Structure of 3α,12β-dihydroxy-2β-morpholino-5α-pregnan-20-one,C25H41O4N

The crystal and molecular structure of 3,12-dihydroxy-2-morpholino-5-pregnan-20-one, C₂₅H₄₁O₄N, has been determined:M _r =419.6,P2₁,a=13.5778(8),b=14.4340(8),c=5.8943(5) Å,=94.32(1)°,V _c =1151.9(3) ų,Z=2,D _x =1.21 g cm^–3, (CuK) = 1.5418 Å, =5.6 cm^–1,F(000)=460,R=0.039,R _w =0.040 for 2421 unique observed reflections. All six-membered rings have chair conformations, and theD ring has a 13-envelope conformation. The progesterone side chain has an unusual conformation, and the C16-C17-C20-O20 torsion angle, which defines the conformation, is –152.6(3)°. The unusual conformation seems to be forced by the intramolecular hydrogen bond between the hydroxyl group at C12 and the O20 atom from the side-chain.     

Reactivity of 6α,7α-epoxyhimachal-2-ene and crystal structures of 2α,3α-dibromocyclopropanehimachal-5,7-diene and 2α,3α-dibromocyclopropane-6α,7α-epoxyhimachalane

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) ų, 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) ų and Z = 4.     

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.     

Structure of (1αH,6βH,7αH,8αH)-1α,10α-epoxy-8β-hydroxy-germacr-2,11(13)-dien-6,12-olide (Incomptine B): A sesquiterpenoid lactone

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)ų,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.     

Structures of 8α-(2′-methylbutyryloxy)-9α-hydroxymontahibisciolide,a new skeletal type of sesquiterpene lactone,and of its precursor 8α-isobutyryloxy-9-oxo-germacra-4E, 1(10)Z-dien-6β,12-olide

The structures of a new skeletal type of sesquiterpene lactone, containing a seven, five, fivering system, and of its putative precursor, a 9-oxo-melampolide, have been confirmed by single crystal X-ray structure determination. The central 5-membered ring of the new skeleton istrans-fused to the cycloheptene ring andcis-fused to the lactone ring. Transannular interactions and the geometry of thetrans carbon-carbon double bond of the oxo-melampolide and the keto-group at C9, suggest that the new seven, five, five tricyclic skeleton-type of montahibisciolide can easily be reached by a transannular cyclization process. The isobutyrloxy group of the oxo-melampolide is disordered into two partially populated conformations. 8-(2-Methylbutyryloxy)-9-hydroxymontahibisciolide,3, C₂₀H₂₈O₅, crystallizes in orthorhombic space groupP2₁2₁2₁ witha=8.294(2),b=9.740(2),c=22.675(1) Å,V=1832(1)ų,Z=4. The structure was refined toR=0.043 andR _w=0.048 for 2898 observed reflections with CuK radiation. 8-isobutyryloxy-9-oxo-germacra-4E, 1(10)Z-dien-6, 12-olide,4, C₁₉H₂₄O₅, crystallizes in monoclinic space groupC2 witha=32.879(7),b=5.793(2),c=9.884(4)Å, =99.01(3)°,V=1859.5(9)å³,Z=4. The structure was refined toR=0.054 andR _w=0.064 for 1010 observed reflections with MoK radiation.     

Structural investigation of compounds related to α,β-dehydroaminoacids: (E)-methyl-α-cyanocinnamate

The crystal and molecular structure of the methyl ester of-cyanocinnamic acid [(E)-methyl--cyanocinnamate] has been determined from three-dimensional X-ray data. C₁₁H₉NO₂ is monoclinic, space groupC2/c,Z=8,a=12.386(2),b=8.237(1),c=19.320(2) Å,=98.49(5)°. The He(I) and He(II) photoelectron (PE) spectra of (E)-methyl--cyanocinnamate are presented and discussed in comparison with those of previously investigated molecules, within a comprehensive investigation of the electronic structure of,-dehydroamino acid derivatives and related compounds.     

Synthesis and Crystal Structure of Benzoyloxymethyl (4α,8β,13β)-13-methyl-16-oxo-17-norkauran-18-carbonate Ester

Abstract  Isosteviol derivative: benzoyloxymethyl (4α,8β,13β)-13-methyl-16-oxo-17-norkauran-18-carbonate ester was synthesized by esterification of isosteviol with chloromethyl benzoate and its crystal structure was determined by X-ray diffraction method. The compound crystallizes in the triclinic space group P1 with unit cell parameters: a = 8.784(3) ?, b = 9.079(3) ?, c = 15.950(6) ?, α = 79.343(6)°, β = 79.061(5)°, γ = 89.849(5)°, Z= 2. The conformation of rings A and B is chair, whereas the conformation of ring C is unsymmetrical twist chair. The carbonyl group at the C20 is coplanar with the benzene ring. The fragment of the ester group occupying the pseudoaxial site of C1 position adopts a zigzag conformation. Index Abstract  Isosteviol derivative: benzoyloxymethyl (4α,8β,13β)-13-methyl-16-oxo-17-norkauran -18-carbonate ester was synthesized and its crystal structure was determined by X-ray diffraction method.      

Structure of 9α, 11β-dichloro-4-pregnene-3,20-dione,C21H28O2Cl2

The crystal and molecular structure of 9, 11-dichloro-4-pregnene-3,20-dione, C₂₁H₂₈O₂C1₂, has been determined:M _r =383.4,P3₁,a=7.358(2),c=30.137(20) Å,V _c =1413(2)ų,Z=3,D _x =1.35 g cm^–3, (MoK)=0.71073Å,=3.6 cm^–1,F(000)=612,T80K,R=0.060,R _w =0.052 for 2376 unique observed reflections. The steroid skeleton exhibits a flattening of theA ring relative to the rest of the molecule caused by halogen substituents. The title compound has a very high relative binding affinity for the rabbit uterine progesterone receptor. The high binding affinity may result from the flattening of theA ring relative to the rest of the steroid skeleton.     

Polymorphism in Dethoxyprone,a steroidal anesthetic. II. Crystal and molecular structure of 11α-dimethylamino-2β-ethoxy-3α-hydroxy-5α-pregnan-20-one (Dethoxyprone,form II)

The crystal and molecular structure of 11-dimethylamino-2-ethoxy-3-hydroxy-5-pregnan-20-one (Dethoxyprone, formII) (C₂₅H₄₃NO₃) has been determined by direct methods, and refined to a finalR of 0.067 for 4508 observed reflections. The compound crystallizes in space groupP2₁2₁2₁ with cell dimensionsa=10.830 (2),b=12.703 (2),c=17.490 (1) Å;Z=4,D _x =1.12 g cm^–3, (CuK )=5.28 cm^–1. The rings of the steroid skeleton are trans connected. Rings A, B, and C have chair conformations, while ring D has a half-chair conformation. The molecules are hydrogen bonded in a head to tail fashion through the hydroxy and keto groups.     

Structure of 6α-methyl-17α-hydroxyprogesterone butanoate,C26H38O4

The title compound crystallizes in space groupP2₁2₁2₁ with lattice constantsa=16.253(3),b=17.107(3), andc=8.486(2) Å. The A ring has 1,2-half-chair conformation. The calculated steric energy of a 6-methyl-17-ester progesterone molecule is lower by about 4 kJ/mol for the normal A-ring conformation. The progesterone side chain has typical conformation for 17-ester steroids; the C(16)-C(17)-C(20)-O(20) torsion angle is –24.9(4)°.     

Crystal structure of a (25R)-2α,3α-epoxy-5α-spirostan-6, 23-dione hemi-ethyl acetate solvate

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) ų, 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.     

Crystal structure of methyl-3, 4-O-ethylidene-β-L- arabinopyranoside

The acid-catalyzed ethylidenation of several methyl pentopyranosides has been studied and syntheses of many cyclic alkyl orthoacetates from pentopyranosides have been reported. In a study of the scope and limitation of the reduction of sugar epoxides with diborane/sodium borohydride, methyl-4-O-acetyl-2,3-anhydro--L-lyxopyranoside was reduced, yielding two products: methyl-2,3-anhydro--L-lyxopyranoside and methyl-3,4-O-ethylidene--L-arabinopyranoside. The latter product was characterized by X-ray diffraction and its structure indicates that the epoxide was not reduced as expected; rather, the epoxide was opened by the hydroxyl group of the reduced acetyl. Crystals of the title compound are monoclinic, space group P2₁ with the following cell dimensions: a = 5.818(l) Å, b = 10.842(2) Å, c =7.251(1) Å, = 91.47(1)°, Z = 2. Complete three-dimensional data (2_max = 150° for Cu K) were collected on a CAD-4 diffractometer by the –2 scan method. The structure was solved by the application of direct methods and refined by full-matrix least-square methods to a final reliability index of 0.04 for the observed 1031 reflections (I 3). The ethylidene ring has a twist conformation with a torsion angle of –42.8° about the C4–O bond. The pyranose ring is in a flattened chair conformation with the C2–C3–C4–C5 torsion angle of 33.5°. Of the acetal bond lengths, the C5–O5 length, (1.423 Å) is shorter than the values found in other methyl pyranosides. O2–H is involved in a bifurcated hydrogen bond intramolecularly to O1 and intermolecularly to O4.     

Isolation and Crystal Structure of 6α,7α-Epoxy-5α,17α,27-trihydroxy-1-oxo-22R-witha-2,24-dienolide monohydrate-A Withasteroid from Withania somnifera Leaves

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.     

Crystal structure of 17β-hydroxy-17α-methyl-5α-androstano [2,3-C] Furazan (Furazabol)

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 ų, (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.     

The Synthesis and Crystal Structure of (4α,8β,13β,16β)-13-Methyl-16,18-diol-17-Norkaurane: A Simultaneous Reduction Product of Isosteviol

Abstract  

(4α,8β,13β,16β)-13-methyl-16,18-diol-17-norkaurane was synthesized by esterification and reduction of isosteviol, respectively. The structure of the title compound was established by spectral analysis and X-ray diffraction studies. The compound crystallizes in the orthorhombic space group P2₁2₁2₁ with unit cell parameters: a = 7.3705 (14) ?, b = 13.508 (3) ?, c = 20.139 (4) ?, V = 2005.1 (7) ?³, Z = 4. The conformation of rings A and B is chair, whereas the conformation of ring C is unsymmetrical distorted chair. The stereochemistry of the A/B and B/C ring junctions is trans, while the five-membered ring D adopts an envelope conformation.     

Structure of 11α-hydroxy-progesterone,C21H30O3

The structure of the title compound, C₂₁H₃₀O₃, was determined by X-rays.M _r =330.5, orthorhombic,P2₁2₁2₁,a=8.4451(9),b=10.7074(8),c=20.1525(40) Å,V=1822(8) ų,Z=4,D _x =1.205 mg m^–3. CuK radiation (1.54184 Å),(CuK)=5.85 cm^–1,F(000)=720. FinalR=0.054R _w =0.049 for 1774 unique reflections. The structure was solved usingMultan. TheA ring adopts an intermediate sofa-half-chair conformation and is bent toward the face of the steroid skeleton. RingsB andC have typical chair conformations, and theD ring has a slightly distorted half-chair conformation. The progesterone side chain has a typical conformation, and the C16-C17-C20-O20 torsion angle is –17.9°. An intermolecular hydrogen bond is formed between the hydroxyl group and the progesterone side chain.     

Crystal and molecular structure of 7α, 8α, 13-trihydroxy-marasman-5-oic acid γ-lactone,C15H22O4

The structure of the title compound has been investigated by X-ray diffraction methods. The crystals are monoclinic, space groupP2₁, with cell dimensions:a=9.802(3),b=6.192(1),c=12.392(2) Å, and=112.40(2)°. The structure was solved by direct methods, and refined with 1492 unique reflections by a full-matrix, least-squares procedure givingR=0.0450. Thetrans arrangement of H-8 and H-9 hydrogens as deduced from earlier¹H NMR experiments was fully confirmed by the X-ray investigations.     

Synthesis,NMR, and X-ray crystallographic determination of the absolute configuration of 4,6-O-ethylidene-2,3-di-O-methanesulfonyl-α-d-glucopyranosyl chloride

The synthesis, NMR spectra and crystal structure of 4,6-O-ethylidene-2,3-di-O-methanesulfonyl--d-glucopyranosyl chloride are reported. The chloro substituted carbohydrate, C₁₀H₁₇ClO₉S₂, crystallizes in the monoclinic space group.,P2₁, witha=10.124(4),b=9.517(4),c=18.058(8) Å and =105.18(1)°. FinalR=0.0434. There are two independent molecules in the asymmetric unit with conformations that differ around the mesyl (–S(O)₂CH₃) groups.     

Structure of 6β-acetoxyprogesterone,C23H32O4

The X-ray crystal structure of 6-acetoxyprogesterone, C₂₃H₃₂O₄, has been determined. This compound crystallizes in space groupP2₁2₁2₁ witha=13.195(3),b=15.035(4),c=10.705(3) Å,V=2139.8(9) ų,M _r=372.5,Z=4,D _x=1.156g cm^–3; MoK radiation (=0.7107 Å),=0.72 cm^–1,F(000)=808;R=0.069, andR _w=0.052 for 1292 reflections. RingA adopts a normal 1,2-half-chair conformation. The side chain is typical for a 20-ketosteroid conformation.     

溶剂热法可控合成α-,β-MnS纳米材料和γ-MnS纳米线

通过调控溶剂热法的锰源、硫源、反应温度,尤其是有机添加剂的种类等反应参数,合成了具有不同结构与形貌的α-,β-MnS纳米材料和γ-MnS纳米线.采用透射电镜(TEM)和X射线衍射(XRD)研究了不同反应参数变化对产物结构与形貌的影响,着重分析了添加剂聚乙烯吡咯烷酮(PVP)、乙二胺(EDA)与纳米MnS或其生长基元的络合作用,及其对纳米MnS晶型与形貌的控制作用.提出了两种含氮活性基团有机添加剂在溶剂热合成中的作用机理.