Crystal and molecular structure of N-methyl-8-fluoroquinolinium chloride,C10H9NFCl·H2O

The crystal structure ofN-methyl-8-fluoroquinolinium chloride was determined by single crystal X-ray diffraction with refinement by full-matrix least-squares techniques. The crystals belong to theP2₁/n space group with unit cell parametersa=6.938(3),b=7.855(4),c=18.592(14) Å, and =94.72(4)°. The calculated and observed densities are 1.415(6) and 1.421 g cm^–3, respectively. Isotropie refinement of hydrogens and anisotropic refinement of all other atoms with 1040 unique reflections havingI>3(I) converged withR ₁=0.055 andR ₂=0.060. Steric interactions between the fluorine and the methyl group are evident from the structural data, but the planarity of the quinolinium ring is not significantly distorted.     

Partial synthesis of 23-hydroxyursolic acid isolated from medicinal plants of the Rubiaceae family

23-Hydroxyursolic acid (2), previously isolated from medicinal plants of the Rubiaceae family, was synthesized in ten steps via methyl 23-hydroxy-3-oxours-12-en-28-oate (5) from commercially available ursolic acid (6).     

Potential DNA bis-intercalating agents: Synthesis and antitumor activity of novel,conformationally restricted bis(9-aminoacridines)

A series of bis(9-aminoacridines) bridged by conformationally restricted tethers was synthesized and evaluated against L1210 in vitro. Several of these compounds were found to be highly active in this test system, with ID₅₀ values below 10^?7 M. CPK molecular models suggest that this antitumor activity can be correlated to the ability of these bis(9-aminoacridines) to form bis-intercalative complexes with DNA.     

Enantioseparation and absolute configuration of the atropisomers of a naturally produced hexahalogenated 1,1′-dimethyl-2,2′-bipyrrole

Hexahalogenated 1,1′-dimethyl-2,2′-bipyrroles (HDBPs) are a group of marine halogenated natural products (HNPs) that have been detected in environmental samples from all over the world. The most frequently described congener is the 5,5′-dichloro-1,1′-dimethyl-3,3′,4,4′-tetrabromo-2,2′-bipyrrole (DBP-Br₄Cl₂, BC-10). This compound is axially chiral, by virtue of hindered rotation about the interannular pyrrole–pyrrole bond forming stable atropisomers. This effect was proven by the separation of synthesized racemic DBP-Br₄Cl₂ by enantioselective high performance liquid chromatography (HPLC). Pure enantiomers were isolated using enantioselective HPLC. Crystallization led to white crystals studied by X-ray analyses to determine the absolute configuration. Subsequent polarimetric measurements verified the first eluting enantiomer on HPLC as R_a-(+)-DBP-Br₄Cl₂ and the second as S_a-(−)-DBP-Br₄Cl₂. We also investigated the gas chromatography (GC) enantioseparation of DBP-Br₄Cl₂. However, too high temperatures in the injector port led to partial racemization at temperatures >150 °C. GC coupled to mass spectrometry was used to study DBP-Br₄Cl₂ in marine mammal samples. All samples contained both atropisomers of the natural product DBP-Br₄Cl₂ with enrichment of the levo (−) enantiomer. This led to the assumption that both enantiomers of DBP-Br₄Cl₂ were already produced in the environment.     

The fused heterocycle 2‐benzyl‐3‐methyl‐1‐phenyl‐4‐phenyl­sulfonyl‐2H,4H‐pyrrolo­[3,4‐b]­indole

Crystal structure determination of the title mol­ecule, C₃₀H₂₄N₂O₂S, reveals that the pyrrole ring in this fused heterocycle, although presumably strained and reactive in cyclo­addition reactions, does not differ appreciably from N‐methyl­pyrrole except for a shorter C—C single bond [1.409 (4) Å] in the pyrrole ring.