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 crystal structure of a new bimetallic complex of diethylenetriamine pentaacetic acid: [YbAg2(dtpa)(H2O)]·3H2O

The reaction between Yb(III) nitrate, Ag(I) nitrate, and the diethylenetriamine pentaacetate (dtpa) ligand gives rise to a bimetallic complex. [YbAg₂(dtpa)(H₂O)]·3H₂O is triclinic, space group P-1, with a = 8.768 (3), b = 9.862 (2), c = 13.055 (2) Å, = 75.40 (1), = 83.00 (2) and = 87.46 (2)°. Each dtpa is coordinated to one ytterbium and six silver atoms. The resulting crystal structure can be described as 2D packing. In the layers, the ytterbium atoms are connected through [Ag(COO)]₂ dimers. Strong hydrogen bonds, involving the noncoordinated water molecules, ensure crystal cohesion.     

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.     

Hydrogen-bonded networks formed by substituted 2,6-diarylpyrazines

The X-ray crystal structure of 2,6-bis(4-hydroxyphenyl)pyrazine and 2,6-bis(4carboxyphenyl)pyrazine are reported. The structure of the 2,6-bis(4-carboxyphenyl) pyrazine dimethylsulfoxide complex (C₁₈H₁₂N₂O₄)(C₂H₆OS) is triclinic, P-1, with a = 7.9933(8), b = 10.7165(10), c = 12.1337(12) Å, = 66.385(2), = 84.070(2), = 77.219(2). The structure comprises stacked two-dimensional sheets of the hydrogen bonded complex. The two-dimensional sheets comprise hydrogen-bonded ribbons of the (carboxyphenyl)pyrazine that are connected by bridging hydrogen bonds to the dimethylsulfoxide. The structure of 2,6-bis(4-hydroxyphenyl)pyrazine, C₁₆H₁₂N₂O₂, is monoclinic, P2₁/c, with a = 10.6107(13) Å, b = 14.6743(18) Å, c = 8.3772(10) Å and = 104.982(2). The structure reveals that two-dimensional hydrogen-bonded sheets are formed with pyrazine–phenol and phenol–phenol hydrogen bonds.     

Synthesis,thermal reactivity and structure of 1,2-bis(4-hydroxy-3-methoxyphenylethynyl)benzene

The crystal structure of the new enediyne 3 was determined by X-ray diffraction. 3 crystallizes in the orthorhombic space group Pbca (No. 61) with a = 12.7148(9) Å, b = 7.4872(8) Å, c = 38.890(4) Å, = = = 90 and Z = 8. The three-dimensional structure is characterized by an 8-membered cyclic array linking four molecules of 3 by hydrogen bonding between phenolic and methoxy groups. Furthermore, stabilization by –-stacking and CH s interactions is present. The important cd distance (between the two terminal acetylene carbons of the enediyne) which is relevant for the Bergman cyclization, was determined to 401 pm, being in good agreement with the high cyclization barrier ( G = 147.9 kJ mol^–1 at 220C) that was determined by differential scanning calorimetry (DSC).     

Structural and spectral studies of binuclear copper(II) 2-acetylpyridine 3-azacyclothiosemicarbazones with sulfato bridges

Structures of two binuclear copper(II) complexes with sulfato bridges and tridentate 2-acetylpyridine 3-azacyclothiosemicarbazone ligands have been solved. The complex-sulfato-bis{(2-acetylpyridine 3-hexamethyleneiminyl-thiosemicarbazonato)copper(II)} N,N-dimethylformamide, [Cu(Achexim)]₂SO₄·DMF, has the following structural properties: triclinic, P1¯(#2), a = 12.314(4), b = 15.885(4), c = 10.959(4) Å, = 103.25(2), = 103.60(2), = 109.94(2)°, V = 1843(2) ų, and Z = 2; for -sulfato-bis{(2-acetylpyridine 3-piperidylthiosemicarbazonato)copper(II)}chloroform, [Cu(Acpip)]₂SO₄·CHCl₃: triclinic, P1¯(#2), a = 11.657(1), b = 17.101(2), c = 10.338(1) Å, = 98.51(1), = 109.294(7), = 107.016(9)°, V = 1790.3(4) ų, and Z = 2. The size of the azacyclo ring significantly affects the stereochemistry of these binuclear complexes.     

A comparison of the coordination preferences of Zn, Co, and Cd(II) with the heteroscorpionate ligand (2-hydroxy-3-t-butyl-methylphenyl)bis (3,5-dimethylpyrazolyl)methane

Reaction of the Zn, Cd, or Co nitrate salts with the deprotonated ligand (2-hydroxy-3-t-butyl-methylphenyl)bis(3,5-dimethylpyrazolyl)methane (L1O^–) in methanol produced the following complexes: [(L1OH)Zn(NO₃)₂] in two isomorphs, a = 40.983(8) Å, b = 9.571(2) Å, c = 15.667(8) Å, = 90, = 106.38(1), = 90, C2/c, and a = 13.027(3) Å, b = 14.781(4) Å, c = 16.107(3) Å, = 90, = 105.30(1), = 90, P2₁/n; [(L1OH)Cd(pz)(NO₃)₂] a = 14.7476(2) Å, b = 13.5411(2) Å, c = 16.7223(2) Å, = 90, = 110.3840(10), = 90, P2₁/c; and [(L1O)Co(pz)(NO₃)] a = 11.4240(2) Å, b = 13.4498(2) Å, c = 13.8056(2) Å, = 105.2080(10), = 105.8130(10), = 112.7470(10), P . The Zn adopts a pseudotetrahedral four-coordinate geometry where the potentially tridentate ligand is actually bidentate with a protonated and uncoordinated phenoxy arm. The Co complex is pseudooctahedral six-coordinate where the phenoxy arm is deprotonated and coordinated. Finally the Cd complex is seven-coordinate but the metal is not coordinated through the phenoxy group that is again protonated.     

Synthesis and X-ray crystal structure of an organometallic phosphonate [η6-1,2-C6H4(OCH3)(P(O)(OCH2CH3)2)]Cr(CO)3

The chiral, racemic, arene phosphonate complex, [t⁶-1,2-C₆H₄(OCH₃t)(P(O)(OCH²CH₃t)²)t] Cr(CO)₃ (1), was prepared via the reaction of 1,2-C₆H₄(OCH₃)(P(O)(OCH²CH₃)²) with Cr(CO)₆ in refluxing dioxane/THF. The title complex crystallized in P1 with the cell dimensions: a = 8.4893(4) Å, b = 11.0638(9) Å, c = 11.2135(8) Å, and = 62.151(8), = 105.154(5), = 112.426(6), giving a volume of 856.34(10) ų. The conformation of 1 is described as eclipsed (E) in which the methoxy substituent eclipses a carbonyl ligand of the tripod, and the phosphonate substituent is staggered.     

Hydrogen bonding in labdane diterpenoids, labda-7,12(E),14-triene-17-oic acid and labda-12(Z),14,17-triene-18-oic acid

Two labdane diterpenoids, labda-7,12(E),14-triene-17-oic acid (1) and labda-12(Z),14,17-triene-18-oic acid (2), C₂₀H₃₀O₂, have been isolated from Croton oblongifolius. Both 1 and 2 crystallized in the monoclinic system, space group C2, with cell dimensions of a = 21.912(1) Å, b = 7.4002(4) Å, c = 11.5079(7) Å, = 101.999(1)^o and a = 21.308(2) Å, b = 11.9067(9) Å, c = 7.5606(6) Å, = 100.763(1)^o, respectively. Compound 1, a rare example of carboxylic group bound to a cyclohexene ring, forms an infinite intermolecular hydrogen-bonded polymer [O1 O2(–x + 1/2, y + 1/2, –z + 2) 2.697(2) Å], whereas molecules of compound 2 are linked to form an asymmetric hydrogen-bonded dimer [O1 O2(–x, y, –z) 2.657(3) Å].     

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.     

Short H· · ·H distances in norbornene derivatives

A short H···H intramolecular interaction was reported previously for an anhydride of syn-sesquinorbornene. The synthesis and structure of a such an anhydride with an additional five-membered dithiole ring has been investigated. While hydrogen atom positions are not accurately located, the 1.62 Å separation indicates this molecule is a candidate for the shortest H···H interaction. Two cycloadducts of norbornadiene, which literature suggests might exhibit additional short interactions, are reported also; however, the isomers with minimal intramolecular interactions are the isolated products. C₂₂H₂₀O₃S₂, 3, crystallizes in P with a = 10.881(4), b = 13.712(8), C = 6.548(8) Å, = 101.32(6), = 107.49(5), = 90.49(4)°, D _calc = 1.445 g cm^–3, and Z = 2, C₂₁H₂₀O₄Cl₈, 5, in P2₁/n with a = 8.168(2), b = 13.488(4), c = 23.500(6) Å, = 94.72(2)°, D _calc = 1.597 g cm^–3, and Z = 4, C₂₁H₂₈O₄, 6, in P> with a = 12.667(2), b = 12.792(2), c = 12.540(2) Å, = 113.51(1), = 98.18(1), = 74.39(1)°, D _calc = 1.276 g cm^–3, and Z = 4.     

Crystal and molecular structure of glutaconic acid

Crystals of Glutaconic acid, C₅O₄H₆, are triclinic, space group P , with the cell dimensions (294 K), a = 4.843(1) Å, b = 10.188(1) Å, c = 12.609(1) Å, = 83.46(1)°, = 80.02(1)°, = 78.71(1)°, V = 598.8(3) ų with D _m = 1.47, D _x = 1.443 gcm ^–3. There are two independent molecules in the asymmetric unit. The crystal structure was solved by multi solution techniques with three-dimensional data collected (to the limit of 2_max of 154° for Cu K) on a CAD-4 diffractometer. The crystal structure was refined by full matrix least squares method to a final R value of 0.058 for 1894 reflections (I 2). The two independent molecules are conformationally similar. In both the molecules, the carboxyl ends are trans to each other with respect to the central C=C double bond in the structure. The molecules are self-paired through dimeric type of hydrogen bonding involving the terminal carboxyl groups, characteristic of many dicarboxylic acid structures. The crystal structure is stabilized by a series of O–HO hydrogen bonds of the glutaconic acid dimeric units. Free radicals have been shown to be involved in a number of chemical and biological processes and lipid peroxidation is one such process. Glutaconic acid was chosen as a simple unsaturated model of a fatty acid. When irradiated with X-rays, it was found to form a stable free radical structure. ESR (electron spin resonance) and ENDOR (electron nuclear double resonance) studies were used to characterize the free radical structure and correlate with the X-ray structure. The free radical was found to be HOOC–CH=CH–CH–COOH with the glutaconic acid in the trans conformation. The damage occurs at the -carbon atom (the first carbon of the double bond). The damage consists of a loss of an hydrogen atom. This results in an unpaired electron in the p-orbital delocalized over the three central carbon atoms. The two -proton couplings were resolved in the ENDOR spectrum. ESR spectra show that the two molecules are magnetically similar that is in agreement with the crystal structure that reveals that the two independent molecules are conformationally similar. This is the characteristic type of damage that occurs in lipids when they form free radicals that in turn reacts with oxygen and other compounds and ultimately results in cellular damage.     

Synthesis and crystal structure of the perchlorate salt of diprotonated N,N′-bis(1-methylimidazole-2-methyl)1,5-diazacyclooctane

The diprotonated perchlorate salt of a new 1,5-diazacyclooctane (DACO) mesocycle functionalized by two imidazole pendants, N,N-bis(1-methylimidazole-2-methyl)-1,5-diazacyclo-octane (C₁₆H₂₈N₆Cl₂O₈), has been synthesized and the structure determined by X-ray diffraction analysis. The title compound crystallizes in the monoclinic system, space group P2₁/c with a = 11.964(2), b = 13.251(3), c = 14.741(3) Å, = 106.00(3)°, Mr = 503.34, V = 2246(1) ų, Z = 4. The crystal structure of the title compound reveals that the DACO ring is also folded up into the chair/boat configuration, which is consistent with the configuration in most of the transition metal complexes of DACO and its derivatives. The two imidazole pendants of the compound are in cis position with a dihedral angle of 16.0(4)°.     

Crystal and molecular structure of powerine: Methyl 10,17-dihydroxy-(16β,17β,20α)-yohimban-16-carboxylate

The methanol adduct of powerine [methyl 10,17-dihydroxy-(16,17,20)-yohimban-16-carboxylate], C₂₁H₂₆N₂O₄. CH₃ OH, crystallizes in the orthorhombic space groupP2₁2₁2₁ (no. 19) with cell dimensionsa = 8.558(3),b = 14.162(7),c = 16.993(7) Å. The crystal and molecular structure has been determined by X-ray diffraction analysis and refined using full-matrix least squares methods to a reliability index,R, of 0.090 with 1139 observed (F 2.5 _F ) intensities. With the configuration at C15 arbitrarily assigned those at the chiral centers C3-H, C16-CO₂Me, C17-OH and C20-H are respectively ,,,: theC-D ring junction istrans and that ofD-E iscis. All bond lengths and bond angles are normal.     

N-Arylmaleimide derivatives

Nine phenyl substituted N-phenylmaleimide monomers for photopolymerization studies have been characterized by x-ray crystallography. Structures for N-(2-t-butylphenyl)maleimide (1), P2₁/n, a = 10.197(3) Å, b = 11.904(4) Å, c = 10.496(5) Å, = 100.61(3)° N-(2-trifluoromethylphenyl)maleimide (2), P2₁/c, a = 11.763(8) Å, b = 10.699(9) Å, c = 8.284(5) Å, = 90.02(5)° N-(2,6-diisopropylphenyl)maleimide hemibenzene solvate (3), Pc, a = 16.747(6) Å, b = 8.552(3) Å, c = 12.899(4) Å, = 105.08(3)° N-(2,6-diisopropylphenyl) maleimide (unsolvated) (4), C2/c, a = 28.146(10) Å, b = 8.434(4) Å, c = 12.881(4) Å, = 92.20(4)° N-(2-bromo-3,5-bis(trifluoromethyl)phenyl) maleimide (5), P2₁/n, a = 8.7115(16) Å, b = 16.125(3) Å, c = 9.6707(19) Å, = 99.757(15)° N-(2-phenylphenyl)maleimide (6), P2₁/n, a = 8.519(4) Å, b = 13.742(5) Å, c = 11.147(4) Å, = 92.25(3)° N-(4-methoxyphenyl)maleimide (7), P2₁/n, a = 9.320(3) Å, b = 6.621(2) Å, c = 16.059(6) Å, = 99.58(3)° N-(2-trifluoromethylphenyl)-2-methylmaleimide (8), Fdd2, a = 43.362(12) Å, b = 8.202(2) Å, c = 12.720(4) Å and N-(2-trifluoromethylphenyl)-2-methanosuccinimide (9), Cc, a = 7.708(2) Å, b = 22.191(9) Å, c = 7.137(2) Å, = 115.76(2)° are described. Molecules with bulky 2-substituents show larger rotations between the mean phenyl and maleimide ring planes, and varying degrees of distortion to the imide group.     

Crystal structure of diethoxynitrobenzene-p-tert-butylcalix [4]arene⋅2(CH3)2C=O: Evidence of intra- and intermolecular CH/π interactions forced by crystal packing

Diethoxynitrobenzene-p-tert-butylcalix[4]arene2(CH₃)₂C=O crystallized in the monoclinic system, space group P2₁/c, with cell dimensions a = 16.1437(2) Å, b = 21.0292(2) Å, c = 18.9685(3) Å and = 110.308(1)°. The asymmetric unit consists of a diethoxynitrobenzene-p-tert-butylcalix[4]arene molecule and two solvated acetone molecules. Besides the usual CH/ interaction between p-tert-butylcalix[4]arene cavity and a solvated acetone, this structure shows the intra- and intermolecular CH/ interactions among a nitrobenzene ring, ethylene bridge of the ethoxynitrobenzene side chain and a solvated acetone molecule.     

Amino acid complexes of [Co(III) (trien)]+3

Seven ₂ complexes have been investigated and the structural parameters compared with literature values and molecular mechanics calculations. All ₂ compounds exhibit the (S,S,) or, (R,R,) configuration. Three of the ₂ complexes have monocoordinated amino acids or amino acid esters while the amino acid is chelated in the others. The Co–N bondtrans to the amino acid oxygen or a Cl^– varies significantly in length due to thetrans-effect. The chelate rings are twisted to minimize torsional interactions and the changes in conformation in the various structures can be modeled by molecular mechanics. In one complex the carbonyl groups of enantiomeric complexes are bridged by silver ions. In ₂[Co(trien)(C-formylglycine)]Cl₂ · H₂O the carbonyl oxygen of the chelated amino acid is protonated and the formyl group exists in the enol form.     

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 and molecular structure of (±)-1-phenyl-2-amino-1-propanol,C9H13NO

The crystal structure of (±)-phenylpropanolamine has been determined by single-crystal X-ray diffraction methods. The structure was solved by direct methods and refined by least-squares toR=0.055 andR _w=0.045 for 2000 reflections (I2 (I)). The molecule was found to adoptgauche geometry. Inter- and intramolecular N-HO and O-HN hydrogen bonds were observed in the crystal structure.     

The structural characterization of YbI2(DME)3

The preparation and structural characterization of [YbI₂(DME)₂] are reported. The complex crystallizes in the triclinic space group P 1¯: a = 13.0094 (10), b=14.504(3), c = 14.668 (3) Å, = 115.281(10) = 106.74(2), = 105.97(2)°. The metal center of the complex exhibits a distorted pentagonal bipyramidal coordination geometry which involves a rare example of a monodentate DME ligand.