X-ray and NMR studies on the rotational isomerism about the C(5)-C(6) bond of 6-substituted methyl 2,3,4,-tri-O-acetyl-6-X-α-D-glucopyranoside derivatives

The rotamers about the C(5)–C(6) bond of a series of 2,3,4-tri-O-acetyl-6-X--D-glucopyranozide derivatives resulting by substitution at C(6) or O(6) have been studies with¹H-NMR spectroscopy (400 MHz) and X-ray structure analysis. The methyl 2,3,4-tri-O-acetyl-6-O-triphenylmethyl--D-glucopyranoside and the N-(I-O-methyl-2,3,4-tri-O-acetyl--D-glucopyranose-6-yl)-pyridinium nitrate crystallize in the P2₁ space group with =14.940(1),b=11.232(1),c=9.0773(7), and =94.480(7) anda=7.670(1),b=15.384(3),c=9.624(1) and =104.90(1), respectively; the methyl 2,3,4-tri-O-acetyl-6-O-nitro--D-glucopyranoside and methyl 2,3,4-tri-O-acetyl-6-O-deoxy-6-iodo--D-glucopyrano-side crystallize in the P2₁2₁2₁ space group witha=5.630(1),b=14.360(1) andc=22.388(3), anda=5.556(1),b=14.303(6) andc=21.963(6), respectively.     

Crystal structures and energy refinement of some 2,2′-disubstituted biphenyl compounds

Synthesis and structural determination by X-ray crystallography of three substituted biphenyl structures are reported: (2) is monoclinic P2₁/n witha=10.805(4),b=8.079(3),c=16.232(6)Å, =100.96(5)°: (4) is monoclinic P2₁/n witha=9.966(3),b=10.007(3),c=13.053(4) Å, =96.74(5)°; (5) is triclinic witha=12.033(5),b=16.903(8),c=9.752(4)Å, =94.70(3)°, =112.56(3)° =76.12(3)°. In all compounds the biphenyl has two identical substituents in an ortho position to the center inter-ring bond and present variable inter-ring twist angles. In the process of investigating molecular geometry, we are interested in studying whether the calculated conformations of our molecules can fit the crystallographic structures.     

Polymorphs of nitrofurantoin. 2. Preparation and X-ray crystal structures of two anhydrous forms of nitrofurantoin

The preparation and X-ray crystal structures of two polymorphs of the antibacterial drug nitrofurantoin are reported. The -polymorph is triclinic, space groupP¯1 witha=6.774(1),b=7.795(1),c=9.803(2)Å, =106.68(1),=104.09(2), =92.29(1)°,Z=2. The-polymorph is monoclinic, space groupP2₁/n witha=7.840(5),b=6.486(1),c=18.911(6)Å,=93.17(3)°,Z=4. The nitrofurantoin molecules adopt the same, planar conformation in both polymorphs. Both crystal structures are built up from layers held together by van der Waals forces. In each polymorph, intralayer cohesion is effected by N-HO and C-HO hydrogen bonds, but their arrangements differ in the two crystals. The significance of the C-HO hydrogen bond, now known to occur in four modifications of nitrofurantoin, is discussed.     

Crystal structures of five policyclic compounds related to the natural product forskolin

(3(Z),4,6a,9a,9b)-(±)-3a,4,6a,7,8,9,9a,9b-octahydro-4,7,7, 9b-tetramethyl-3a-[3-(methoxymethyloxy)-3-methyl-1-butenyl]-5H-naphto[1,8-de]-1,3-dioxin-6-one (I), C₂₂H₃₆O₅,M _r=378.51, monoclinic,P2₁/n,a=6.330(1),b=14.576(2),c=22.837(2)Å,=93.04(1)°,V=2104.1(2)ų,Z=4,D _c=1.19 Mg/m³, (MoK)=0.71069Å,=0.8 cm^–1,F(000)=832,T=298 K,R=0.054 for 1971 observed reflections; (7a,10a,10b,12)-(±)-7a,9, 10,10a,10b,11,12,12a-octahydro-2,2,10,10,10b,12a-hexamethyl-2H,8H-1-benzopyrano[4a,5,6,-de][1,3,2]-benzodioxin-11-one (II), C₂₀H₂₉O₄,M _r=334.5, triclinic,P-1,a=10.595(2),b=12.152(1),c=8.073(1)Å,=106.53(1),=105.65(1), =66.29(1)°,V=897.9(2)ų,Z=2,D _c=1.24 Mg/m³, (MoK)=0.71069Å,=0.8 cm^–1,F(000)=362,T=298 K,R=0.046 for 2848 observed reflections; (7a,10a,10b,12, 12a)-(±)-7a,9,10,10a,10b,11,12,12a-octahydro-2,2,10,10,10b,12a-hexamethyl-2H,8H-1-benzopyrano[4a,5,6-de][1,3,2]-benzodioxin-11, 12-diol (III), C₂₀H₃₂O₅ (two molecules in the asymmetric unit),M _r=352.2, triclinic,P-1,a=12.948(3),b=13.615(3),c=12.197(4)Å,=101.16(2),=111.88(2), =69.48(2)°,V=1863.8(9)ų,Z=2,D _C=1.26 Mg/m³,(MoK)=0.71069 Å,=0.8 cm^–1,F(000)=768,T=298 K,R=0.060 for 4570 observed reflections; 4-acetoxy-4-[[(4a,5,8a)-(±)-hexahydro-4a,6,6-trimethyl-4H-1,3-benzodioxin-4-one]-5-yl]butan-2-one (IV), C₁₇H₂₆O₆,M _r=326.4, monoclinic,P2₁/c,a=10.495(2),b=12.050(2),c=14.216(2)Å,=108.51(1)°,V=1704.8(5)ų,Z=4,D _c=1.27 Mg/m³,(MoK)=0.71069 Å,=0.9 cm^–1,F(000)=704,T=298 K,R=0.049 for2455 observed reflections; (3a,4,5,6,6a,9a,9b)-(±)-4,5-epoxy-decahydro-3, 3a-dihydroxy-2-ethoxy-4,7,7,9b-tetramethyl-naphto-[1,8-bc]-pyran-6-ol-acetate (V), C₂₀H₃₂O₇,M _r=383.5, monoclinic,C2/c,a=10.353(2),b=17.975(3),c=21.188(3)Å,=91.29(1)°,V=3942(1)ų,Z=8,D _c=1.29 Mg/m³,(MoK)=0.71069 Å,=0.8 cm^–1,F(000)=1664,T=298 K,R=0.051 for 2120 observed reflections. We report here the complete structures of four decalin derivatives (compoundsI, II, III, V) and one related compound (compoundIV) synthetized in order to find an efficient synthetic approach for the natural productforskolin.     

Distortions in nitramine substituted cubanes: The structures of N,N′-dinitro-1,4-diaminocubane,N,N′-dinitro-N,N′-(2-pyridyl)-1,4-diaminocubane,and 1,2,4,7-tetrakis(N-methoxycarbonylnitramino)cubane

The structures of three nitramine substituted cubane molecules, N,N-dinitro-1,4-diaminocubane (1), N,N-dinitro-N,N-(2-pyridyl)-1,4-diaminocubane (2), and 1,2,4,7-Tetrakis(N-methoxycarbonylnitramino)-cubane (3), have been determined.1 crystallized in the space group P2₁/a with cell dimensionsa=6.545(1),b=9.331(1),c=7.459(1) Å, =105.80(1),2 crystallized in the monoclinic space group P2₁/a with cell dimensionsa=7.545(2),b=8.697(3),c=12.406(4 Å, =96.28(3)°, while3 crystallized in the monoclinic space group P2₁/c with cell dimensionsa=10.866(3),b=6.866(2),c=16.167(6) Å, =108.79(3)°. The metrical parameters of the cubane skeleton showed no significant deviations from those found in other similarly substituted cubane molecules. For2 and3 there were considerable distortions of the nitramine moiety from planarity in contrast to1 where the nitramine moiety was almost exactly planar. The bond distances and angles for the nitramine group in1 indicates a substantial introduction of double bond character into the N–N bond in1, achieved by delocalization of the amine lone pair, compared with2 and3.     

Crystal and molecular structure of 1-methyl-2,3,5,6-tetraphenylpiperidin-4-ol,C30H29NO

The structure of the the title compound, C₃₀H₂₉NO, was determined by X-rays.M _r =419.57, triclinic, space groupP1,a=5.8922(12),b=8.5855(11),c=12.2216(20) Å,=78.145(12)°,=79.181(15)°, =76.108(14)°,V _c =581.1(1) ų,Z=1,D _x =1.199 Mg m^–3. CuK radiation (graphite crystal monochromator, =1.54184 Å),(CuK)=5.17 cm^–1,T=290K. Final conventionalR-factor=0.039,R _w =0.042 for 2795 observed reflections and 377 variables. The structure was solved usingMultan andDirdif. With a view to determining the conformational preference of the piperidine ring when it is highly sustituted with a bulky group like the phenyl group, the present X-ray investigation was undertaken.     

Crystal and molecular structure of 5-ethoxy-4-methylene-exo-10-oxatricyclo[5.2.1.02,6]-deca-8-ene-3-ol,C12H16O3

The structure of the title compound, C₁₂H₁₆O₃, was determined by X-rays.M _r =208.26, triclinic, space groupP¯1,a=7.802(2),b=8.449(2),c=9.069(1) Å,=90.79(1)°,=105.57(1)°, =106.07(1)°,Z=2,D _x =1.26 Mg m^–3; MoK radiation (graphite crystal monochromator, =0.71069 Å),(MoK)=0.96 cm^–1,T=290 K. Final conventionalR-factor=0.046,R _w =0.067 for 3009 observed reflections and 184 variables. The structure was solved using Patterson methods andDirdif, and the resulting all cis-endo configuration of the alcohol group on C(3) and the ethoxy group on C(5) shows that the stereochemistry of the metal-mediated addition reaction involved is solely determined by steric factors.     

Pentacoordinated tin(II); crystal structure of dichloro-[2,2′∶6′,2″-terpyridyl]-tin(II)

The crystal structure of a well-defined 5-coordinate complex, dichloro-(2,26, 2-terpyridyl)-tin(II), is described. The stereochemistry of this complex is strongly influenced by the stereochemically active pair of electrons, illustrating clearly the potential donor capabilities of this molecule. The complex (C₁₅H₁₁Cl₂N₃Sn) crystallizes in the monoclinic space groupC2/c (No. 15) witha=15.770(5),b=9.450(2),c=10.482(2) Å,=97.53(2)°,Z=4. The finalR value is 0.029 for 1085 observed reflections.     

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)Å,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)° and=30(1)°. The C4-C5 conformation is + sc with =46.7(7)°. The structure is stabilized by N-HN, N-HO and O-HO hydrogen bonds and C-HO close contacts.     

Crystal and molecular structure of (exo)-2-methoxycarbonyl-5-ethoxycarbonyl-4,5,6,11b-tetrahydroisoxazolidino-[2,3-a]-β-carboline,C18H20N2O5

The structure of the title compound, C₁₈H₂₀N₂O₅, was determined by X-rays atT=290 K.M _r =344.366, monoclinic, space groupP2₁/c,a=13.7850(8),b=8.8951(7),c=15.1603(11) Å, =111.410(6)°,V _c =1730.7 ų,Z=4,D _x =1.322 Mgm^–3. Cu K radiation (graphite crystal monochromator, =1.54178 Å),(Cu K)=7.69 cm^–1. Final conventionalR-factor=0.057,R _w =0.076 for 2160 observed reflections and 271 variables. The structure was solved usingMultan.     

Crystal and molecular structure of (exo)-2-phenyl-5-ethoxycarbonyl-4,5,6,11b-tetrahydroisoxazolidino-[2,3-a]-β-carboline,C22H22N2O3

The structure of the title compound, C₂₂H₂₂N₂O₃, was determined by X-rays atT=290 K.M _r =362.427, orthorombic, space groupPbca,a=11.666(4),b=15.691(1),c=20.931(1) Å,V=3831.4 ų,Z=8,D _x =1.257 Mgm^–3. CuK radiation (graphite crystal monochromator, =1.54178 Å),(CuK)=6.42 cm^–1. Final conventionalR-factor=0.050,R _w =0.062 for 2552 observed reflections and 301 variables. The structure was solved usingMultan.     

Crystal and molecular structure of [rac-1S,2S,-3S,4R]methyl 2-benzoyl-3,4-dimethyl-4-phenylcyclobutane-1-carboxylate,C21H22O3

The structure of the title compound C₂₁H₂₂O₃, was determined by X-rays.Minr=322.4, monoclinic, space groupP2₁/a,a=11.960(2),b=14.275(3),c=10.858(2) Å,=103.20(2)°,V _c =1804.8 ų,Z=4,D _x =1.223 Mg m^–3. CuK radiation (graphite crystal monochromator,=1.54184 Å),(CuK)=6.53 cm^–1,F(000)=688, T=290 K. Final conventionalR factor=0.050,R _w =0.069 for 1679 unique reflections and 284 variables. The structure was solved usingMultan.     

Two acetylamino derivatives of 2,4-bis(trichloromethyl)-1,3-benzdioxin showing different types of hydrogen bonding: (a) (C13C)CH⋯O=C and (b) N-H⋯O=C

8-Acetylamino-6-methyl-2,4-bis(trichloromethyl)-1,3-benzdioxin, (I), is monoclinic,P2₁/c,a=15.174(4),b=11.977(7),c=9.911(3)Å,=99.72(2)°. 6-Acetylamino-2,4-bis(trichloromethyl)-1,3-benzdioxin, (II), is monoclinic,P2₁/_n,a=5.927(4),b=40.623(1),c =7.120(3)Å,=91.39(4)°. In compound (I) the imino hydrogen atom is locked in an intramolecular hydrogen bond to the proximate oxygen atom of the heterocyclic ring and is not available for intermolecular hydrogen bonding. Instead the weakly acidic hydrogen atom [Cl₃C-C(2)]H takes part in a hydrogen bond to the carbonyl oxygen atom in another molecule. In compound (II) a normal intermolecular hydrogen bond of the type N-HO=C occurs. The 6-acetylam-ino group is twisted about the (C_Ar-N) bond such that the angles NHO=C, C_ArH_ArO=C, NHOH_ArC_Ar, at the carbonyl oxygen group total 360° (where NH is in the related molecule). The packing in both compounds takes the form of infinite chains and in compound (II) partial overlap of the aromatic ring and the acetylamino group, with very little offset, also occurs.     

Crystal and molecular structure of (exo)-1-carboxymethyl-5-ethoxycarbonyl-4,5,6,11b-tetrahydroisoxazolidmo-[2,3-a]-β-carboline,C18H20N2O5

The structure of the title compound C₁₈H₂₀N₂O₅, was determined by X-rays atT=290 K.M _r =344.366, monoclinic, space groupP2₁/c,a=15.589(4),b=7.619(1),c=16.792(4) Å, =111.47(2)°,V=1856.1 ų,Z=4,D _x =1.23 Mg m^–3. CuK radiation (graphite crystal monochromator, =1.54178 Å),(CuK)=7.17 cm^–1,F(000)=728. Final conventionalR-factor=0.075,R _w =0.106 for 2266 observed reflections and 274 variables. The structure was solved usingMultan.     

Crystal and molecular structures of O,O-propan-1,3-dithionobenzoate (2TBZ-A), O,O-2,2-dimethylpropan-1,3-dithionobenzoate (2TBZ-B), and O,O,O,O-pentaerythritoltetrathionobenzoate (4TBZ)

The crystal and molecular structures of three thionobenzoates have been determined: O,O-propan-1,3-dithionobenzoate (2TBZ-A) is tetragonal witha=13.086(2),c=19.048(2) Å, space groupI4₁/a,Z=8; O,O-2,2-dimethylpropan-1,3-dithionobenzoate (2TBZ-B) is monoclinic witha=13.851(5),b=12.428(3),c=10.996(4) Å,=104.01(4)°, space groupP2₁/c,Z=4; and O,O,O,O-pentaerythritol-tetrathionobenzoate (4TBZ) is triclinic witha=15.423(4),b=10.924(3),c=10.698(2) Å,=112.43(2),=100.64(2), =104.57(2)°,Z=2, space groupP¯1. The structures were all solved by direct methods and refined by least squares toR=0.046 for 886 reflections (2TBZ-A),R=0.075 for 1458 reflections (2TBZ-B) andR=0.075 for 2975 reflections (4TBZ),I>3(I) in each case, CuK radiation, =1.5418 Å. The minimum S---CH₂ intramolecular distances in these three structures are significantly larger than the minimum corresponding distance in O,O,O-propan-1,2,3-trithionobenzoate (3TBZ) (Moore and Palmer, 1990), thus providing a possible explanation of why 2TBZ-A, 2TBZ-B, and 4-TBZ are inert with respect to pyrolitic solid-state isomerization; whereas 3TBZ readily undergoes thermally induced rearrangement (Das, 1978; Hedgley, 1981).     

Structure and spectroscopic properties of the 1∶2 complex of 3,5-dimethylpyridine with 3,5-dinitrobenzoic acid and its deuterated analog

The structure of the nondeuterated and deuterated complexes of 3,5-dimethylpyridine with 3,5-dinitrobenzoic acid in a stoichiometric ratio 12 have been determined by X-ray diffraction methods. The crystals of the nondeuterated complex are triclinic, space groupP¯1 witha=9.409(9),b=10.813(7),c=12.310(7)Å,a=95.75(5),=108.17(7), =91.46(7)° andZ=2. The crystals of the deuterated complex are monoclinic, space groupP2₁/c, witha=11.680(6),b=8.451(4),c=24.382(9)Å,=102.94(4)° andZ=4. Both structures have been solved by direct methods and refined toR=0.035 for 2235 and toR=0.044 for 1938 independent reflections for nondeuterated and deuterated crystal, respectively. The structures consist of 3,5-dimethylpyridinium cations and hydrogen (or deuterium) bis(3,5-dinitrobenzoate) anions. The N(1)⁺-H(N1)O(1)^–, O(7)-H(7)O(2), N(1)⁺-D(1)O(l)^– and O(7)-D(7)O(2) bond lengths are 2.644(4), 2.499(3), 2.739(5), and 2.526(5)Å, respectively. The IR spectra of both complexes within the proton (or deuteron) absorption range have been studied.     

Synthesis and crystal and molecular structure of newN-substituted γ-hydroxybutyramides

TheN-(2-phenylethyl)amide of-(1, 1-ethylenedioxy)-ethyl--hydroxybutyric acid (II) and theN-(p-methoxybenzyl)amide of-(1, 1-ethylenedioxy)-ethyl--hydroxybutyric acid (III) have been synthesized and the crystal structure ofIII has been solved. CompoundIII, C₁₆H₂₃O₅N, crystallizes in the monoclinic space groupP2₁/c witha=12.572(2),b=11.149(2),c=12.317(2) Å and=106.53(1)°. The structure was solved by direct methods, and refined by full-matrix least squares to giveR=0.040 (R _w =0.047) for 2004 intensities. The dioxolane ring has a deformed half-chair conformation.     

Crystal structure of 1,2,4,6-tetraphenylpyridinium tetrabromoferrate(III)

The title structure, which belongs to the triclinicP¯1 space group witha=13.901(4),b=10.732(1),c=10.570(8)Å=109.14(4),=96.17(4), =90.34(2)°, is refined toR=0.052 for 2985I3(I) reflections. The structure consists of a non-interacting 1,2,4,6-tetraphenylpyridinium and tetrahedral tetrabromoferrate (III) ions.     

Crystal structure ofcatena-O,O′-diethylphosphonoacetatotriphenyltin

Triphenyltin diethylphosphonoacetate, which crystallizes in the monoclinc space groupP2₁/c (a=15.154(4),b=9.159(3),c=17.685(4) Å, =91.410(8)°), adopts a polymeric structure in which planar triphenyltin cations (_C—Sn—C=357.3(6)°) are axially linked by the diethylphosphonoacetato anions (Sn–O_esteryl=2.129(3), SnO_phosphoryl=2.420(3) Å; O–SnO=171.9(1)° into chains that propagate by translations along theb-axis. The structure has been erfined toR=0.037 for 3384I3(I) reflections.     

Conformational study on aryl ketones: The structure of 2,6-dimethyl-1,5-di-(2-methyl)-propanoylnaphthalene

C₂₀H₂₄O₂ (M _r =296.4) crystallizes in the monoclinic system, space groupC2/c witha=24.154(4),b=8.001(2),c=12.751(3) Å;=136.8(1)°;V=1686.9 ų,Z=4,D _c =1.17 g cm^–3,(Cu-)=5.4 cm^–1,=1.5418 Å,F(000)=640. The molecule in the solid state adopts a centrosymmetric geometry with the molecular center of symmetry coincident with a crystallographic center of symmetry. This fact forces the molecule to themeso conformation.