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.     

Synthesis and structural characterization of 2,6-bis-(N-methylenemorpholino)-4-ter-butylphenol

The crystal and molecular structure of the title compound, C₂₀H₃₂N₂O₃, has been determined from X-ray diffraction data using CuK radiation (=1.5418 Å). The compound crystallizes in triclinic space groupP1^¯ with a=8.828(1),b=18.680(1),c=6.272(2)Å, =93.42(1), =0.24(2), =77.93(1)°,V=1009.4(2)ų, andZ=2. The structure was solved by direct methods and the full-matrix least-squares refinement leads the finalR-factor to 0.065 for 3481 observed reflections withI3(I). The phenyl ring is planar and the morpholino rings assume perfect chair conformation. The molecules are held together by van der Waals forces.DCB Contribution No. 810.     

The structure of β-(2)-nitrophenyl acrylonitrile

The structure of an important intermediate, IUPAC name: 2-(2-nitrophenyl) acrylonitrile has been studied by X-ray crystallography. C₉H₆N₂O₂ is monoclinic, space groupP2_1/c with cell dimensionsa=7.045(1),b=10.011(1),c=12.016(1) Å,=97.88(1)°,V=839.5(2) ų,Z=4,M _r =174.30,D ₀=1-38(1),D _x =1.39(1) g cm^–3,F(000)=360,T=293 K, (CuK)=1.5418 Å,=8.00 cm^–1,R=0.034 for 987 observed reflections. The aromatic ring is nearly planar. The Nitro group is rotated out of the aromatic plane by 26.5(1)°. There are three C-HO[3.469(3), 3.245(3), and 3.440(3) Å] and one C-HN[3.561(3) Å] intermolecular interaction.N.C.L. Communication No. 4847.     

Crystal structure and conformation of N-(t-butoxycarbonyl)-L-isoleucyl-L-alanine benzylester

C₂₂N₂O₅H₃₂,M _r =404.5, monoclinic,C2,a=21.781(5),b=5.065(1),c=22.333(4)Å,=112.81(2)°,V=2271.1(9)ų,D _calc=1.148 g cm³, (CuK )=1.5418 Å,=5.89 cm^–1,F(000)=848, room temperature,R=0.058 for 2178 unique reflections [I2.5(I)]. The peptide linkage is in thetrans conformation. The molecule adopts the-sheet structure. The crystal structure is stabilized by a three-dimensional network of N-HO and C-HO hydrogen bonds.DCB Contribution No. 813.     

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.     

C−Cl...π(Ar)...Cl−C,Cl...Cl and other interactions in the structures of two 6-substituted-2,4-bis(trichloromethyl)-1,3-benzdioxin's: (I) 6-carboxymethyl; (II) 6-propionyl,an antimethanogenesis food additive

C₁₂H₃Cl₆O₄, (I),M _r=428.91, triclinic, ,a=9.197(1),b=9.336(2),c=9.830(1) Å, =79.29(1), =83.33(1), =85.38(1)°,V=822.16,Z=2,D _x=1.73 Mg m^–3,F(000)=428, (MoK)=0.71069 Å, =10.62 cm^–1, room temperature, finalR=0.033 for 2573 unique counter reflections withF _o>4(F _o). C₁₃H₁₀Cl₆O₃, (II),M _r=426.94, triclinic, ,a=9.374(2),b=9.503(1),c=9.888(4) Å, =79.26(2), =82.10(3), =84.43(1)°,V=854.88,Z=2,D _c=1.66 Mg m^–3,F(000)=428, =0.71069 Å, =10.17 cm^–1, room temperature, finalR=0.030 for 2609 unique counter reflections withF _o>4(F _o). Compounds I and II are isostructural. Centrosymmetric dimers are formed by hydrogen bonds from the two methine hydrogen atoms to the carbonyl oxygen atom. The dimers are linked by Cl...(Ar)...Cl, Cl...O and Cl...Cl interactions to form a three-dimensional pattern. The geometry associated with these interactions is discussed in terms of the electrophile: nucleophile model.     

Structure of bis(2-pyridine-N-oxide) diselenide and its formation from tetraphenylantimony(V)selenopyridine-N-oxide

The structure of bis(2-pyridine-N-oxide) diselenide was determined by single crystal X-ray diffraction. The compound crystallized in the triclinic system and the structure was solved in the space group . The lattice constants were determined to bea=7.174(2),b=7.176(2),c=11.070(2) , =87.67(2)°, =73.68(2)°, and =89.57(2)°;Z=2,D _x=1.906 Mg m^–3. The final least squares refinement based on 1942 independent observed reflections yieldedR=0.033,wR=0.044. The Se–Se bond length is 2.326(1) and each Se is coordinated to the O atom of the corresponding N-oxide moiety at a distance of about 2.6 .     

Crystal and molecular structure of (endo)-1-methoxycarbonyl-5-ethoxycarbonyl-4,5,6,11b-tetrahydroisoxazolidino-[2,3-a]-β-carboline,C18H20N205

The structure of the title compound, C₁₈H₂₀N₂O₅, was determined by X-rays atT=290 K.M _r =344.366, monoclinic, space groupP2₁/c,a=11.4266(5),b=7.9563(15),c=18.9075(7) Å, =101.851(3)°,V=1682.3 ų,Z=4,D _x =1.360 Mg m^–3. CuK radiation (graphite crystal monochromator, X=1.54178 Å),(CuK)=7.91 cm^–1. Final conventionalR-factor=0.054,R _w =0.073 for 2787 observed reflections and 286 variables. The structure was solved usingMultan.     

Crystal structure of racemic 5-(p-nitrobenzoylamino)-5-methyl-4-oxo-1,3-dioxane

C₁₂H₁₂N₂O₆ crystallized from methanol in the monoclinic space group P2₁/c (Z=4) witha=13.333(4),b=10.154(3),c=9.597(2) Å and=102.37(2)°.M _r=280.24,V=1269.1(6) ų,D _x=1.466 g cm^–3,(Mo K)=0.71069 Å,=1.29 cm^–1,T=295 K. The structure was solved by direct methods and refined by full-matrix least-squares to a finalR (R _w)=0.049 (0.057) for 916 observed reflections. The molecules are linked by strong N-HO(4) hydrogen bonds with NO distance of 2.995(4) Å. The infinite racemic chains run in [001] direction.     

Crystal and molecular structure of 3-methoxy-B-nor-5,7-seco-1,3,5(10), 9(11)-estrapent-14-en-17-one-8-β-ethyl carboxylate

The crystal structure of the title compound has been determined by X-ray analysis. Crystal data: triclinic,P¯1, C₂₀H₂₂O₄,M _r =326,39,a=8.296(1),b=10.704(2),c=11.186(1) Å,=112.58(1),=100.81(1), =95.79(1)°,V _c =884.38(8) ų,D _x =1.225 g·cm^–1, (CuK)=1.54178 Å,=6.05 cm^–1,F(000)=384, room temperature,R=0.082 for 2410 unique reflections withF4 F. The conformation of the 3-methoxy-B-nor-5,7-seco-1,3,5(10), 9(11)-estrapent-14-en-17-one-8--ethyl carboxylate (1a) molecule is similar to that of the estranes. Since theB ring is not closed, the rotation around the C(9)-C(10) bond is possible and torsion of the molecule is observed.     

Crystal structure of tylophorine methiodide monohydrate,C25H30NO 4 + I−·H2O

The crystal structure of tylophorine (Chemical name 2,3,6,7 tetramethoxy phenanthro [9,10:6, 7] indolizidine. Contribution No. 0871.) methiodide monohydrate has been determined. C₂₅H₃₀NO ₄ ⁺ I^–·H₂0, triclinic, P,a=8.831(1)Å, b=10.842(2),c=13.902(2), =105.0(1)^o, =104.7(1), =97.3(1),V=1210.22ų, Z=2,D _x =1.428 g./cm^–3, (CuK)=1.54184Å, (CUK)=107.2 cm^–1, F(000)=544,T=295^oK,R=0.038,Rw=0.046, for 2331 observed reflections withI2(I). Apart from van der Waals forces, the structure is stabilized by two hydrogen bonds of the type Ow(H) ... O and Ow(H) ... I^– involving the water molecule as the donor and atom O4 of the methoxy group and I^– as acceptors.     

Synthesis and structural characterization of five new coordination polymer chain structures using a new,Z-shaped ligand, 2,2′-bis-(4-pyridylethynyl)tolane

Using the new ligand, 2,2-bis-(4-pyridylethynyl)tolane we have synthesized five new coordination polymers: HgBr₂[2,2-bis-(4-pyridylethynyl)tolane] (1), HgI₂[2,2-bis-(4-pyridylethynyl)tolane] (2), Ni(acetylacetonate)₂[2,2-bis-(4-pyridylethynyl)tolane] (3), Zn(acetylacetonate)₂[2,2-bis-(4-pyridylethynyl)tolane] (4), and Cu(hexafluoro acetylacetonate)₂[2,2-bis-(4-pyridylethynyl)tolane]CHCl₃ (5). 2,2-Bis-(4-pyridyl ethynyl)tolane is a rigid ligand with a Z-shape that promotes the formation of zig-zag chains. Compounds 1– 5 were characterized by single crystal X-ray diffraction; and compounds 1– 3 were additionally characterized by IR, elemental analysis, and thermogravimetric analysis. Compound 1 crystallizes in the monoclinic space group C2/c with a = 29.761(3) Å, b = 5.0531(5) Å, c = 16.7823(15) Å, = 104.090(2), V = 2447.9(4) ų, Z = 4. Each mercury is bound to two tolane ligands and two bromine anions, resulting in a tetrahedral coordination environment. Compound 2 crystallizes in the monoclinic space group P2/c, with a = 20.3061(17) Å, b = 5.6303(5) Å, c = 24.5459(19) Å, = 110.338(2), V = 2631.4(4) ų, Z = 4. Here also, each mercury is bound to two tolane ligands and two iodine anions in a tetrahedral coordination environment. The ligand orientation differs in compounds 1 and 2 being trans oriented in 1 and cis oriented in 2. Compound 3 crystallizes in the monoclinic space group P2₁/c with a = 14.5947(14) Å, b = 6.3082(6) Å, c = 18.3939(18) Å, = 112.112(2), V = 1568.9(3) ų, Z = 2. Each nickel is bound to two tolane ligands and two bidentate AcAc anions, resulting in an octahedral coordination environment. Compound 4, which is isostructural with 3, also crystallizes in the monoclinic space group P2₁/c with a = 14.6990(9) Å, b = 6.2724(4) Å, c = 18.6433(11) Å, = 112.8610(10), V = 1583.86(17) ų, Z = 2. Compound 5 crystallizes in the triclinic space group P-1 with a = 6.5487(4) Å, b = 11.6471(7) Å, c = 14.3225(9) Å, = 70.1360(10), = 89.3990(10), = 88.7680(10), V = 1027.18(11) ų, Z = 1. Each copper in 5 is bound to two tolane ligands and two bidentate hfAcAc anions, resulting in an octahedral coordination environment identical to that found in 3 and 4.     

Dinuclear complex of rhodium(III) with an amine-phenol ligand: synthesis and X-ray crystal structure

A new rhodium(III) complex of an amine-phenol ligand N,NN-bis-(2-hydroxybenzyl)1,3-diaminopropane was synthesized and characterized by X-ray diffraction studies. Diffraction data were collected by the-2 scan method using MoK. radiation. The structure was solved by conventional methods resulting in a final R factor of 0.037 for 1954 independent reflections (F _o >2(F _o )). The structure consists of a dinuclear complex with two -hydroxy bridges between the two Rh atoms. The overall charge of the molecule is neutral due to deprotonation of all phenolic groups. Crystal data: triclinic, space groupP¯1,a=7.308(3)Å;b=9.586(3)Å,c=12.686(5)Å, =87.51(2), =88.28(2), =71.70(3)°,V=866.6(6)ų;Z=2.     

Structural investigation on hexasubstituted benzene derivatives. Part 2: The structure of metadinitrotetramethylbenzene and molecular mechanics analysis on meta and ortho derivatives

C₁₀H₁₂N₂O₄ (M r=224.2) crystallizes in the monoclinic system, space groupP2₁/mwitha=15.462(4),b=7.926(3),c=8.972(3) Å;=90.2(1)°;V=1099.5(6) ų;Z=4;D _c=1.35 gcm^–3;(Cu-K)=8.6 cm^–1; =1.5418 Å;F(000)=472. The position of the molecule on a crystallographic mirror plane forces the NO₂ plane to be normal to the benzene ring. The-electron-withdrawing character of the NO₂ groups induces a deformation on the geometry of the benzene.     

Crystal and molecular structure of 1,N6-ethenoadenosine hydrochloride

The X-ray structure of 1,N ⁶-ethenoadenosine hydrochloride, C₁₂H₁₄N₅O₄Cl, has been determined from three-dimensional diffractometer data and refined by full-matrix least-squares techniques. The crystals are monoclinic:P2₁ No. 14,a=6.1540(5),b=18.511(1),c=6.7412(4) Å,=112.602(5)°,andZ=2; finalR=0.045 for 2662 observed reflections. The crystal and molecular structure of Ado·HC1 is very similar to that of Ado·HC1. On the other hand, the dimensions and conformation of the Ado·H⁺ cation are drastically different from those of Et Ado·H⁺. The adenosine·H⁺ moiety is not planar but has an S shape. The ribose is 2-endo-3-exo puckered, with ag ⁺ side chain; the glycosidic torsion angle is in theanti region. The structure contains a three-dimensional network of H bonds in which also C-HA interactions seem to play an important role. There is no base stacking in the structure.     

Crystal structure of 14, α-hydroxy,sandarocopimar-7, 15-diene-19-oic acid

C₂₀H₃₀O₃, M _r =318.46, Monoclinic,P2₁,a=12.232(2) ,b=11.491(2) ,c=14.160(3) , =115.2°(3),V=1800.3(7) ³,Z=4,D _x =1.18 Mg m^–3, (CuK)=1.5418 , =5.3 cm^–1,F(000)=696,T=298 K. FinalR=0.044 for 2645 reflections withI>2. The two crystallographically independent molecules in the unit cell adopt essentially similar conformations. The structure reveals atrans relationship between the hydrogen at C(9) and the methyl group at C(20). The stereochemistry at C(13) is S. Apart from van der Waals forces the structure is stabilized by hydrogen bonds.     

Structure of 17β-hydroxy-4-pregnen-20-yn-3-one,C21H28O2

The crystal structure of 17-hydroxy-4-pregnen-20-yn-3-one, C₂₁H₂₈O₂, was determined by means of X-ray diffraction methods.M _r=312.5, space groupP2₁,a=6.493(1),b=21.065(3),c=6.478(1) Å,=105.97(1)°,V _c=851.9(3) ų,Z=2,D _x=1.22 Mg m^–3, CuK radiation (=1.54184 Å),(CuK)=5.5 cm^–1,F(000)=340. The structure was solved withMultan; final conventionalR=0.032 (R _w=0.032) for 1803 reflections. The molecule studied (I) has an overall conformation almost identical to 19-norethindrone (II), although ringA of molecule (I) is slightly more bent toward the direction of the steroid skeleton in comparison with molecule (II).     

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.     

Crystal and molecular structure of (exo)-1-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, orthprombic, space groupP2₁2₁2₁,a=9.350(5),b=11.954(2),c=15.455(3) Å,V _c =1727.3 ų,Z=4,D _c =1.324 Mg m^–3. CuK. radiation (graphite crystal monochromator, =1.54178 Å),(CuK)=7.70 cm^–1. Final conventionalR-factor=0.065,R _w =0.086 for 2887 observed reflections and 265 variables. The structure was solved usingMultan.     

Crystal structure of an intermediate in the synthesis of artemisinin

C₁₄H₂₂O₃,M _r =238.33, P2₁2₁2₁,Z=4,a=6.892(2),b=11.453(1),c=17.159(5) Å. [1R–[1(R^*), 4, 4a, 8a]]–,4-Dimethyl-decahydro-7-oxo-1-naphtaleneacetic acid. The cyclohexane ring adopts a chair conformation and thecis-fused cyclohexanone ring is in a slightly distorted chair conformation. The molecular packing involves an hydrogen bond and C–H...O contacts.