88.3(5)° while between the mean planes of the phenyl and thiazole groups measures 12.6(6)°. In the absence of expected hydrogen bonding interactions, the crystal packing is influenced by a collective action of strong intramolecular C–H···S hydrogen bond interactions, close C–H···O intramolecular contacts and O–Cg π-ring interactions. A DFT molecular orbital calculation gives support to these observations.     

Reaction of 5,5-diphenyl-2-thiohydantoin with ethyl-2,3-dibromopropionate. Crystal and molecular structure of ethyl-2-{2,3-dihydro-6,6-diphenylimidazo-[2,1-b]-thiazol-5(6H)-one} formate

The crystal and molecular structure of the title compound, obtained by intramolecularN,S-dialkylation of 5,5-diphenyl-2-thiohydantoin with ethyl-2,3-di-bromopropionate, has been determined from X-ray diffractometer data. Ethyl-2-{2,3-dihydro-6,6-diphenylimidazo-[2,1-b]-thiazol-5(6H)-one}formate crystallizes in space groupP2₁/c witha=12.166(4),b=10.689(2),c=15.021(6) Å,=113.63(4)°, andZ=4. The molecular structure was found with nonplanar thiazole ring. The structure was solved withR=0.051.     

Structure of 2-ethyl-8-methyl-2,8-diazaspiro[4,5]decane-1,3-dione hydrobromide (RS-86)

Crystals of the title compound, C₁₁H₁₈N₂O₂·HBr, are monoclinic, space groupP2₁, witha=7.339(3),b=13.246(7),c=7.340(4) Å,=116.94(5)°, andZ=2. The structure was solved by direct methods and refined by fullmatrix least-squares calculations to anR value of 0.046 for 1218 observed reflections. The piperidine ring, in a chair conformation, is perpendicular (90.6°) to the strictly planar pyrrolidine-2,5-dione ring. Br^– is hydrogen bonded to the positively charged piperidine N1 atom. Bond lengths and valence angles are comparable to those of various related compounds.     

Synthesis and structure of 4-R,5-R-[5-(hydroxy-diphenyl-methyl)-2, 2-dimethyl-[1,3]dioxolan-4-yl]-phenyl-methanone, a chiral ligand building block

A triphenyl analog of taddol, 4-R,5-R-[5-(hydroxy-diphenyl-methyl)-2,2-dimethyl-[1,3]dioxolan-4-yl]-phenyl-methanone, has been synthesized and structurally characterized. This molecule could act as a chiral ligand building block in the creation of tuned taddol analogs. Structural analysis of the title compound reveals that the hydroxyl group is involved in an intramolecular hydrogen bond and does not take part in any intermolecular interaction. Crystal packing is influenced by C–H O hydrogen bonding and phenyl phenyl interactions. Crystal data: Triclinic, P1 (No. 1), a = 5.9343(4) Å, b = 8.2367(17) Å, c = 10.987(2) Å, = 88.290(6), = 75.442(4), = 80.655(6), V = 512.86(15) ų, Z = 1, D _calc = 1.258 mg/m³. Final residual values were R ₁ = 0.0407 for 3022 observed data (I > 2s(I) ) and wR ₂ = 0.0941 for all 3524 unique data.     

Crystal and molecular structure of a naphthalene-tolan photoadduct: 1,8-Diphenyl-1a,2,7,7a-tetrahydro-1,2,7-metheno-1H-cyclopropa[b]naphthalene

The title compound, C₂₄H₁₈, crystallizes in the monoclinic space groupP2₁/c with cell parametersa=16.382(10),b=6.360(3),c=18.051(11) Å, =116.6(1) °,Z=4,V=1695.6 ų. The structure was solved by direct methods and refined using least-squares procedures to a finalR of 0.097 for 811 observed (I>2₁) structure magnitudes. The variables refined were the fractional coordinates of all atoms and the individual isotropic temperature factors of the nonhydrogen atoms. The highly strained molecule has single carbon-carbon bond distances of 1.47–1.59 Å, and bond angles between 59 and 136 °.     

[CaSb2(EDTA)2(H2O)8]n: synthesis, crystal structure, and thermal behavior

The synthesis and crystal structure of a new EDTA complex, [CaSb₂(EDTA)₂(H₂O)₈]_n, are reported. This compound crystallizes in the monoclinic space group P2₁/n, with a = 7.132(1) Å, b = 21.893(3) Å, c = 10.891(2) Å, = 91.15(2)°. Sb(EDTA) entities are connected through carboxylate bridges to the calcium atoms resulting in layers parallel to the (101) plane. These layers are linked through a weak Sb···O bond (3.171 Å). Pyrolysis of this complex under sulfur vapor, between 400 and 800°C, leads to a mixture of the monometallic sulfides. Pyrolysis in air above 700°C allows the easy preparation of the mixed oxide CaSb₂O₆.     

X-ray mapping in heterocyclic design: II. Diffractometric study of crystalline 2-oxo-2,3-dihydroimidazo[1,2-a]pyridine hydrochloride

The crystal structure of 2-oxo-2,3-dihydroimidazo[1,2-a]pyridine hydrochloride, C₇H₇ClN₂O, is determined by X-ray diffraction. The structure is solved by the direct method and refined by the least-squares procedure to R = 0.0408. The alternation of bond lengths in the molecule is inconsiderable, but does not disappear completely, since no aromatization occurs upon formation of the bicycle from the molecule. This structural change is apparently due to the increased conjugation of the NH group with the pyridine residue of the bicycle. One of the specific structural features of the salt is the formation of the N⁺-HïCl^? hydrogen bond (N-H, 0.792 Å; H?Cl, 2.260 Å; and N-H?Cl, 171.2°).     

Crystal and molecular structure analysis of benzamide neuroleptics and analogs (VIII):endo- andexo-2,3-dimethoxy-N-[8-(phenylmethyl)-8-azabicyclo[3.2.1]oct-2-y1]-benzamide hydrochloride: C23H28N2O3·HCl

The crystal structures ofendo- andexo-2,3-dimethoxy-N-[8(phenylmethyl)-8-azabicyclo[3.2.1]oct-2-y1]benzamide hydrochloride have been determined by single-crystal X-ray diffraction techniques, and refined by full-matrix least squares. The endo-compound crystallizes in the monoclinic space groupP2₁/n witha=12.389(2) Å,b=22.861(3) Å,c=8.019(2) Å,=93.58(2)°, andZ=4; the exo-compound crystallizes in the monoclinic space groupP2₁/a witha=26.295(12) Å,b=12.503(4) Å,c=6.667(7) Å,=97.80(6)°, andZ=4. The calculated densities are 1.22 and 1.27 g cm^–3 respectively. FinalR-factors are 0.04 for the endo and 0.05 for the exo-compound. Comparison with a very active analog, the tropapride, suggests that the lack of antipsychotic activity is due to a different orientation of the dimethoxyphenyl or carbonyl group for the exo- and endo-compound, respectively.     

Intermolecular [2+2] photocyclization of ethyl 5-oxo-1a,2,5,5a,6,6a-hexahydro-2,6-methano-2aH-indeno-[5,6-b]oxirene-2a-carboxylate

The photodimer, 7, of ethyl 5-oxo-1a,2,5,5a,6,6a-hexahydro-2,6-methano-2aH-indeno-[5,6-b]oxirene-2a-carboxylate has been isolated and structuraally characterized. Triclinic,P ^?1,a=9.7783(6),b=11.2782(7),c=11.3445(7) Å, α=105.461(9), β=113.3759(10), γ=92.9155(11)^o,V=1089.36(12) ų,R=0.049 for 3557 unique observed reflections. Two independent molecules lying on inversion centers occupy the unit cell. The influence of the orientation of the ester group on the polycyclic skeleton is discussed.     

Crystal and molecular structure of 2β,3α-di(ethoxycarbonyl)-2,3,4aα,6,7,8aα-hexahydro-p-dioxino[2,3-e]-p-dioxin (Didox), C12H18O8

Crystals of the title compound, C₁₂H₁₈O₈, are orthorhombic:P2₁2₁2₁,a = 7·260(5),b = 9·483(6),c = 20·199(6) Å,Z = 4. The structure has been solved from the Patterson synthesis, and refined to anR-factor of 8·4% by full-matrix least-squares methods. The 6-membered rings are each in thechair conformation and arecis-fused at the 4a, 8a ring-junction. The structure led to an explanation of an unusually large chemical shift in the nmr signal from one of the methylenic hydrogen atoms on C(7).     

Crystal structure of 2-N,N-diethylamino-1-carbomethoxy-2a,8a-dihydro-2a-methoxycyclobuta [b]naphthalene-3,8-dione,C19H21NO5

Crystals of the title compound, C₁₉H₂₁NO₅, are monoclinic, space groupP2₁/c,a = 7·706,b = 14·470,c = 16·836 Å, = 106·45°,Z = 4. The structure was determined with CuK diffractometer data by symbolic addition procedures and Fourier syntheses, and was refined by full-matrix least-squares methods toR = 0·079 for 2192 observed reflexions. All non-methyl hydrogen atom positions were determined. The non-aromatic six-membered ring has aboat conformation. The four-membered ring, which iscis-fused to the six-membered ring, is slightly folded, and the planar amino and carboxyl groups lie almost in the four-membered ring plane. This geometry, and the detailed bond distances suggest electron delocalization, which may make the compound a useful intermediate in the synthesis of a stable cyclobutadiene system.We thank Dr M. E. Kuehne for suggesting the problem and for crystals, the National Research Council of Canada for financial support, and the University of British Columbia Computing Centre for assistance.     

New sulfur derivatives of 2,3-dichloropyrrolo[1,2-a] benzimidazol-1-one. Demonstration of regioselective thiolate addition and X-ray diffraction structures of 2-chloro-3-methylthiopyrrolo[1,2-a]benzimidazol-1-one and 2,3-di(benzylthio)pyrrolo[1,2-a]benzimidazol-1-one

The reaction of thiols with the heterocyclic compound 2,3-dichloropyrrolo[1,2-a] benzimidazol-1-one (1) has been investigated as a route to new redox-active, bidentate sulfur ligands. Treatment of 1 with either methylthiol or benzylthiol in the presence of pyridine affords monosulfide compounds 2-chloro-3-methylthiopyrrolo[1,2-a] benzimidazol-1-one (2) and 2-chloro-3-benzylthiopyrrolo[1,2-a]benzimidazol-1-one (3) and the disulfide derivatives 2,3-di(methylthio)pyrrolo[1,2-a]benzimidazol-1-one (4) and 2,3-di(benzylthio)pyrrolo[1,2-a]benzimidazol-1-one (5). The substitution of the first chlorine group in 2,3-dichloropyrrolo[1,2-a]benzimidazol-1-one (1) occurs regioselectively at C-3 to produce 2-chloro-3-methylthiopyrrolo[1,2-a]benzimidazol-1-one (2) and 2-chloro-3-benzylthiopyrrolo[1,2-a]benzimidazol-1-one (3), followed by replacement of the remaining chlorine group to furnish the disulfide compounds 4 and 5. The new thiols have been isolated by column chromatography and characterized in solution by spectroscopic methods. The molecular structures of 2-chloro-3-methylthiopyrrolo[1,2-a]benzimidazol-1-one and 2,3-di(benzylthio)pyrrolo[1,2-a]benzimidazol-1-one have been determined by X-ray crystallography. Compound 2 crystallizes as two independent molecules in the monoclinic space group P2₁/c, a = 13.221(2) Å, b = 18.478(2) Å, c = 8.948(1) Å, = 100.088(3)°, V = 2152.3(5) ų, Z = 8, and d_calc = 1.547 Mg/m³; R = 0.0354, R_w = 0.0739 for 2820 reflections with I > 2(I). Compound 5 crystallizes in the triclinic space group P-1, a = 5.180(1) Å, b = 11.494(2) Å, c = 17.243(3) Å, = 86.024(3)°, = 88.606(4)°, = 81.235(3)°, V = 1012.1(4) ų, Z = 2, and d_calc = 1.360 Mg/m³; R = 0.0354, R_w = 0.0692 for 2655 reflections with I > 2(I). The redox properties of the disulfide compounds 4 and 5 have been explored by cyclic voltammetry, where a one-electron reduction at ca. –1.10 V has been observed for each compound. The site of electron accession in has been established by carrying out molecular orbital calculations at the extended Hüuckel level on the model compound 2,3-di(thio)pyrrolo[1,2-a]benzimidazol-1-one.     

Crystal and molecular structure of 3a,6a-dihydro-3-phenylthiolan [2,3-d]isoxazole-4-oxide,C11H11NO2S

The crystal and molecular structure of the title compound, C₁₁H₁₁NO₂S, has been determined by X-ray analysis from diffractometric data. The crystals are monoclinic:P2₁/n, a=17.186(4),b=10.848(2),c=5.588(1) Å,=91.96(1)°,Z=4. The structure was solved by direct methods, and refined by full-matrix least-squares toR=0.043 for 1551 observed reflections. Bond lengths and angles have normal values. The isoxazoline and the thiolane rings are in an intermediate envelope/twist conformation, with a dihedral angle of 109.7(1)° between their best planes, whereas the phenyl ring is rotated 4.1(1)° from the isoxazoline ring, thus allowing extensive conjugation within this moiety.     

Crystal structure of a cyclobutane derivative: 4,8-dibromo-3,7-diketo-3, 4,4a,4b,7,8,8a,8b-octahydrodibenzo- [a,g] -biphenylene

The crystal structure of a cyclobutane derivative, 4,8-dibromo-3,7-diketo-3,4,4a,4b,7,8,8a,8b-octahydrodibenzo-[a,g]-biphenylene (C₂₀H₁₄O₂Br₂), has been determined from 1614 intensities collected with a four-circle diffractometer and refined by three-dimensional least-squares techniques. The crystals are monoclinic, space groupP2₁/c, with four molecules in a unit cell of dimensionsa = 10·863 ± 0·006,b = 21·060 ± 0·011,c = 7·772 ± 0·005 Å and β = 105·33 ± 0·04 °. The cyclobutane ring was found to have a bent configuration with a dihedral angle of 157 °.