Stereoselective synthesis of (26R)-26-hydroxydiosgenin and its effect on the regulation of rat ovarian function.

The stereoselective cyclization of a C-16 acetylated 22,26-dioxocholestene derivative to give the spirostane E and F rings, under alkaline conditions, yields exclusively the (26R)-26-hydroxydiosgenin. Both experimental and computational data support the formation of a single diastereoisomer. The effect of diosgenin and (26R)-26-hydroxydiosgenin on rat ovary is also investigated.

Mesoscale Assembly of Bisteroidal Esters from Terephthalic Acid.

A new series of bisteroidal esters was synthesized using a spacer group, sterols and sapogenins as substrates. Steroidal dimers were prepared in high yields employing diesters of terephthalic acid as linkages at the 3ß, 3'ß steroidal positions. In all attempts to crystallize bisteroids, it was observed that the compounds tended to self-organize in solution, which was detected when employing various solvent systems. The non-covalent interactions (van der Waals) of the steroidal moieties of this series of symmetrical bisteroids, the polarity of the solvents systems, and the different solubilities of the bisteroid aggregates, indeed induce the molecules to self-assemble into supramolecular structures with well-defined organization. Our results show that the self-assembled structures for the bisteroidal derivatives depend on the solvent system used: with hexane/EtOAc, membrane-shaped structures were obtained, while pure EtOAc afforded strand-shaped arrangements. In the CHCl3/CH3OH system, thin strands were formed, since van der Waals interactions are lowered in this system, as a consequence of the increased solubility of the bisteroids in CHCl3. Based on the characterization by SEM and XRD, we show evidence that the phenomenon of self-assembly of bisteroids occurs presenting different morphologies depending on the solvent used. The new steroidal dimer derivatives were characterized by NMR, TGA, DSC, SEM, and XRD. Finally, the molecular structure of one bisteroid was confirmed by single-crystal X-ray analysis.

Coumarin Derivative Directly Coordinated to Lanthanides Acts as an Excellent Antenna for UV-Vis and Near-IR Emission.

A chelating coumarin-derived ligand sensitizes all emitting lanthanide ions in the solid state and gives high absolute quantum yields for ethanol solutions of complexes of Sm, Eu, Tb, and Dy, above 20% for the last two. Crystal structures of these four complexes are [Ln(Cum)3(H2O)(X)]·X where X = MeOH or EtOH.

Clarivate Analytics: Continued Omnia vanitas Impact Factor Culture.

This opinion paper takes aim at an error made recently by Clarivate Analytics in which it sent out an email that congratulated academics for becoming exclusive members of academia's most cited elite, the Highly Cited Researchers (HCRs). However, that email was sent out to an undisclosed number of non-HCRs, who were offered an apology shortly after, through a bulk mail, which tried to down-play the importance of the error, all the while praising the true HCRs. When Clarivate Analytics senior management was contacted, the company declined to offer an indication of the number of academics who had been contacted and erroneously awarded the HCR status. We believe that this regrettable blunder, together with the opacity offered by the company, fortify the corporate attitude about the value of the journal impact factor (JIF), and what it represents, namely a marketing tool that is falsely used to equate citations with quality, worth, or influence. The continued commercialization of metrics such as the JIF is at the heart of their use to assess the "quality" of a researcher, their work, or a journal, and contributes to a great extent to driving scientific activities towards a futile endeavor.

Pelanserin: 3-[3-(4-phenyl-piperazin-1-yl)prop-yl]quinazoline-2,4(1H,3H)-dione.

The title compound, C21H24N4O2, is a potent serotonin 5-HT2 and α1-adrenoceptor antagonist. The n-propyl chain links the quinazolinedione heterocycle and the phenyl-piperazine group in which the benzene ring is equatorially located and the piperazine ring has the expected chair conformation. The dihedral angle between the planes of the benzene ring and the quinazolinedione ring system is 74.1 (1)°. In the crystal, mol-ecules form centrosymmetric dimers through R 2 (2)(8) hydrogen-bonded rings involving the amine and one carbonyl group of the quinazolinedione moiety. These dimers are extended into chains extending along the a-axis direction through expanded centrosymmetric cyclic C-H⋯O associations involving the second carbonyl group, giving R 2 (2)(20) and R 1 (2)(7) motifs.

2,5-Bis{[(-)-(S)-1-(4-bromo-phen-yl)eth-yl]imino-meth-yl}thio-phene.

The title compound, C22H20Br2N2S, was synthesized under solvent-free conditions. The mol-ecule shows crystallographic C 2 symmetry, with the S atom of the central thio-phene ring lying on a twofold rotation axis. Furthermore, as a consequence of the (S,S) stereochemistry, the mol-ecule has a twisted conformation. The dihedral angle between the thio-phene and benzene rings is 72.7 (2)° and that between the two benzene rings is 55.9 (2)°. In the crystal, mol-ecules are arranged in a chevron-like pattern, without any significant inter-molecular inter-actions.

Chlorido-(2-{(2-hy-droxy-eth-yl)[tris-(hy-droxy-meth-yl)meth-yl]amino}-ethano-lato-κ5 N,O,O',O'',O''')copper(II).

The title complex, [Cu(C8H18NO5)Cl] or [Cu(H4bis-tris-)Cl], was obtained starting from the previously reported [Cu(H5bis-tris-)Cl]Cl compound. The deprotonation of the amino-polyol ligand H5bis-tris {[bis-(2-hy-droxy-eth-yl)amino]-tris-(hy-droxy-meth-yl)methane, C8H19NO5} promotes the formation of a very strong O-H⋯O inter-molecular hydrogen bond, characterized by an H⋯O separation of 1.553 (19) Šand an O-H⋯O angle of 178 (4)°. The remaining hy-droxy groups are also engaged in hydrogen bonds, forming R 2 2(8), R 4 4(16), R 4 4(20) and R 4 4(22) ring motifs, which stabilize the triperiodic supra-molecular network.

trans-Di-chlorido-bis-(secnidazole-κN 3)copper(II).

The use of acetic acid (HOAc) in a reaction between CuCl2·2H2O and secnid-azole, an active pharmaceutical ingredient useful in the treatment against a variety of anaerobic Gram-positive and Gram-negative bacteria, affords the title complex, [CuCl2(C7H11N3O3)2]. This compound was previously synthesized using ethanol as solvent, although its crystal structure was not reported [Betanzos-Lara et al. (2013 ▸). Inorg. Chim. Acta, 397, 94-100]. In the mol-ecular complex, the Cu2+ cation is situated at an inversion centre and displays a square-planar coordination environment. There is a hydrogen-bonded framework based on inter-molecular O-H⋯Cl inter-actions, characterized by H⋯Cl separations of 2.28 (4) Šand O-H⋯Cl angles of 175 (3)°. The resulting supra-molecular network is based on R2 2 (18) ring motifs, forming chains in the [010] direction.

Methyl N-{(1R)-2-[(meth-oxy-carbon-yl)-oxy]-1-phenyleth-yl}carbamate.

The title mol-ecule, C12H15NO5, is a methyl carbamate derivative obtained by reacting (R)-2-phenyl-glycinol and methyl chloro-formate, with calcium hydroxide as heterogeneous catalyst. Supra-molecular chains are formed in the [100] direction, based on N-H⋯O hydrogen bonds between the amide and carboxyl-ate groups. These chains weakly inter-act in the crystal, and the phenyl rings do not display significant π-π inter-actions.

4-Hy-droxy-1,1'-bis-[(S)-1-phenyl-eth-yl]-5,5',6,6'-tetra-hydro-3,4'-bipyridine-2,2'(1H,1'H)-dione.

The title bis-piperidine, C26H28N2O3, was unexpectedly obtained via a dimerization mechanism promoted by acetic acid when performing the Dieckmann cyclization of a chiral amido ester. The S,S configuration was assigned by reference to the enanti-omerically pure starting material. In the mol-ecule, two core heterocycles are linked by a σ bond. One ring includes a keto-enol group, while the other presents an enone functionality. Both rings present a conformation inter-mediate between envelope and screw-boat, and the dihedral angle between the mean planes passing through the rings [48.9 (1)°] is large enough to avoid hindrance between ring substituents. The enol tautomeric form in one ring favors the formation of strong inter-molecular O-H⋯O=C hydrogen bonds. The resulting one-dimensional supra-molecular structure features single-stranded helices running along the 21 screw axis parallel to [100].

2,5-Bis{[(-)-(S)-1-(4-methyl-phen-yl)eth-yl]imino-meth-yl}thio-phene.

The title chiral bis-aldimine, C24H26N2S, was synthesized using a solvent-free Schiff condensation. The mol-ecule displays crystallographic C 2 symmetry, with the S atom lying on the twofold axis parallel to [100]. As a consequence of the (S,S) stereochemistry, the tolyl groups are oriented towards opposite faces of the thiophene core, giving a twisted conformation for the whole mol-ecule. Mol-ecules are arranged in the crystal in a herringbone-like pattern, without any significant inter-molecular contacts.

N,N'-Bis(2-amino-benz-yl)ethane-1,2-diaminium dinitrate.

In the title salt, C16H24N4 (2+)·2NO3 (-), both the cation and anion are placed in general positions, although the cation displays non-crystallographic inversion symmetry, with the aliphatic chain extended in an all-trans conformation. The benzene rings are almost parallel, with a dihedral angle between their mean planes of 3.3 (6)°. The nitrate ions are placed in the vicinity of the protonated amine groups, forming efficient N-H⋯O inter-ion hydrogen bonds. Each nitrate ion in the asymmetric unit bridges two symmetry-related cations, forming an R 4 (4)(18) ring, a common motif in organic ammonium nitrate salts. This results in the formation of chains along [010] with alternating cations and anions. The neutral amine groups are involved in slightly weaker N-H⋯O hydrogen bonds with the nitrate O atoms, and there are also a number of C-H⋯O hydrogen bonds present. The resulting supra-molecular structure is based on a two-dimensional network extending in the ab plane.

Cyclo-hexane plastic phase I: single-crystal diffraction images and new structural model.

The plastic phase of cyclohexane (polymorph I) was studied by Kahn and co-workers, without achieving a satisfactory determination of the atomic coord-inates [Kahn et al. (1973). Acta Cryst. B29, 131-138]. The positions of the C atoms cannot be determined directly as a consequence of the disorder in a high-symmetry space group, an inherent feature of plastic materials. Given this situation, the building of a polyhedron describing the disorder was the main tool for determining the molecular structure in the present work. Based on the shape of reflections {111}, {200} and {113} in space group Fm 3 m, we assumed that cyclohexane is disordered through the action of rotation group 432. The polyhedral cluster of disordered molecules is then a rhombic dodecahedron centred on the nodes of an fcc Bravais lattice. The vertices of this polyhedron are the positions of C atoms for the cyclohexane molecule, which is disordered over 24 positions. With such a model, the asymmetric unit is reduced to two C atoms placed on special positions, and an acceptable fit between the observed and calculated structure factors is obtained.

Meloxicam hydro-chloride.

The title salt, C14H14N3O4S2 +·Cl- [systematic name: 2-(4-hy-droxy-2-methyl-1,1-dioxo-1,2-benzo-thia-zine-3-amido)-5-methyl-1,3-thia-zol-3-ium chloride] is the hydro-chloride derivative of meloxicam, a drug used to treat pain and inflammation in rheumatic disorders and osteoarthritis. Although its mol-ecular structure is similar to that previously reported for the hydro-bromide analogue, both salts are not isomorphous. Different crystal structures originate from a conformational modification, arising from a degree of rotational freedom for the thia-zolium ring in the cations. By taking as a reference the conformation of meloxicam, the thia-zolium ring is twisted by 10.96 and -16.70° in the hydro-chloride and hydro-bromide salts, while the 1,2-benzo-thia-zine core is a rigid scaffold. This behaviour could explain why meloxicam is a polymorphous compound.

2-[3-(1H-Benzimidazol-2-yl)prop-yl]-1H-benzimidazol-3-ium 3,4,5-tri-hydroxy-benzoate-1,3-bis-(1H-benzimidazol-2-yl)propane-ethyl acetate (2/1/2.94): co-crystallization between a salt, a neutral mol-ecule and a solvent.

The chemical formula of the title compound, 2C17H17N4 +·2C7H5O5 -·C17H16N4·2.94C4H8O2, was established by X-ray diffraction of a single-crystal obtained by reacting 1,3-bis-(benzimidazol-2-yl)propane (L) and gallic acid (HGal) in ethyl acetate. The mol-ecular structure can be described as a salt (HL)+(Gal)- co-crystallized with a mol-ecule L, with a stoichiometric relation of 2:1. Moreover, large voids in the crystal are filled with ethyl acetate, the amount of which was estimated by using a solvent mask during structure refinement, affording the chemical formula (HL +·Gal-)2·L·(C4H8O2)2.94. The arrangement of components in the crystal is driven by O-H⋯O, N-H⋯O and O-H⋯N hydrogen bonds rather than by π-π or C-H⋯π inter-actions. In the crystal, mol-ecules and ions shape the boundary of cylindrical tunnels parallel to [100] via R (rings) and D (discrete) supra-molecular motifs. These voids, which account for about 28% of the unit-cell volume, contain disordered solvent mol-ecules.

(23R,231 S,25S)-231,26-Ep-oxy-23-ethyl-furost-20(22)-en-3ß-ol.

The title compound, C29H46O3, is a steroid synthesized through a rearrangement of a sarsasapogenin derivative in acidic medium. The newly formed ring F is a tetra-hydro-2H-pyran heterocycle substituted by two methyl groups placed in equatorial positions. This ring displays a chair conformation, while di-hydro-furan ring E, to which it is bonded, has an envelope conformation. The mol-ecules are associated by weak O-H⋯O hydrogen bonds to form chains running in the [101] direction in the crystal.

1,4-Phenyl-ene diallyl bis-(carbonate).

The title mol-ecule, C14H14O6, is based on a benzene core di-substituted by allyl carbonate groups in the para positions. The mol-ecule is placed on an inversion centre, and the substituents are twisted with respect to the central benzene ring plane. The crystal structure does not include significant inter-molecular inter-actions other than weak C-H⋯O contacts between CH groups in the benzene ring and carbonate O atoms.

Synthesis and topology analysis of chlorido-triphen-yl(triphenyl phosphate-κO)tin(IV).

The title SnIV complex, [Sn(C6H5)3Cl(C18H15O4P)], is a formal adduct between triphenyl phosphate (PhO)3P=O and the stannane derivative chlorido-tri-phenyl-tin, SnPh3Cl. The structure refinement reveals that this mol-ecule displays the largest Sn-O bond length for compounds including the X=O→SnPh3Cl fragment (X = P, S, C, or V), 2.6644 (17) Å. However, an AIM topology analysis based on the wavefunction calculated from the refined X-ray structure shows the presence of a bond critical point (3,-1), lying on the inter-basin surface separating the coordinated phosphate O atom and the Sn atom. This study thus shows that an actual polar covalent bond is formed between (PhO)3P=O and SnPh3Cl moieties.

9-(Dicyano-methyl-idene)fluorene-tetra-thia-fulvalene (1/1).

The title compound, C(16)H(8)N(2)·C(6)H(4)S(4), crystallizes with the fluorene derivative placed in a general position and two half tetra-thia-fulvalene (TTF) mol-ecules, each completed to a whole mol-ecule through an inversion center. The fluorene ring system is virtually planar (r.m.s. deviation from the mean plane = 0.027 Å) and the dicyano group is twisted from the fluorene plane by only 3.85 (12)°. The TTF mol-ecules are also planar, and their central C=C bond lengths [1.351 (8) and 1.324 (7) Å] compare well with the same bond length in neutral TTF (ca 1.35 Å). These features indicate that no charge transfer occurs between mol-ecules in the crystal; the compound should thus be considered a cocrystal rather than an organic complex. This is confirmed by the crystal structure, in which no significant stacking inter-actions are observed between mol-ecules.

Westphalen's diol diacetate: 19(10→5)-abeo-5ß-cholest-9-ene-3ß,6ß-diyl diacetate.

THE STRUCTURE OF THE TITLE STEROID [ALTERNATIVE NAME: 3ß,6ß-diacet-oxy-5ß-methyl-19-norcholest-9(10)-ene], C31H50O4, confirms the generally accepted mechanism for the rearrangement of a cholestan-5α-ol derivative reported a century ago by Westphalen. The methyl group at position 10 of the starting material migrates to position 5 in the steroidal nucleus, while a Δ(9) bond is formed, as indicated by the C=C bond length of 1.347 (4) Å. The methyl transposition leaves the 5R configuration unchanged, with the methyl oriented towards the ß face. During the rearrangement, the steroidal B ring experiences a conformational distortion from chair to envelope with the C atom at position 6 as the flap. In the title structure, the isopropyl group of the side chain is disordered over two positions, with occupancies of 0.733 (10) and 0.267 (10). The carbonyl O atom in the acetyl group at C3 is also disordered with an occupancy ratio of 0.62 (4):0.38 (4).