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.     

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.     

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.     

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.     

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.     

(20R,22R)-6α,7α-Epoxy-5α,27-dihydroxy-1-oxowitha-2,24-dienolide in Leaves of Withania somnifera: Isolation and its Crystal Structure

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.      

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)°.     

Anticancer agent development. 5. X-ray structure and1H nmr spectral analysis of (1α,2α,5α,6α)-2,6-bis(3,4-methylenedioxyphenyl)-3,7-dioxabicyclo[3.3.0]octane-4,8-dione

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 ų, and D_calc=1.59 g cm^–3 forZ=1. Least-squares refinement of 1035 observed [F_o5(F_o)] 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.     

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.     

Crystal Structure of 9α,11-Epoxy-7α-(methoxycarbonyl)-3-oxo-17α-pregn-4-ene-21,17-carbolactone

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.      

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.     

Crystal structure of (4α,4aα,8aα)-(±)-octahydro-2-(phenylmethyl)-2H-1,2-benzoxazin-4-ol, 4-methylbenzenesulfonate(ester)

The title compound, a bicyclic tetrahydro-1,2-oxazine, crystallizes in a monoclinic lattice, space group P2₁/c, with a = 12.9809(18)Å, b = 12.920(2)Å, c = 13.631(2)Å, = 110.713(12)°, and Z = 4. The structure found in the solid state for this conformationally mobile molecule shows the tosyl group in an axial position and a benzyl group in an equatorial position of the bicyclic system.     

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.     

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 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.     

α-Li3InF6, a ternary fluoride with a new structure type

Reaction of anhydrous binary fluorides LiF and InF₃ in sealed platinum tube at the temperature gradient 680/670°C yields α-Li₃InF₆. This low-temperature form crystallizes in the space group P2₁/m with the cell dimensions a = 4.797(3) Å, b = 8.679(1) Å, c = 10.366(1) Å and β = 90.90(1)°. The framework is built from InF₆ and LiF₆ octahedra, beside [Li₂F₆] bitetrahedra. The b-axis seems to be the backbone in the structural features. Running along it, zigzag anionic chains , resulting from one—edge shared [Li₂F₁₀] groups and double files of single InF₆ octahedra sharing common corners with [Li₂F₆], create an approximately hexagonally packed framework in the plane (1 0 0). The antiferroelectric behaviour evident from dielectric studies is confirmed by the antiparallel displacements of In and Li atoms from octahedral centres. This structure is mainly featured by the disorder observed in the lightest atoms. These atoms, which exhibit two kinds of environments, have been refined as two partially occupied sites for the tetrahedral one. Within the Li₃MF₆ compounds (M: trivalent or 3d element), this new structure reveals unexpected structural features, inducing its ferroic properties.     

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,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.     

Novel manganese(III) oxidation chemistry: X-ray crystal structures of (1α,2α,4β)-1,2-diacetoxy-4-(4-methoxyphenyl)-6-methoxy-1,2,3,4-tetrahydronaphthalene (compound A) and (1α,2α,4β)-1,2-diacetoxy-4-(2-methoxyphenyl)-8-methoxy-1,2,3,4-tetrahydronaphthalene (compound B)

CompoundA is (1,2,4)-1,2-diacetoxy-4-(4-methoxyphenyl)-6-methoxy-l,2,3,4-tetrahydronaphthalene, C₂₂H₂₄O₆,M _r=384.43, monoclinic, P2₁/n, witha=11.074(3),b=10.353(4),c=17.616(4)Å,=94.96(2)°,V=2012.1ų,D _calc=1.27 g cm^–3 and=0.55 cm^–1 forZ=4. Least-squares refinement of 1371 observed [F ₀5 (F ⁰)] reflections led to the final agreement index ofR=0.052. A twofold disorder was observed for the 1-acetoxy group whereas the 2-acetoxy group was ordered. CompoundB, (1,2,4)-1,2-diacetoxy-4-(2-methoxyphenyl)-8-methoxy-l,2,3,4-tetrahydronaphthalene, C₂₂H₂₄O₆,M _r=384.43, crystallizes in the monoclinic space group, P2₁/c, witha=16.209(2),b=10.076(1),c=13.357(4)Å,=111.41(2)°,V=2030.9ų,D _calc=1.26 g cm^–3 and=0.54 cm^–1 forZ=4. A final agreement index ofR=0.045 was realized by least-squares refinement of 1486 observed [F _o5 (F _o)] reflections. Intermolecular interactions in the cell lattices of compoundsA andB are noted. The title compoundsA andB were prepared by manganese(III) acetate oxidative dimerization of two molecules of 4-methoxystyrene and 2-methoxystyrene, respectively.