共查询到20条相似文献,搜索用时 109 毫秒
1.
A. Auhmani E. Kossareva H. El Jamili M. Réglier M. Pierrot A. Benharref 《Journal of chemical crystallography》2000,30(8):525-530
We report here the reactivity of 6,7-epoxyhimachal-2-ene with dibromocarbene generated in situ by phase-transfer catalysis. The stereochemistry of products resulting from dibromocyclopropanation has been established by X-ray crystallography. Compound 3 is orthorhombic P212121 with a = 7.549 (1), b = 8.432 (1), c = 24.469 (1) Å, V = 1559.8 (5) Å3, Z = 4 and compound 5 is monoclinic P21 with a = 8.779 (1), b = 15.684 (1), c = 12.111 (1) Å, = 91.869 (1)°, V = 1666.7 (4) Å3 and Z = 4. 相似文献
2.
Vivek K. Gupta Madhvi M. Lal Naresh K. Satti Prabhu Dutt Punita Sharma Musarat Amina Krishan A. Suri 《Journal of chemical crystallography》2011,41(7):1064-1070
Abstract
(5R,6S,7S,8S,9S,10R,13S,14S,17S,20R,22R)-6α,7α-epoxy-5α,17α,27-trihydroxy-1-oxo-22R-witha-2,24-dienolide has been isolated from Withania somnifera leaves. Three-dimensional X-ray intensity data were collected at 293 K on Bruker CCD area-detector diffractometer equipped with graphite-monochromated MoKα radiation (λ = 0.71073 ?). The compound crystallizes in monoclinic space group P21 with unit cell parameters: a = 6.4540(2), b = 11.3656(4), c = 17.4982(5) ?, β = 90.730 o(2), Z = 2. The crystal structure was refined to a final R-value of 0.0419 for 6122 observed reflections. One water solvent molecule was observed. All the rings of the steroid skeleton are trans connected. Rings A and B exists in a half-chair conformation, ring C a chair, and five membered ring D is intermediate between half-chair and envelope. The δ-lactone ring E adopts a distorted sofa conformation. The characteristic pattern observed in the packing diagram is the appearance of twisted chains of molecules. The packing of the molecules in the crystal is stabilized by intra- and intermolecular O–H···O and C–H···O interactions. 相似文献3.
Qian Yang Bing-Yu Zhang Wei-Dong Ye Jian-Yong Yuan Duan-Jun Xu Jing-Jing Nie 《Journal of chemical crystallography》2008,38(9):659-661
Abstract The title compound (common name eplerenone), C24H30O6, is an aldosterone receptor antagonist. From the isopropyl acetate solution the compound crystallizes in monoclinic space
group P 21 with a = 8.811(1) ?, b = 11.250(1) ?, c = 11.079(1) ?, β = 93.822(12)°, Z = 2. The molecule contains three six membered rings, two five membered rings and one three membered ring. Both five membered
rings display envelope conformation, whereas three six membered rings show different conformation: chair, half-chair and envelope.
In the crystal the eplerenone molecules link to one another via intermolecular weak C–H···O hydrogen bonding to form the smaller
cavity of 12.0(1) ?3 between eplerenone molecules, no solvent molecule filled in this cavity.
Index Abstract In the title molecule three six-membered rings show different conformation. Weak C–H···O hydrogen bonding links adjacent molecules
to form the small cavity 12.0(1) ?3, no solvent molecule filled in the cavity.
相似文献
4.
Angel Dago Morales Héctor Novoa de Armas Norbert M. Blaton Oswald M. Peeters Camiel J. De Ranter Martín-Iglesias Arteaga 《Journal of chemical crystallography》2000,30(11):693-697
The compound (25R)-2,3-epoxy-5-spirostan-6,23-dione, crystallizes as a hemi-ethyl acetate solvate, having two host molecules of similar conformation per molecule of ethyl acetate, in the asymmetric unit. The O atom of the epoxy group is -oriented. The presence of the epoxy group disturbs the chair conformation in the ring A of the steroidal nucleus. Ring A has a C5,C10 half-chair conformation. The six-membered rings B, C, and F have chair conformation as expected. The D ring adopts a C14-envelope conformation and the E ring is midway between a C22,O3 half-chair and a C22-envelope conformations. The A/B, B/C, and C/D ring junctions are trans. Crystal data: C27H38O5·1/2C4H8O2, Monoclinic, space group P21, a = 7.7363(18) b = 28.769(12) c = 12.038(6) Å, = 90.88(5), V = 2679.0(10) Å3, Z = 4. The packing of the molecules is assumed to be dictated by van der Waals interactions and by intermolecular C—H ··· O hydrogen bonds. 相似文献
5.
C15H18O4 is monoclinic,P21. Unit-cell dimensions at 293 K area=15.048(5),b=9.756(3),c=15.815(5)Å,=114.18(2)°,V=2118(1)Å3,D
x=1.23 g cm–3, andZ=6. The structure has been determined from single-crystal data collected with a four-circle diffractometer and refined from 2816 observed reflections toR=0.054. The structural features determined from chemical and spectroscopic studies are confirmed and extended. The incomptine B occurs as three independent molecules with different conformations. The stereochemistry at C(6), C(7), and C(8) is 6S, 7R, and 8R. The 10-membered ring has an approximate C2 symmetry for the A, B, and C molecules. The -methylene -lactone ring adopts a half-chair conformation for molecule A, and a conformation intermediate between-envelope and half-chair for the B and C molecules, respectively. The structures are stabilized by a three-dimensional network of O-HO hydrogen bonds and several C-HO interactions. 相似文献
6.
Anna E. Kozioł 《Journal of chemical crystallography》1992,22(4):449-459
The crystal and molecular structures of mono- and di-quaternary salts ofa-isosparteine have been determined by X-ray analysis. Both N(1)-methyl--isosparteine iodide and 1,16-endomethylene-isosparteine diiodide crystallize in the space groupC2221. The N-methylation does not change the configuration of parenttrans-cisoid-trans--isosparteine. The crystallographic twofold symmetry axis coincides with molecular symmetry of the diquaternary cation. Thetrans-cisoid-trans-1,16-endomethylene--isosparteine diiodide and its stereoisomer,trans-cisoid-cis-1,16-endo-methylenesparteine diiodide, form isomorphous crystals. Short cation-anion contacts in crystal structures suggest existence of C-H--I– hydrogen bonds in the solid state. In the N(1)-methyl--isosparteine iodide crystal, 7CI– distances in the range 3.85-4.15 Å have been found, while 17 distances of this type have been observed in 1,16-endomethylene--isosparteine diiodide. 相似文献
7.
乙酰基二茂铁与三甲基氰硅烷在CH2Cl2中ZnI2催化下加成,得到产率较高的α-氰基-α-二茂铁基乙氧三甲硅烷,用元素分析、IR和1H NMR进行了表征.经X射线单晶衍射法测试表明,该化合物属正交晶系,Pbca空间群,晶胞内分子数为8,化合物分子式为C16H21FeNOSi,Mr=327.28,a=1.1995(4)nm,b=1.2441(4)m,c=2.2183(7)nm,β=90°,V=3.3103(18)nm3,Dcale=1.313g·cm-3,Z=8,最终偏离因子R=0.0456,ωR=0.0880.分析其结构表明,该化合物含有一个二茂铁基和氰基乙氧三甲基硅烷基,与二茂铁基相连的碳原子是手性原子,分子中存在超共轭效应. 相似文献
8.
Philip J. Cox David G. Durham Xiaojun Liu R. Michael E. Richards 《Journal of chemical crystallography》1993,23(10):779-783
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. 相似文献
9.
M. Sakhawat Hussain Mazhar-ul-Haque Sk. A. Ali 《Journal of chemical crystallography》1999,29(1):33-38
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 = 1402.4Å3. 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. 相似文献
10.
Derek H. R. Barton Bin Hu Joseph H. Reibenspies 《Journal of chemical crystallography》1998,28(3):239-241
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)Å3, Z = 4. 相似文献
11.
Janina Karolak-Wojciechowska Witold Kwiatkowski Stanislaw Wojciech Markowicz 《Journal of chemical crystallography》1989,19(5):893-903
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. 相似文献
12.
Abstract
The X-ray structures of two α-substituted α-(2-pyridyl-N-oxide)ethanols, the α-phenyl- (3a) and α-trifluoromethyl- (3b) derivatives, were determined. On dehydration of 3a, compound 4a was obtained. This study brought a clear proof that the α-(2-pyridyl-N-oxide)ethanols are formed following oxidation with peroxides of their corresponding pyridines. A different molecular packing was observed for the α-trifluoromethyl derivative due to an additional hydrogen bonding. Compound 3a crystallized in the monoclinic space group P 21/n with unit cell parameters a = 5.7416(1) ?, b = 14.3841(4) ?, c = 13.2821(3) ?, β = 94.918(2)°, V = 1092.90(4) ?3, Z = 4, D = 1.308 Mg/m3. Compound 3b crystallized in the triclinic space group P −1 with unit cell parameters a = 6.1209(2) ?, b = 8.1938(4) ?, c = 9.4675(4) ?, α = 73.363(3)°, β = 73.166(3)°, γ = 71.659(3)°, V = 421.32(3) ?3, Z = 2, D = 1.633 Mg/m3. Compound 4a crystallized in the monoclinic space group P 21/n with unit cell parameters a = 9.3579(3) ?, b = 12.7340(3) ?, c = 9.8579(3) ?, β = 117.3249(15)°, V = 1043.63(5) ?3, Z = 4, D = 1.255 Mg/m3. 相似文献13.
erajni-kant-verma@hotmail.com Rajnikant V. K. Gupta Jamal Firoz Shafiullah R. Gupta 《Crystallography Reports》2000,45(5):785-788
The crystal and molecular structure of the steroid 5α-cholest-6-one has been determined by X-ray diffraction analysis. The compound crystallizes in space group P21 with the unit cell parameters a = 10.575(1) Å, b = 7.698(1) Å, c = 15.284(2) Å, β= 99.34(1)°, V = 1227.72 Å3, Z = 2, and R = 0.054 for 1634 observed reflections. The six-membered rings (A, B, and C) have the chair conformations, whereas the five-membered ring Dis intermediate between 13β-envelope and 13β-14α half-chair. All the rings of the steroid skeleton are trans connected. The molecules are linked together by the intermolecular C-H?O hydrogen bonds. 相似文献
14.
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.
相似文献
15.
水热法合成α-Al2O3晶体 总被引:14,自引:9,他引:5
本文研究了不同矿化剂,不同温度对水热条件下合成α-Al2O3晶体的大小、形貌和晶体质量的影响.发现在矿化剂浓度为0.1M KOH和1M KBr条件下,填充度为35;,温度为380℃时Al(OH)3只转化成薄水铝石,无α-Al2O3晶体生成;388℃时只是部分转化成α-Al2O3;在395℃以上时完全能转化成α-Al2O3,晶体形状为六棱柱形.在矿化剂浓度为1M KOH时,填充度35;,温度为380℃时,即有部分Al(OH)3转化成α-Al2O3,390℃以上完全转化成α-Al2O3,晶面主要显露菱面. 相似文献
16.
The crystal and molecular structure of 17-hydroxy-17-5-androstano [2,3-C] Furazan, Furazabol (C20H24N2O2), has been determined by direct methods and refined by full matrix least squares to a final R of 0.0528 for 1927 observed reflections and 216 parameters, CuK, = 1.54178 Å. The compound crystallizes with two molecules in the asymmetric unit, Z = 4, Dc = 1.131 Mg m–3 space group P21, with unit cell parameters a = 18.747(3), b = 6.346(5), c = 15.647(4) Å, = 99.96(2)°, V = 1833.9 Å3, (CuK) = 0.584 mm–1. Whilst the two independent molecules have similar overall geometry there are small differences in bond lengths, bond angles and torsion angles in rings A and D and significant conformational differences in ring A. The A ring adopts a half-chair conformation in molecule A and an intermediate between a half-chair and a sofa in molecule B. The D ring in molecule A has a 13/14 half-chair conformation and in molecule B a conformation between an envelope and half-chair. 相似文献
17.
John R. Peterson Shahla Peterson John K. Baker Robin D. Rogers 《Journal of chemical crystallography》1990,20(4):327-333
The title compound, C20H14O8, Mr=382.3, crystallized from chloroform in the centric space group P¯1 witha=6.516(4),b=6.798(3),c=9.545(7) Å,=85.31(5),=73.87(5), =79.59(4)°,V=399.2 Å3, and Dcalc=1.59 g cm–3 forZ=1. Least-squares refinement of 1035 observed [Fo5(Fo)] reflections led to the final agreement index ofR=0.074. The molecule resides on a crystallographic center of inversion and is disordered into two different conformations. This manifests itself as a 50/50 disorder at O(4), C(2), and C(3). The observed structure reveals acis relationship between the bridgehead hydrogen atoms and the aryl rings. The 90 MHz1H nmr spectrum of the title compound exhibits an AAXX spin system with a H(1)C(2) to H(1)C(3) and H(1)C(2) to H(1)C(3) coupling constant of 2.8 Hz. Computer spectral simulation and Karplus equation analysis are utilized to illustrate a relaxation of the torsion angles between H(1)C(2) and H(1)C(3), and H(1)C(2) and H(1)C(3) is solution. 相似文献
18.
P. Gluziński J. W. Krajewski W. M. Daniewski M. Gumułka K. Ptaszyńska 《Journal of chemical crystallography》1992,22(5):547-550
The structure of the title compound has been investigated in the solid state by X-ray diffraction. The crystals are tetragonal, space groupP4121,2 (No. 92), with cell dimensions:a=10.463(1),c=34.603(8)Å. The structure was solved by direct methods and refined with 3634 unique reflections by a full-matrix, least-squares procedure givingR=0.0460,R
w=0.0472 (w=1/
F
2
. The stereochemical analysis of the molecule confirmed the expectations based on earlier NMR investigations of the title compound and its precursors. 相似文献
19.
采用固-液两相混合,使Nd2o3、Y2O3和V2O5在近常温条件下初步合成Nd:YVO4多晶原料,降低固相合成反应温度,减少V2O5在多晶原料制备过程中的挥发。讨论了α方向V单晶生长条件,采用提拉法,以(100)方向进行单晶生长,得到一系列掺杂浓度的Nd:YVO4单晶。 相似文献
20.
Vivek K. Gupta Shaveta Mahajan Naresh K. Satti Krishan A. Suri G. N. Qazi 《Journal of chemical crystallography》2008,38(10):769-773
Abstract (20R,22R)-6α,7α-Epoxy-5α,27-dihydroxy-1-oxowitha-2,24-dienolide (27-hydroxy-withanolide B) was isolated from Withania somnifera. The structure of the withanolide was established by spectral analysis and X-ray diffraction studies. The compound crystallizes
in the orthorhombic space group P212121 with unit cell parameters: a = 9.2163(3), b = 11.1828(4), c = 23.6146(9) ?, Z = 4. The crystal structure was refined to R = 0.0495 for 3,284 observed reflections. All the rings of the steroid skeleton are trans connected. Rings A and B exist in
a half-chair conformation, ring C a chair, and five membered ring D is intermediate between a half-chair and an envelope.
The δ-lactone ring E adopts a distorted sofa conformation. The twist along the length of the steroid nucleus is −6.5°. The
characteristic pattern observed in the packing diagram is the appearance of twisted chains of molecules packed together to
form layers.
Index Abstract Isolation and crystal structure analysis of (20R,22R)-6α,7α-epoxy-5α,27-dihydroxy-1-oxowitha-2,24-dienolide.
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