Orthorhombic Space groupP212121 Witha Research Articles

Stereochemical Study of a 13β,28-Epoxyoleanane

The stereochemistry of 3β-acetoxy-12α-bromo-13β,28-epoxyoleanan-16α-ol (2b) has been examined by n.m.r. methods and established by an X-ray crystallographic examination. Steric hindrance of the 16α-hydroxy group is shown not to be as great as previously reported. The bromo epoxide (2b), C32H51BrO4, M 579·66, crystallized in the orthorhombic space group P 212121 with a 16·118(2), b 16·615(3), c 11·024(7) Å, V 2952(1) Å3 , Dc(Z = 4) 1·304 g cm-3 , N = N(unique) = 1954, No 1731 [I > 2·5σ(I)], Nvar = 335, conventional R 0· 039, Rw 0·038.

The molecular structures of three germacrolides related to parthenolide

The germacrolide-class sesquiterpene lactone, 1,10-epoxyparthenolide, C15H20O4,1, crystallizes with two independent molecules in monoclinic space groupP21 witha=10.6845(5),b=9.0763(4),c=15.4326(7) A, β=105.887(4)°,V=1439.4(3) A3,Z=4.R=0.037 for 2425 observed data. Its 11βH, 13-dihydro-derivative 1,10-epoxydihydroparthenolide, C15H22O4,2, crystallizes in orthorhombic space groupP212121 witha=7.6414(10),b=12.559(2),c=14.6821(14) A,V=1409.0(3) A3 Z=4.R=0.031 for 1555 observed data. The corresponding unexposidized compound, 11βH,13-dihydrocostunolide, C15H22O2,3, crystallizes with three independent molecules in orthorhombic space groupP212121 witha=7.3576(5),b=23.505(3),c=24.185(2) A,V=4182(1) A3,Z=12.R=0.070 for 2767 observed data. In all, the 10-membered rings adopt approximate chair-chair conformations. In all, the double bonds or epoxidized double bonds are E, both methyl groups on the 10-ring are β, and the α-methylene-γ-lactone (or α-methyl-γ-lactone) istrans-fused at C6 and C7 with H6 β and H7 α. In the dihydro compounds, the H at C11 is β.

The molecular structures of two furanoheliangolides

The heliangolide-class sesquiterpene lactone 8β-angeloyloxy-9α-acetoxycalyculatolide, C22H26O8,1, crystallizes in orthorhombic space groupP212121 witha=12.455(3),b=12.601(3),c=14.023(5) A,V=2200(1)A,3 Z=4.R=0.059 for 1735 observed data. The 11,13-dihydro-11α, 13-epoxyatripliciolide-8β-angelate, C20H22O7. 1/2 H2O,2, crystallizes as the hemihydrate with two molecules in the asymmetric unit in triclinic space groupP1 witha=9.422(1),b=9.559(1),c=12.358(3) A, α=101.62(2)°, β=91.30(2)°, γ=117.80(1)°,V=955.6(7)A3,Z=2.R=0.046 for 3607 observed data. In both, the 10-membered rings adopt approximate chair-boat conformations. Their conformations are typical for heliangolides. The methyl group C14 is α, while the C-15 has a β-orientation. The α-methylene-γ-lactone istrans-fused at C6 and C7 with H6 β and H7 α. In compound2, the epoxide at C11–C13 has an α orientation.

Tirucallane-type triterpenoids: nmr and X-ray diffraction analyses of 24-epi-piscidinol A and piscidinol A

A new tirucallane-type triterpenoid named 24-epi-piscidinol A (1) has been isolated fromCastela texana (T. & G.) Rose (Simaroubaceae) and determined to have the structure 23R,24R,25-trihydroxytirucall-7-en-3-one by X-ray crystallographic analysis. Crystals of 24-epi-piscidinol A are monoclinic, space groupC2,a=23.84 (3),b=7.012 (7),c=17.35 (2) A, β=103.46 (2)o. Another triterpenoid piscidinol A (2), crystallizes in the orthorhombic space groupP212121 witha=10.659 (2),b=14.499 (3),c=17.922 (4) A, β=90°. Two coumarino-lignans, cleomiscosin A and C, were also obtained in the course of this work. This is the first time of isolation of tirucallane-type triterpenoids and coumarino-lignans from the genusCastela.

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. 8α-(2′-Methylbutyryloxy)-9α-hydroxymontahibisciolide,3, C20H28O5, crystallizes in orthorhombic space groupP212121 witha=8.294(2),b=9.740(2),c=22.675(1) A,V=1832(1)A3,Z=4. The structure was refined toR=0.043 andR w=0.048 for 2898 observed reflections with CuKα radiation. 8α-isobutyryloxy-9-oxo-germacra-4E, 1(10)Z-dien-6β, 12-olide,4, C19H24O5, crystallizes in monoclinic space groupC2 witha=32.879(7),b=5.793(2),c=9.884(4)A, β=99.01(3)°,V=1859.5(9)a3,Z=4. The structure was refined toR=0.054 andR w=0.064 for 1010 observed reflections with MoKα radiation.

Structure of the [5S,15S] isomer of the macrocyclic complex, [La(NCS)3(C24H30N6)

The crystal and molecular structure of the [5S,15S] isomer of the [LaL(NCS)3] complex (L=C26H30N6) was determined by single crystal X-ray diffraction analysis. The compound crystallizes in the orthorhombic space group P212121 witha=13.647(4),b=19.504(4),c=11.606(4)A. The 9-coordinate La(III) is bound to the N atoms of three monodentate isothiocyanates and to the six N atoms of the macrocycle ligand L, which has an 18-membered, six-nitrogen donor cavity and two peripheral −CH3 substituents.

Single crystal X-ray structure of 11-acetoxy-4-deoxyasbestinin B

The crystal structure of 11-acetoxy-4-deoxyasbestinin B (C22H34O4,M r=362.49) crystallized in the orthorhombic space groupP212121 witha=10.923(5)A,b=11.127(5)A,c=17.047(5)A,V=2072(3)A3,Z=4,D x=1.163g/cm−3. MoK α radiation was used for data collection at room temperature. The finalR=0.042 for 2464 observed reflections. The stereochemical assignments of the molecule from the 2-D NMR data are verified totally by the overall geometry of the molecule obtained from the X-ray diffraction analysis.

Crystal structure of a nucleoside analog: 2?,3?-dideoxy-3?-fluoro-5-bromocytidine

The title compound crystallizes in the orthorhombic space groupP212121 witha=5.084(1),b=14.322(3),c=16.065(2)A,Z=4. The structure was solved by the heavy atom method and refined by full-matrix least-squares calculations to a finalR value of 0.033 for 1106 unique observed reflections. The N-glycosidic torsion anglex has a value of −153.7(4)°, in the anti-range. The sugar pucker is2T3 withP=175(1)° andψ=30(1)°. The C4′-C5′ conformation is + sc with γ=46.7(7)°. The structure is stabilized by N-H⋯N, N-H⋯O and O-H⋯O hydrogen bonds and C-H⋯O close contacts.

Crystal structure of a nucleoside analog: 9-(R)-[6-(R)-hydroxymethyl-1-oxa-4-thiacyclohexan-2-yl] adenine

The title compound (C10H13N5O2S,Mr=267.3) crystallizes in the orthorhombic space groupP212121 witha=7.579(8),b=7.686(2) andc=20.941(4)A,V=1220(1)A3,Dx=1.456 gm cm−3,Z=4,μ=23.6 cm−1,F(000)=560 andT=293 K. The structure was solved by direct methods and refined to aR value of 0.068 for 776 unique observed reflections. The oxathiane ring adopts a chair conformation. In the crystal structure the molecules are held together by hydrogen bonds and C-H⋯O close contacts.

Structure of a Cu(II)-containing peptide, diaquo-gly-l-tyr Cu(II) dihydrate, [Cu(C11N2O4H13)(H2O)2�2H2O

The structure of the Cu(II) complex of gly-l-tyr [Cu(C11N2O4H13) (H2O)2]·2H2O has been solved by X-ray diffraction methods. The compound crystallizes in the orthorhombic space groupP212121 witha=11.970(2) A,b=12.485(2) A andc=10.418(3) A, respectively, λ(MoKα)=0.710 A,D c =1.59 Mgm−3,D m =1.59 Mgm−3, finalR=0.04. The structure was solved by heavy atom (Cu) phased Fourier and refined by full-matrix least squares methods. The coordination geometry of the ligand around the Cu(II) ion has been established as a distorted tetragonal pyramid. The peptide molecule behaves as a tridentate ligand via its amino (N2), amido (N1) nitrogens and carboxyl (O2) oxygens. The peptide nitrogen is found to be deprotonated.

Crystal and molecular structure of (+)-6,7?8,9?10,11-tri-O-isopropylidene-2,3-dideoxy-d-arabino-l-allo-undec-2-enono-1,4-lactone, C20H30O9

The crystal structure of the title lactone, C20H30O9, a potential precursor of uncommon 11-carbon sugar derivatives, has been determined by single-crystal diffraction methods. The compound crystallizes in the orthorhombic space groupP212121 witha=15.581(3),b=14.047(2),c=9.888(2) A, andZ=4. The structure was solved by direct methods and refined by full-matrix least-squares toR=0.054. The absolute configuration of the seven stereogenic carbon atoms was deduced as 4R, 5R, 6R, 7R, 8S, 9R, 10R, being (R)-(+)-glyceraldehyde its progenitor. An intramolecular O-H⋯O hydrogen bond is present. Weak interaction C-H⋯O links the molecules in sheets parallel to the (100) plane.

Crystal structure and properties ofcatena-poly[manganese(II)-μ-dichloro-μ-L-proline-k 2 o,o′] monohydrate

The crystal structure and some physico-chemical properties of MnCl2·Pro·H2O (Pro=L-proline) were studied. This compound is stable up to approximately 313 K. Upon heating the complex loses a molecule of water and is transformed into the oxide in two steps. The IR spectrum was recorded. The compound crystallizes in the orthorhombic space groupP212121 witha=7.112(2) A,b=10.196(2) A,c=13.249(3) A andZ=4. The manganese atoms in the polymeric chain are bridged by two chlorine atoms and oxygen atoms from the carboxylate group of L-proline. The Mn−Cl bond distances range from 2.535(1) A to 2.581(1) A, the Mn−O bond distances range from 2.135(2) A to 2.153(2) A and Mn−Mn bond distances are 3.556(1) A. One molecule of water is hydrogen-bonded with a nitrogen atom of the L-proline ring.

Molecular structure of 3-phenyl-5-methyl-4-isoxazolyl-penicillin sulfone (oxacillin sulfone): C19H19N3O8S

The crystal structure of oxacillin sulfone has been determined by single-crystal X-ray diffraction techniques and refined by full-matrix least squares. The penicillin molecule cocrystallizes with H2O in an orthorhombic space groupP212121 witha=10.303(7) A,b=26.735(17) A, andc=7.384(4) A. The calculated density is 1.526 g cm−3, with aZ value of 4. FinalR-factor is 0.035. The oxidation of the sulfur atom is discussed in terms ofS1 conformation of the penam moiety and in terms of hydrogen-bond formation between one oxygen of the sulfur atom and the amidic hydrogen of the C6 side-chain. A comparison with oxacillin and cloxacillin sulfoxide is also made.