Synthesis and structure determination of 3α-triphenylstannyl-cholest-5-ene

3-Triphenylstannylcholest-5-ene (1) has been synthesised and its molecular structure has been determined by single crystal X-ray diffraction. Refinement in the triclinic space groupP1 witha=7.805(6),b=7.862(5),c=32.351(10)Å, =90.87(8), =94.77(8) and =101.15(4)^o converged atR=0.063. One of the two crystallographically independent molecules in the unit cell has a patially disordered side chain. The bond lengths and valency angles about tin indicate some steric hindrance due to the proximity of one of the phenyl rings with the B ring of the steroid nucleus.     

Isolation and crystal structures of 1∶3 molecular complexes of triethylenediamineN,N′-dioxide with hydrogen peroxide and water

Two crystalline adducts have been isolated from the reaction of triethylenediamine with aqueous hydrogen peroxide and characterized by X-ray crystallography. ComplexI, ON(CH₂CH₂)₃NO·3H₂O₂, crystallizes in space groupP4₁2₁2 witha=6.772(1),c=23.664(3) Å, andZ=4. The triethylenediamineN,N-dioxide molecule occupies a site of symmetry 2, as does one of the two independent hydrogen peroxide molecules which exhibits orientational disorder. In the crystal structure, both molecular components are linked by hydrogen bonds to form a three-dimensional network. Crystals of compoundII, ON(CH₂CH₂)₃NO·3H₂O₂, belong to space groupPca2₁, witha=15.397(1),b=7.126(2),c=9.030(4) Å, andZ=4. TheN,N-dioxide and water molecules form hydrogen-bonded corrugated layers spaced between the (200) family of planes. The structures have been refined toR _F values of 0.065 (I) and 0.049 (II) using, respectively, 1171 and 747 observed MoK data.     

Molecular and crystal structures of 4-acylphenyl 4′-alkyloxybenzoates

The crystal structures of four liquid-crystal (LC) compounds belonging to 4-acylphenyl 4′-alkyloxybenzoates with the general formula C _n H_{2n + 1}-C(O)-C₆H₄-O-C(O)-C₆H₄-O-C _m H_{2m + 1} numbered as 1/6, 1/7,2/7, and 3/7 (the numbers in the code indicate the ratios of the numbers of alkyl-chain units, n/m) are determined. Compounds 1/6 and 1/7 form smectic and nematic phases, but they are monotropic mesogens, whereas compounds 2/7 and 3/7 form only an enantiotropic smectic phase. Compound 3/7 crystallizes in two crystal modifications—triclinic with Z′ = 2 (3/7 _tr ) and monoclinic with Z′ = 4 (sp. gr. P2, 3/7 _mon ). All crystals consist of alternating aromatic and aliphatic regions and are characterized by the presence of weak directional interactions, such as C-H...O hydrogen bonds and π-stacking interactions. This provides the necessary conditions for the formation of a mesophase, and the existence of two types of structure-forming units is in line with the formation of a smectic phase. An explanation is proposed for the monotropic properties of 1/6 and 1/7.     

Synthesis of spinacine and spinacine derivatives: crystal and molecular structures of Nπ-hydroxymethyl spinacine and Nα-methyl spinaceamine

The natural amino acid L-Spinacine (4,5,6,7-tetrahydro-1H-imidazo[4,5-c]pyridine-6-carboxylic acid) has been synthesized following a new pathway which gives a chemically and optically pure product with an excellent yield. The crystal structures of a synthetic intermediate, N^π-hydroxymethyl-spinacine, and a spinacine derivative, N^α-methyl-spinaceamine, have been investigated through X-ray diffraction: Spi(πMeOH)·H₂O, monoclinicP2 _i,a=8.571(1),b=6.682(1),c=8.588(1) Å, and β=94.67(1)^o. Spm(αMe)·2HCl·H₂O, triclinicP l,a=7.492(4),b=10.799(3),c=7.040(2) Å, α=91.88(2), β=98.36(3) and γ=73.34(3)^o. Spi(πMeOH) crystallizes with a water molecule and displays a zwitterionic character. The carboxylate group is in equatorial position and forms a short electrostatic interaction of 2.618(2) Å between one of its oxygens and the protonated nitrogen of the tetrahydropyridine ring. The crystal packing is assured by strong O?H???O, O?H???N, N?H???N intermolecular hydrogen bonds and C?H???O close contacts. The biprotonated compounds Spm(αMe) crystallizes with two Cl^? anions and a water molecule. The positive charge on the imidazole ring is delocalized on the conjugated moiety N=C?N. The crystal is built up by clusters formed by two biprotonated Spm(αMe) molecules, four Cl^? anions and two water molecules linked together by hydrogen bonds.     

Structure analysis of 3β-chloro-6-nitrocholest-5-ene

The crystal structure of the title compound (C₂₇H₄₄NO₂Cl) is determined by X-ray structure analysis. The compound crystallizes in the orthorhombic space group P2₁2₁2₁ with the unit cell parameters a = 7.207(1) Å, b = 11.292(1) Å, and c = 32.373(5) Å. The structure is solved by direct methods and refined to R = 0.060. Rings A and C exist in the chair conformation. Ring B adopts a half-chair conformation, and ring D is a 13β envelope. The A/B ring junction is quasi-trans, while the B/C and C/D ring systems are trans fused about the C(8)–C(9) and C(13)–C(14) bonds, respectively. Molecules are linked together by the C-H?O hydrogen bonds.     

The crystal structure of 5α,9α-peroxyergosta-7,22-dien-6-one-3β-ol acetate

Ergosterol acetate, in pyridine, reacts with hydrogen peroxide and catalytic amounts of FeCl₃ to afford the unusual product 5,9-peroxyergosta-7,22-dien-6-one-3-ol acetate. The peroxide, in the title structure, is seen to bridge the C5 and C9 positions of the sterol backbone. Crystal data: C₃₀H₄₄O₅, orthorhombic, P2₁2₁2₁, a = 6.552(2), b = 11.048(8), c = 37.60(2), V = 2772(3)ų, Z = 4.     

The crystal and molecule structure of three 2,4,6-trinitrobenzene derivatives:α,α,α-trifluoro-2,4,6-trinitrotoluene (C7H2F3N3O6), 2,4,6-trinitrobenzamide (C7H4N4O7), 2,4,6-trinitrobenzoic acid (C7H3N3O8)

The crystal and molecular structures of three 2,4,6-trinitrobenzene derivatives have been determined. Forα,α,α-trifluoro-2,4,6-trinitrotoluene (1): monoclinic,P2₁/n,a=7.510(2),b=9.273(2),c=14.984(0) Å,β=99.02(2)°,V=1028.1(4)° ų,Z=4,D=1.816 g cm^?3,R(F)=0.051, andR(wF)=0.055. For 2,4,6-trinitrobenzamide (2): orthorhombic,Pbca,a=9.248(3),b=14.377(6),c=17.729(4) Å,V=1958(1) ų,Z=8,D=1.737 g cm^?3,R(F)=0.073, andR(wF)=0.077. For 2,4,6-trinitrobenzoic acid (3): orthorhombic,P2₁2₁2₁,a=6.553(1),b=11.405(2),c=12.796(2) Å,V=956.3(3) ų,Z=4,D=1.785 g cm^?3,R(F)=0.045, andR(wF)=0.046.1 crystallizes as discrete molecules,2 as weakly hydrogen-bonded dimers and3 as a chiral polymer of hydrogen-bonded helices. In1, the presence of the nonplanar CF₃ substituent causes a large twisting of theα-nitro groups out of the plane of the benzene ring, whereas the nearly planar C(O)NH₂ and C(O)OH substituents in2 and3 are perpendicular to the benzene plane and do not cause a significant rotation of theα-nitro groups.     

The crystal and molecular structure of trans-dimethyl 2α-methyl(3αH) perhydro [1,2]oxazolo-[2,3-a]azepine-2α,3α-dicarboxylate: A 7/5-fused ring system

The title compound crystallizes in the monoclinic space group P2₁/n, with a = 6.225(1), b = 14.612 (1), c = 15.520 (1) Å, = 96.6(3)°, Z = 4 and V = 1402.4ų. The stereochemistry of the 7/5-fused ring system is trans, the 7-membered and the 5-membered rings are found to be in the chair and envelope conformations, respectively. This represents the first study of a compound containing the 7/5-ring skeleton shown in (3) below.     

Synthesis and Crystal Structure of 3-Quinuclidinyl α-(Cyclopentyl-1-ene)-α-hydroxy-α-phenylacetate

Abstract The title compound 3-quinuclidinyl α-(cyclopentyl-1-ene)-α-hydroxy-α-phenylacetate was obtained by the reaction of methyl α-(cyclopentyl-1-ene)-α-hydroxy-α-phenylacetate with 3-quinuclidinol in n-heptane. Its structure was characterized by ¹H, ¹³C NMR, MS and X-ray single-crystal diffraction techniques: C₂₀H₂₅NO₃, M _r = 327.41, orthorhombic, space group P2₁2₁2₁ with a = 8.547(2), b = 11.428(4), c = 18.288(5) ?, V = 1786.3(9) ?³, Z = 4. The title compound comprises a tertiary α-hydroxy acid and a bicyclo[2.2.2]octan moiety. The crystal structure shows the presence of the intermolecular O(1)–H(1)···N(1) hydrogen bonds. Index Abstract The title compound, 3-quinuclidinyl α-(cyclopentyl-1-ene)-α-hydroxy-α-phenylacetate was obtained by the reaction of methyl α-(cyclopentyl-1-ene)-α-hydroxy-α-phenylacetate with 3-quinuclidinol in n-heptane and its crystal structure determined. The title compound comprises a tertiary α-hydroxy acid and a bicyclo[2.2.2]octan moiety. The crystal structure shows the presence of the intermolecular O(1)–H(1)···N(1) hydrogen bonds.      

Molecular and crystal structures of a tricyclic γ-lactam ketone and its Mannich base

A tricyclic -lactam ketone, 1,10a-Dihydropyrrolo[1,2]isoquinoline-3,10(2H,5H)-dione, and its corresponding Mannich base, 10a-(Dimethylaminomethyl)-1,10a-dihydropyrrolo[1,2b]isoquinoline-3,10(2H,5H)-dione hydrochloride, have been synthesized. The molecular and crystal structures of both compounds were studied by NMR-spectroscopy and X-ray crystallography. Unit cell parameters are:a=8.799(7),b=7.137(6),c=16.156(8)Å,=76.28(5)°, space groupP2₁/c forthe first compound, anda=15.343(9),b=7.490(6),c=13.465(8) Å,=110.98(3)°, space groupP2₁/c for the second. The structures were refined to discrepancy factorsR=0.068 for 1261 andR=0.047 for 2138 observed CuK data, respectively. The conversion of the tricyclic -lactam ketone to its corresponding Mannich base does not affect thecis configuration between the fused tetrahydropyridine and -lactam rings, but does result in conformational changes in both rings.     

2α-Hydroxy-3α-[N-alkyl(aryl)]-pinanoamines. Part II. Synthesis and the nature of some pinanoamines and crystal and molecular structure of 2α-hydroxy-3α-(N-n-butyl)-pinanoamine hydrochloride

Several optically pure representatives of 2-hydroxy-3-[N-alkyl (aryl)] pinanoamines, potential chiral auxiliaries in organic synthesis, were obtained. In addition, a structural examination of 2-hydroxy-3-(N-n-butyl)-pinanoamine hydrochloride was conducted. Results of these studies confirm the structure of the amines obtained and the correctness of the proposed reaction pathway.Crystal data: C₁₂H₂₈NOCl,P2₁/c,a=13.196(1),b=8.562(1),c=14.276(1) Å,=110.41(3)°,R=0.034 for 2046 reflections.Part I,J. Cryst. Spec. Res. (1989)19, 535.     

The crystal structures of two reaction products of α-halopyruvamide with nitrogen and sulfur nucleophiles

Two compounds have been prepared during the investigation of the reactivity of -halopyruvamides. The reaction products: 3-(4-chlorophenyl)imidazo[1,2-a]pyridine-2-carboxamide (1) and 7-carbamoyl-5-phenyl-2,3-dihydro[1,3]thiazolo[4,3-b][1,3]thiazol-4-ium chloride (2) were structurally characterized by x-ray crystallography. Compound 1 crystallizes in the orthorhombic space group Pca2₁ with a = 28.813(2), b = 9.369(1), and c = 9.361(1) Å. The structure contains two crystallographically different molecules. Compound 2 crystallizes in the monoclinic space group P2₁/c with the following cell parameters: a = 8.5895(8), b = 22.499(2), c = 7.4133(6) Å, and = 110.204(1)°.     

Molecular structures of four triterpenoids. X-ray crystallographic analysis of methyl 2α,3β,23α-triacetoxy-19α-hydroxyurs-12-en-28β-oate

A triterpenoid glycoside has been isolated from the roots of a herb used in traditional Chinese medicine. The molecular structure of this compound and its derivatives have been determined by spectroscopic studies and an X-ray analysis of the 2,3,23-triacetoxy-28-methyl ester of the aglycone. This aglycone belongs to the ursene structure series. The hydroxy group on ring E of these triterpenoids is orientated and the side chains at C(2), C(3), C(4) and C(17) are .,, and orientated, respectively. The C ring, which has a double bond at C(12)=C(13), adopts a sofa conformation.     

Synthesis and crystal structure of 7-ethoxyl-4′-hydroxyisoflavone

7-Ethoxyl-4-hydroxyisoflavone was prepared and its crystal structure was examined by X-ray diffraction. Crystallization of the title compound occurs in the monoclinic, space group P2(1)/c with a = 11.144(2) Å, b = 10.209(1) Å, c = 13.191(2) Å, = 113.43(1) and Z = 4. The molecular structure of title compound consists of a benzopyranone moiety, a phenyl moiety, a hydroxyl and an ethoxyl group. The benzopyranone ring is not coplanar with the phenyl ring, the dihedral angle being 46.75. The ethoxyl group is nearly coplanar with its corresponding ring with the torsion angle 175.23(2). Three kinds of hydrogen bond and two kinds of aromatic stacking interaction link the title compounds into a three-dimensional networking structure.     

Refinement of the crystal structures of low-rare-earth and “typical” burbankites by the Rietveld method

The crystal structures of two samples of burbankite from the Khibiny massif, namely, low-rare-earth burbankite (Na_1.82Ca_1.02Y_0.02)_2.86(Sr_2.32Ba_0.43Ca_0.17La_0.06Ce_0.02)_3.00(CO₃)₅ from pectolite metasomatites and burbankite of the characteristic composition (Na_2.22Ca_0.65Y_0.03)_2.97 × × (Sr_2.10Ba_0.33Ce_0.23Ca_0.15La_0.12Nd_0.05Pr_0.02)_3.00(CO₃)₅ from alkaline hydrothermolites, were refined by the Rietveld method. The experimental data were collected on an ADP-2 diffractometer (λCuK _α radiation, Ni-filter; 15.00° < 2θ < 155.00°; 2θ scan with steps 0.02°; the exposure time per step, 15–20 s; the number of (α₁ + α₂) reflections 556–570). All the calculations were performed using the WYRIET program (version 3.3) in the sp. gr. P6₃ mc. For low-rare-earth burbankite: a = 10.5263(1) Å, c = 6.5392(1) Å, R _P = 3.52, R _wp = 4.49, R _B = 4.10, and R _F = 4.11. For burbankite from alkaline hydrothermolites: a = 10.5313(1) Å, c = 6.4829(1) Å, R _P = 2.54, R _wp = 3.23, R _B = 3.06, and R _F = 3.44. The structures were refined using the anisotropic thermal parameters of cations.     

A comparison of the crystal structures of (dabcoH2)CuCl4 and (dabcoH2)CuCl4⋅H2O

The crystal structures of the anhydrous and monohydrated (dabcoH₂)CuCl₄nH₂O salts (n = 0,1) have been determined and a comparison of their crystal structures has been reported. The anhydrous salt is monoclinic P2₁/c with a = 9.045(2) Å, b = 6.9270(10) Å, c = 18.767(4) Å and = 90.07(3)° with V = 1175.8(4) ų. The hydrated salt is also monoclinic P2₁/c with a = 9.266(2) Å, b = 9.395(2) Å, c = 14.386(3) Å and = 93.32(3)° with V = 1250.3(5) ų. The structures of the two salts are closely related. Both compounds contain isolated distorted (compressed) tetrahedral CuCl₄ ^2– anions, diprotonated dabco cations, and in the case of the hydrated salt, lattice H₂O molecules. In the anhydrous salt, each of the two N–H⁺ groups of the dabcoH₂ ²⁺ dications form bifurcated hydrogen bonds to chloride ions on adjacent CuCl₄ ^2– anions along the c axis, thus forming chains running parallel to the c axis. In the hydrated salt, a water molecule is inserted into one of the pair of bifurcated hydrogen bonds, forming instead N–H O–H CuCl₄ ^2– linkages. The chains thus formed are cross-linked by O–H Cl hydrogen bonds between the chains. Because of this additional hydrogen bonding, the CuCl₄ ^2– anions in the hydrated salt are distorted further from tetrahedral geometry.     

Metal-hydroxycarboxylate interactions: syntheses and structures of K2[VO2(C6H6O7)]2·4H2O and (NH4)2[VO2(C6H6O7)]2·2H2O

Potassium and ammonium dimeric (citrato)dioxovanadium(V) hydrate K₂[VO₂(H₂cit)]₂·4H₂O1 and (NH₄)₂[VO₂(H₂cit)]₂·2H₂O2 (H₄cit=citric acid) have been prepared and characterized by X-ray structure analyses. Vanadate1 crystallizes in the monoclinic space groupP2₁/n (No. 14) with unit cell parameters:a=9.304(2),b=11.756(2),c=11.911(2)Å, =111.72(3)°, andD _c=1.911 g/cm³,Z=2; Vanadate2 also crystallizes in the monoclinic space groupP2₁/n with unit cell parameters:a=9.719(2),b=11.111(3),c=11.294(2)Å, =109.03(2)°, andD _c=1.781 g/cm³,Z=2. Each dimer contains a centro-symmetric planar four-member V₂O₂ ring with two exocyclic citrate entities coordinated by the oxygen atoms of the hydroxy-and -carboxylate ligands, while the other two -carboxylate groups remain uncomplexed. Principal dimensions of the V–O bonds are 1.986(4)_av (hydroxy) and 1.980(3)Å(-carboxyl) for vanadate1, 1.988(2)_av (hydroxy) and 1.974(3)Å(-carboxyl) for vanadate2.     

Crystal and molecular structures of two unsaturated monosaccharides: methyl 6-(N-benzenesulfonylamino)-N,O-isopropylidene-2,3,6,8-tetradeoxy-α-D-erythrooct-2-enopyranos-4-uloside,and 1,1-O,O-ethylidene-3,4-dideoxy-D,L-hex-3-enoz-2-ulopyranos-5-ulose

Methyl 6-(N-benzenesulfonylamino)-N,O-isopropylidene-2,3,6,8-tetradeoxy--d-erythrooct-2-enopyranos-4-uloside, C₁₈H₂₃N₁O₆S₁, (3) crystallizes in the orthorhombic space groupP2₁2₁2₁. The unit cell parameters are:a=7.839(2),b=10.111(2),c=24.217(5) Å. The dihydropyranone ring adopts a deformed sofa conformation with the O5 atom deviating 0.586(2) Å from the least-squares plane and the -face of the carbonyl group shielded by the terminal (C8) methyl group. 1,1-O,O-Ethylidene-3,4-dideoxy-d,l-hex-3-enoz-2-ulopyranos-5-ulose, C₈H₁₀O₅, (6) crystallizes in the monoclinic space groupP2₁/n. The unit cell parameters are:a=6.310(1),b=18.656(3),c=7.604(1) Å, =106.01(1)°. The dihydropyranone ring adopts a deformed sofa conformation with O6 atom deviating 0.482(1) Å from the leastsquares plane and the hydroxy and dioxolanyl substituents are in pseudoaxial and pseudoequatorial positions, respectively. The average planes of six-membered and five-membered rings are approximately coplanar.     

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.