Two stereoisomeric pentacyclic oxin­dole alkaloids from Uncaria tomentosa: uncarine C and uncarine E

The chloro­form solvate of uncarine C (pteropodine), (1′S,3R,4′aS,5′aS,10′aS)‐1,2,5′,5′a,7′,8′,10′,10′a‐octa­hydro‐1′‐methyl‐2‐oxospiro­[3H‐indole‐3,6′(4′aH)‐[1H]­pyrano­[3,4‐f]indolizine]‐4′‐carboxyl­ic acid methyl ester, C₂₁H₂₄N₂O₄·CHCl₃, has an absolute configuration with the spiro C atom in the R configuration. Its epimer at the spiro C atom, uncarine E (isopteropodine), (1′S,3S,4′aS,5′aS,10′aS)‐1,2,5′,5′a,7′,8′,10′,10′a‐octahydro‐1′‐methyl‐2‐oxospiro[3H‐indole‐3,6′(4′aH)‐[1H]pyrano[3,4‐f]indolizine]‐4′‐carboxylic acid methyl ester, C₂₁H₂₄N₂O₄, has Z′ = 3, with no solvent. Both form intermolecular hydrogen bonds involving only the ox­indole, with N?O distances in the range 2.759 (4)–2.894 (5) Å.     

The gossypol–cyclo­dodecanone (1/2) inclusion complex

Gossypol and cyclo­dodecanone crystallize at room temperature as an inclusion complex in a 1:2 molar ratio. This complex, viz. 1,1′,6,6′,7,7′‐hexa­hydroxy‐5,5′‐diiso­pro­pyl‐3,3′‐di­methyl‐2,2′‐bi­naphthalene‐8,8′‐di­carbox­aldehyde–cyclo­do­deca­none (1/2), C₃₀H₃₀O₈·2C₁₂H₂₂O, is unusual in that there is limited intermolecular hydrogen bonding within the structure. Each cyclo­dodecanone mol­ecule accepts a hydrogen bond from a gossypol mol­ecule, but there are no gossypol‐to‐gossypol hydrogen‐bond interactions. The gossypol mol­ecules form a framework structure enclosing channels, and the cyclo­dodecanone mol­ecules lie in these channels. In terms of the number of non‐H guest atoms, this is the largest gossypol inclusion complex reported to date.     

A synchrotron‐radiation study of the lactone form of rhodamine B at 120 K

The structure of the lactone form of rhod­amine B, 3,6‐bis­(diethyl­amino)‐1′,3′‐di­hydro­spiro­[xanthene‐9,3′‐isobenzo­furan]‐1′‐one, C₂₈H₃₀N₂O₃, has been determined at 120 K using synchrotron radiation at a wavelength of 0.496 Å. The structure contains two independent rhod­amine B mol­ecules with virtually identical geometry. The xanthene main planes of the mol­ecules are inclined at an angle of 41.6 (2)° to one another. Molecule 2 has a statistically disordered ethyl group, with 71% in one orientation and 29% in a second orientation. The lactone C—O bonds are 1.497 (1) and 1.495 (1) Å. There are no classical hydrogen bonds, but the structure is stabilized by two short C?O interactions. The crystals of the lactone form were produced by a novel hydro­thermal reaction.     

2′,4′‐Di­hydroxy‐3‐methoxy‐α,β‐di­hydro­chalcone and 2′,4‐di­hydroxy‐α,β‐di­hydro­chalcone: supramolecular structures formed by O—H⋯O,C—H⋯O and stacking interactions

The crystal structures of 2′,4′‐di­hydroxy‐3‐methoxy‐α,β‐di­hydro­chalcone, C₁₆H₁₆O₄, and 2′,4‐di­hydroxy‐α,β‐di­hydro­chalcone, C₁₅H₁₄O₃, have been determined. In both compounds, the structure consists of two nearly planar six‐membered aromatic rings connected by a propanal chain, which is bent in the methoxy compound and almost straight in the other compound. In the crystal structures, the molecular units of both compounds are linked by O—H⋯O hydrogen bonds to form infinite one‐dimensional chains. Hydro­gen bonds and C—H⋯O contacts in the crystal structures were studied by topological analysis of charge density based on Hartree–Fock calculations. Almost all of the investigated C—H⋯O contacts should be characterized as weak hydrogen bonds.     

Stereochemistry of two new polyfunctionalized gem‐dihalo­cyclo­propanes

The two new gem‐dihalogeno­cyclo­propanes (1′S,3R)‐3‐(2′,2′‐di­chloro‐1′‐methyl­cyclo­propyl)‐6‐oxoheptanoic acid, C₁₁H₁₆­Cl₂O₃, (2), and (1′S,3R)‐3‐(2′,2′‐di­bromo‐1′‐methyl­cyclo­propyl)‐6‐oxoheptanoic acid, C₁₁H₁₆Br₂O₃, (3), are isostructural. Both present two stereogenic centers at C1′ and C3. The absolute configuration was determined by X‐ray methods. The cyclo­propyl rings are unsymmetrical, the shortest bond being distal with respect to the alkyl‐substituted C atom.     

Hydrogen bonding and π–π stacking in methyl­aminium 4′,7‐dihydroxy­isoflavone‐3′‐sulfonate dihydrate and hexa­aqua­iron(II) bis­(4′,7‐diethoxy­isoflavone‐3′‐sulfonate) tetra­hydrate

In methyl­aminium 4′,7‐dihydroxy­isoflavone‐3′‐sulfonate dihydrate, CH₆N⁺·C₁₅H₉O₇S⁻·2H₂O, 11 hydrogen bonds exist between the methyl­aminium cations, the iso­flavone‐3′‐sulfonate anions and the solvent water mol­ecules. In hexa­aqua­iron(II) bis­(4′,7‐diethoxy­isoflavone‐3′‐sulfonate) tetra­hydrate, [Fe(H₂O)₆](C₁₉H₁₇O₇S)₂·4H₂O, 12 hydrogen bonds exist between the centrosymmetric [Fe(H₂O)₆]²⁺ cation, the isoflavone‐3′‐sulfonate anions and the solvent water mol­ecules. Additional π–π stacking inter­actions generate three‐dimensional supramolecular structures in both compounds.     

Two 2,2‐dihalo‐N‐(1‐phenyl­ethyl)­cyclo­propane‐1‐carbox­amides

The crystal structures of (1R,1′S)‐2′,2′‐di­chloro‐N‐(1‐phenyl­ethyl)­cyclo­propane‐1′‐carbox­amide, C₁₂H₁₃Cl₂NO, (I), and (1R,1′R)‐2′,2′‐di­fluoro‐N‐(1‐phenyl­ethyl)­cyclo­propane‐1′‐car­box­amide, C₁₂H₁₃F₂NO, (II), have been determined. Both crystals contain two independent mol­ecules with different conformations of the phenyl­ethyl groups. In the crystals of both compounds, the mol­ecules are linked together by N—H⃛O hydrogen bonds, thus forming chains in the a direction.     

Dimorphism in 3′‐amino­cyclo­hexane­spiro‐5′‐hydantoin

The title compound [systematic name: 1′‐amino­cyclo­hexane­spiro‐4′‐imidazole‐2′,5′(3′H,4′H)‐dione], C₈H₁₃N₃O₂, has been synthesized and was found to crystallize in two different structures, both monoclinic and both with the same P2₁/c space group. In the first structure, there are two mol­ecules in the asymmetric unit, one of which uses all of its hydrogen‐bond donors and acceptors and forms undulating layers, while the other forms chains propagating perpendicular to the layers. In the second structure, there is only one independent mol­ecule and the packing is based on a chain structure mediated by hydrogen bonding between the hydantoin moieties and further grouped into hydro­philic layers separated by layers of the hydro­phobic cyclo­hex­yl groups.     

Four cyclo­alkane­spiro‐4′‐imidazolidine‐2′,5′‐dithiones

The crystal structures of four cyclo­alkane­spiro‐4′‐imidazolidine‐2′,5′‐dithiones, namely cyclo­pentane­spiro‐4′‐imidazolidine‐2′,5′‐dithione {systematic name: 1,3‐diaza­spiro­[4.4]­nonane‐2,4‐dithione}, C₇H₁₀N₂S₂, cyclo­hexane­spiro‐4′‐imidazolidine‐2′,5′‐dithione {systematic name: 1,3‐diaza­spiro­[4.5]decane‐2,4‐dithione}, C₈H₁₂N₂S₂, cyclo­heptane­spiro‐4′‐imidazolidine‐2′,5′‐dithione {systematic name: 1,3‐diaza­spiro­[4.6]undecane‐2,4‐dithione}, C₉H₁₄N₂S₂, and cyclo­octane­spiro‐4′‐imidazolidine‐2′,5′‐dithione {systematic name: 1,3‐di­aza­spiro­[4.7]dodecane‐2,4‐dithione}, C₁₀H₁₆N₂S₂, have been determined. The three‐dimensional packing in all of the structures is based on closely similar chains, in which hydantoin moieties are linked through N—H⋯S hydrogen bonding. The size of the cyclo­alkane moiety influences the degree of its deformation. In the cyclo­octane compound, the cyclo­octane ring assumes both boat–chair and boat–boat conformations.     

Different nucleobase orientations in two cyclic 2′,3′‐phosphates of purine ribonucleosides: Et3NH(2′,3′‐cAMP) and Et3NH(2′,3′‐cGMP)·H2O

The crystal structures of triethyl­ammonium adenosine cyclic 2′,3′‐phosphate {systematic name: triethyl­ammonium 4‐(6‐amino­purin‐9‐yl)‐6‐hydroxy­methyl‐2‐oxido‐2‐oxoperhydro­furano[3,4‐c][1,3,2]dioxaphosphole}, Et₃NH(2′,3′‐cAMP) or C₆H₁₆N⁺·C₁₀H₁₁N₅O₆P⁻, (I), and guanosine cyclic 2′,3′‐phosphate monohydrate {systematic name: triethyl­ammonium 6‐hydroxy­methyl‐2‐oxido‐2‐oxo‐4‐(6‐oxo‐1,6‐dihydro­purin‐9‐yl)perhydro­furano[3,4‐c][1,3,2]dioxaphosphole monohydrate}, [Et₃NH(2′,3′‐cGMP)]·H₂O or C₆H₁₆N⁺·C₁₀H₁₁N₅O₇P⁻·H₂O, (II), reveal different nucleobase orientations, viz. anti in (I) and syn in (II). These are stabilized by different inter‐ and intra­molecular hydrogen bonds. The structures also exhibit different ribose ring puckering [₄E in (I) and ³T₂ in (II)] and slightly different 1,3,2‐dioxaphospho­lane ring conformations, viz. envelope in (I) and puckered in (II). Infinite ribbons of 2′,3′‐cAMP⁻ and helical chains of 2′,3′‐cGMP⁻ ions, both formed by O—H⋯O, N—H⋯X and C—H⋯X (X = O or N) hydrogen‐bond contacts, characterize (I) and (II), respectively.     

Hydro­gen‐bond networks in tris(4‐hydroxy­phenyl)­methane and its 1:1 molecular complex with 4,4′‐bi­pyridine

In tris(4‐hydroxy­phenyl)­methane (or 4,4′,4′′‐methane­triyl­tri­phenol), C₁₉H₁₆O₃, mol­ecules are connected by O—H⃛O hydrogen bonds [O⃛O = 2.662 (2) and 2.648 (2) Å] into two‐dimensional square networks that are twofold interpenetrated. In tris(4‐hydroxy­phenyl)­methane–4,4′‐bi­pyridine (1/1), C₁₉H₁₆O₃·C₁₀H₈N₂, trisphenol mol­ecules form rectangular networks via O—H⃛O [O⃛O = 2.694 (3) Å] and C—H⃛O [C⃛O = 3.384 (3) Å] hydrogen bonds. Bi­pyridine mol­ecules hydrogen bonded to phenol moieties [O⃛N = 2.622 (3) and 2.764 (3) Å] fill the voids to complete the structure.     

The one‐electron oxidation product of a metallocenyl‐terminated cyanine

The 1‐(2,3,4,5,1′,2′,3′,4′‐octa­methyl­ferrocen‐1‐yl)‐3‐(ruth­eno­cen­yl)­allylium cation readily undergoes one‐electron oxidation to a dication in which an octa­methyl­ferrocenium moiety is bridged by a vinyl­ene group to a [(η⁶‐fulvene)(η⁵‐cyclo­penta­dienyl)­ruthenium]⁺ moiety. In the title compound, 1‐(2,3,4,5,1′,2′,3′,4′‐octa­methyl­ferrocen‐1‐yl)‐3‐(ruth­eno­cen­ylidene)prop‐1‐enium(2+) bis­(tetra­fluoro­borate), [Fe­Ru­(C₅H₅)(C₉H₁₃)(C₁₇H₁₉)]­(BF₄)₂, the C—C bond lengths in the bridge (average for two independent mol­ecules) are, starting from the ipso octa­methyl­ferrocenium carbon and ending at the exo carbon of the coordinated fulvene, 1.455 (6), 1.344 (3) and 1.449 (8) Å, indicating a localized electronic structure.     

An intermediate in a new synthesis approach to β‐substituted β‐hydroxy­aspartame

The crystal and molecular structure of 1‐tert‐butyl 4‐ethyl (2′R,3′R,5′R,2S,3S)‐3‐bromo­methyl‐3‐hydroxy‐2‐[(2′‐hydroxy‐2′,6′,6′‐tri­methyl­bi­cyclo­[3.1.1]­hept‐3′‐yl­idene)­amino]­succinate, C₂₁H₃₄BrNO₆, is presented. This compound is an intermediate in the new synthetic route to β‐substituted β‐hydroxy­aspartates, which are blockers of glutamate transport.     

A new photochromic tetra­hydro­indolizine

The title compound, di­methyl 10b′‐(4‐fluoro­styryl)‐8′,9′‐di­methoxy‐4‐nitro‐5′,6′‐di­hydrospiro­[9H‐fluorene‐9,1′(10b′H)‐pyrrolo­[2,1‐a]­iso­quinoline]‐2′,3′‐di­carboxyl­ate, C₃₈H₃₁FN₂O₈, is a new photochromic tetra­hydro­indolizine. One of the C—C bonds at the spiro C atom is very long [1.630 (2) Å], thus explaining the photochromic behaviour.     

Bis(3‐amino­pyridine‐κN)(4,4′‐di­methyl‐2,2′‐bipyridine‐κ2N,N′)(per­chlorato‐κO)copper(II) per­chlorate

The title compound, [Cu(ClO₄)(C₅H₆N₂)₂(C₁₂H₁₂N₂)]ClO₄, was prepared by in situ partial ligand substitution between 3‐amino­pyridine and 4,4′‐dimethyl‐2,2′‐bipyridine at room temperature. The central copper(II) ion is five‐coordinated by one bidentate 4,4′‐dimethyl‐2,2′‐bipyridine mol­ecule, two monodentate pyridine‐coordinated 3‐amino­pyridine mol­ecules and one apical O atom from the perchlorate counter‐ion. Inter­molecular N—H⋯O and C—H⋯O hydrogen‐bonding inter­actions form a hydrogen‐bond‐sustained network.     

Tetra­allyl (2,2′‐bipyridyl)‐rac‐3,3,7,7‐tetra­methyl‐trans‐5‐palladatricyclo[4.1.0.02,4]­heptane‐1,2,4,6‐tetra­carboxyl­ate above and below the phase‐transition temperature of 194 K

The crystal structure of the title compound, (2,2′‐bipyridyl‐κ²N,N′)(tetra­allyl 3,3,3′,3′‐tetra­methyl‐1,1′‐bi­cyclo­propane‐1,1′,2,2′‐tetra­carboxyl­ato‐κ²C²,C^2′)­palladium(II), [Pd(C₂₆H₃₂­O₈)(C₁₀­H₈­N₂)], is disordered above 194 K. A doubling of the unit cell is observed on cooling. The structure at 143 K contains two ordered mol­ecules related by a pseudo‐translation vector of approximately (0.44,0.00,0.50) or a pseudo‐inversion center at approximately (0.22,0.00,0.25). Weak intermolecular C—H?O interactions are enhanced in the low‐temperature structure.     

Synthesis of spiro[indoline‐3,3′‐pyrrolizines] by 1,3‐dipolar reactions between isatins,l‐proline and electron‐deficient alkenes

Two spiro[indoline‐3,3′‐pyrrolizine] derivatives have been synthesized in good yield with high regio‐ and stereospecificity using one‐pot reactions between readily available starting materials, namely l ‐proline, substituted 1H‐indole‐2,3‐diones and electron‐deficient alkenes. The products have been fully characterized by elemental analysis, IR and NMR spectroscopy, mass spectrometry and crystal structure analysis. In (1′RS ,2′RS ,3SR ,7a′SR )‐2′‐benzoyl‐1‐hexyl‐2‐oxo‐1′,2′,5′,6′,7′,7a′‐hexahydrospiro[indoline‐3,3′‐pyrrolizine]‐1′‐carboxylic acid, C₂₈H₃₂N₂O₄, (I), the unsubstituted pyrrole ring and the reduced spiro‐fused pyrrole ring adopt half‐chair and envelope conformations, respectively, while in (1′RS ,2′RS ,3SR ,7a′SR )‐1′,2′‐bis(4‐chlorobenzoyl)‐5,7‐dichloro‐2‐oxo‐1′,2′,5′,6′,7′,7a′‐hexahydrospiro[indoline‐3,3′‐pyrrolizine], which crystallizes as a partial dichloromethane solvate, C₂₈H₂₀Cl₄N₂O₃·0.981CH₂Cl₂, (II), where the solvent component is disordered over three sets of atomic sites, these two rings adopt envelope and half‐chair conformations, respectively. Molecules of (I) are linked by an O—H…·O hydrogen bond to form cyclic R ₆⁶(48) hexamers of (S ₆) symmetry, which are further linked by two C—H…O hydrogen bonds to form a three‐dimensional framework structure. In compound (II), inversion‐related pairs of N—H…O hydrogen bonds link the spiro[indoline‐3,3′‐pyrrolizine] molecules into simple R ₂²(8) dimers.     

(±)‐6‐tert‐Butyl‐8‐hydroxymethyl‐2‐­phenyl‐4H‐1,3‐benzodioxin and 2,2,2′,2′,6,6′‐hexamethyl‐8,8′‐methylenebis(4H‐1,3‐benzodioxin)

Two compounds containing 1,3‐benzodioxin groups are reported, namely (±)‐6‐tert‐butyl‐8‐hydroxy­methyl‐2‐phenyl‐4H‐1,3‐benzodioxin, C₁₉H₂₂O₃, (I), and 2,2,2′,2′,6,6′‐hexamethyl‐8,8′‐methyl­enebis(4H‐1,3‐benzodioxin), C₂₃H₂₈O₄, (II).The hydroxy groups of neighbouring mol­ecules in (I) are hydrogen bonded to each other, giving rise to double‐row chains. The mol­ecule in (II) adopts a `butterfly' conformation, with the O atoms in distal positions. In both compounds, the dioxin rings are in distorted half‐chair conformations.     

2,4,6‐Tri­methyl­phenol

Crystals of the title compound, C₉H₁₂O, were formed as an unexpected by‐product during the recrystallization of (2R,3R)‐α,α,α′,α′‐tetramesityl‐1,4‐dioxa­spiro­[4,5]­decane‐2,3‐di­methanol from hexane/ethyl acetate (7:3). Strong hydrogen bonds between hydroxide groups connect the mol­ecules around one set of four symmetry‐equivalent 2₁ axes.     

An ion pair formed by protonated Fe(cp*py)2 and the octanuclear cluster U8Cl24O4(cp*py)2 [cp*py is tetramethyl‐5‐(2‐pyridyl)cyclopentadiene]

In bis­[1,1′,2,2′,3,3′,4,4′‐octa­methyl‐5‐(2‐pyridinio)‐5′‐(2‐pyri­dyl)­ferrocene] di‐μ₃‐chloro‐hexadeca‐μ₂‐chloro‐hexa­chloro­di‐μ₄‐oxo‐di‐μ₃‐oxo‐bis­[(η⁵,κN)‐1,2,3,4‐tetra­methyl‐5‐(2‐pyridyl)­cyclo­penta­dienyl]octauranium(IV) di­chloro­methane tetrasolvate, [Fe(C₁₄H₁₇N)(C₁₄H₁₆N)]₂[U₈Cl₂₄O₄(C₁₄H₁₆N)₂]·4CH₂Cl₂, (I), two protonated Fe(cp*py)₂ units [cp*py is tetra­methyl‐5‐(2‐pyridyl)­cyclo­penta­diene] form an ion pair with the dianionic centrosymmetric cluster U₈Cl₂₄O₄(cp*py)₂. The latter is the highest nuclearity assemblage in the chemistry of uranium (non‐uranyl) compounds reported to date.