Volume 60, Issue 2

Low-temperature single-crystal X-ray structures of the following 4-X-benzenesulfonamides have been studied in order to compare the effects of the 4-substituents on the molecular packings: X = F (1, orthorhombic, Pbca, Z′ = 1, structure previously reported), X = Cl (2, monoclinic, P2 1 /n, Z′ = 1), X = Br (3, isostructural with 2), X = Me (4, isomorphous with 2 and 3, room-temperature structure previously reported, accurate redetermination in this work), X = I (5, monoclinic, Pc, Z′ = 2 molecules with markedly different conformations). As a common feature, the five structures display molecular layers comprising an internal polar lamella of H 2 NSO 2 groups engaged in N-H···O hydrogen bonding, and hydrophobic peripheral regions consisting of the 4-X-substituted phenyl rings. Whereas each molecule in 1 - 4 is linked to four adjacent congeners by ordinary two-centre hydrogen bonds, the sterically demanding iodo substituent in 5 causes all N-H···O interactions to split up into longer N-H(···O) 2 three-centre bonds that are used to connect each molecule to six adjacent molecules. Important packing differences between 1 and the other structures appear to emanate from the high electronegativity of fluorine. In 2- 5, the polar lamellae are approximately planar, and the aromatic groups protrude obliquely (2 - 4) or vertically (5) from the lamellae to form translationgenerated parallel stacks separated by broad voids. Contiguous layers are packed via stack-void interlocking, thus creating high packing density and, concomitantly for 2, 3 and 5, interlayer halogen bonds of the type Cl···O, Br···O or I···N, respectively; none of the four structures exhibits π···π stacking interactions between aromatic rings or short halogen-halogen contacts. This simple packing architecture does not hold in the case of 1. Here, the polar lamella adopts a zigzag profile with acute angles of ca. 60°, allowing high packing density to be achieved by intralayer π···π stacking between parallel rows of geometrically convergent aryl rings. The electronegative fluorine atoms, efficiently shielded from the polar lamellae, are segregated into the regions between adjacent layers and form short F···F interlayer contacts about crystallographic centres of inversion.

The volume changes of lithium and sodium under pressure are discussed with respect to the packing density of the atoms and their valence. In densely packed Li I (bcc), Li II (fcc), and Li III (α-Hg type), valence increases from 1 at ≈ 5 GPa to ≈ 2.5 at 40 GPa. The maximum valence 3 is attained in Li IV (body-centered cubic, 16 atoms per cell, packing density q = 0.965) at 47 GPa. In densely packed Na I (bcc) a linear increase of valence from 1 at ≈ 10 GPa to 2.9 at 65 GPa is found which continues in Na II (fcc) up to 4.1 at 103 GPa.

Condensation of 2-hydroxy-3-methoxybenzaldehyde with m-phenylenediamine (1,3-diaminobenzene) (m-pda) gives the ligand [N,N′-bis(2-hydroxy-3-methoxybenzylidene)-1,3-diaminobenzene] which reacts with cupric acetate to give the complex [Cu 2 (L-m-pda) 2 ]·2H 2 O, [L = 2-hydroxy-3- methoxybenzaldehyde)]. The molecular structure of the complex [Cu 2 (L-m-pda) 2 ]·2H 2 O has been determined by single-crystal X-ray analysis. (C 44 H 40 Cu 2 N 4 O 8 )·2H 2 O, triclinic, space group P1̄. Two [Cu(L-m-pda)] fragments, related by an inversion center, are connected by m-phenylene groups to form a binuclear unit. The coordination geometry around each copper(II) can be described as a distorted tetrahedron formed by the N 2 O 2 donor set of the Schiff base ligands. The intramolecular Cu···Cu separation is 7.401(6) Å. The magnetic susceptibility of the complex in the 5 - 301 K temperature range can be rationalized by the parameters J = −0.4 cm −1 and g = 2.17. This indicates a weak intramolecular antiferromagnetic interaction. Extended Hückel molecular orbital (EHMO) calculations have been performed in order to gain insight into the molecular orbitals that participate in the super-exchange pathway.

1:1 and 1:2 lead(II) complexes with 2,9-dimethyl-1,10-phenanthroline (Dmphen), {[Pb(Dmphen)(NO 3 ) n ] and [Pb(Dmphen) 2 (ClO 4 ) 2 ]} have been synthesized and characterized by CHN elemental analysis, IR, 1 H NMR, 13 C NMR and 207 Pb NMR spectroscopy. The structure of these complexes was confirmed by X-ray crystallography. The single crystal X-ray data of [Pb(Dmphen)(NO3)n] show the complex to be polymeric and the Pb atom to have an unsymmetrical eight-coordinate geometry, the coordination being holodirected, whereas the [Pb(Dmphen) 2 (ClO 4 ) 2 ] complex is monomeric and the Pb atom has an unsymmetrical eight-coordinate geometry with the coordination hemidirected.

The reactions of bis(2,2,6,6-tetramethylpiperidino)aluminum bromide (tmp 2 AlBr) with Me 3 SiN 3 or Me 3 SiCN lead to trimeric tmp 2 AlN 3 and tmp 2 AlCN, respectively, while the reaction with Me 3 SiOCN produces the bicyclic compound [tmpCON(SiMe 3 ) 2 ] 2′ , 3. Similarly, di(tertbutyl) aluminum bromide reacts with Me 3 SiCN to give tetrameric (Me 3 C) 2 AlCN, 4. The compounds (Me 3 C) 2 AlN 3 and (Me 3 C) 2 AlOCN, obtained as oily products, have tetracoordinated Al atoms as shown by NMR spectroscopy, but the degree of oligomerization has not been determined.

2-(3’-Hydroxypropyl)benzimidazolium (Hhpb) hexa- and tetrachloroplatinate (C 10 H 13 N 2 O) 2 ·[PtCl 6 ] 1 and (C 10 H 13 N 2 O) 2 ·[PtCl 4 ] 2 were synthesized and their crystal structures determined. Compound 1 is monoclinic, space group P2 1 /n, a = 8.800(1), b = 14.389(2), c = 10.264(2) Å, β = 98.540(10)°, V = 1285.3(3) Å 3 , Z = 2 and Dc = 1.959 g cm −3 . Compound 2 is triclinic, space group P1̄, a=7.8480(10), b=9.0460(10), c=9.6980(10) Å ,α =65.420(10), β =68.810(10), γ = 76.770(1)°,V =581.26(4) Å 3 , Z =1 and Dc =1.969 g cm −3 . In both compounds, the Pt atoms reside at a centre of inversion. Compounds 1 and 2 are comprised of 2-(3’-hydroxypropyl)benzimidazolium (Hhpb) + : (C 10 H 12 N 2 O) + and [PtCl 6 ] 2− and [PtCl 4 ] 2− ions, respectively, linked by intermolecular hydrogen bonds N...Cl [range from 3.428(3) to 3.584(4) Å ], N···O [2.769(5) Å ] and O···Cl [3.338(4) and 3.321(3) Å ] for 1, and N···Cl [3.162(7) Å ], N···O [2.749(8) Å ] and O···Cl [3.289(6) Å ] for 2.

MeSO 2 CH 2 CN shows considerable C-H acidity at its methylene group. Through lithiation followed by reaction with (Ph 3 P)AuCl it can therefore be readily converted into the dinuclear, geminally substituted product MeSO 2 C[Au(PPh 3 )] 2 CN. With an excess of aurating reagents, a third [(Ph 3 P)Au] group becomes N-bonded to the nitrile unit to give an ionic trinuclear compound {MeSO 2 C[Au(PPh 3 )] 2 CNAu(PPh 3 )}+BF 4 − . The same product is obtained by direct reaction of MeSO 2 CH 2 CN with [(Ph 3 P)Au]BF 4 . The crystal structures of the two products have been determined. The diaurated sulfone parts of the molecule and the cation are virtually superimposible. Small Au-C-Au angles and short Au-Au contacts suggest significant aurophilic interactions (“Aframe” structures). The small -C≡N-Au angle of 165.6(5)° in the cation indicates that the strong [(Ph 3 P)Au] + acceptor causes substantial changes in the bonding of the nitrile group. Dilithiation of 1,3-dithiane-S,S’-tetroxide followed by reaction with 2 equivalents of (Ph 3 P)AuCl affords the geminally diaurated compound CH 2 (CH 2 SO 2 ) 2 C[Au(PPh 3 )] 2 .

Cobalt orotate trihydrate, [Co(C 5 N 2 O 4 H 2 )]·3H 2 O, has been synthesized and its crystal structure determined. The title compound crystallizes in the orthorhombic space group P2 1 2 1 2 1 (no. 19) with a = 771.5(2), b = 788.9(7), c = 1470.4(2) pm, and Z = 4. Bridging orotate anions coordinate in a mono- and bidentate manner to the Co atom resulting in infinite chains of alternating Co(II) cations and orotate (OrH 2− ) anions parallel to the c axis. The distorted octahedral Co coordination geometry is completed by three H 2 molecules. The FT-Raman and FT-IR spectra of the crystalline compound have been recorded and an assignment of the vibrational modes is proposed. The thermal behavior (TG) was investigated.

Tetramesityldibismuthane is obtained by the reaction of Mes 2 BiCl (Mes = 2,4,6-(CH 3 ) 3 C 6 H 2 ) and LiEH 4 (E = B, Al) with intermediate formation of Mes 2 BiH. Crystals of Mes 4 Bi 2 consist of centrosymmetric tetramesityldibismuthane molecules in the trans conformation. The value of the Bi-Bi bond length is 3.087(3) Å .

From the Streptomyces spp. 815 and GW4184, four new 4-juglon-2-ylbutyric acid derivatives, the juglomycins G - J (3a, 4a, 4c, 5c), have been isolated and characterised. The structures were derived from the 1D and 2D NMR data and mass spectra and confirmed by comparison with structurally related compounds. The absolute configuration was deduced from the CD spectra. The new natural products exhibited weak antibacterial activity similar to juglomycin A (5a).

Novel juglomycin derivatives with a C 28 skeleton were isolated from the Streptomyces strains 815 and GW4184. Juglorescein (1a) and juglocombin A (2a) and B (3a) are C,C dimers of juglomycin C (10) with a five membered ring between the two monomeric moieties. In the juglochromans A-D (4a, 5a, 6a, 6c), two juglomycin C (10) units are connected by C,C and C,O bonds forming a central isochroman or a chroman system. The structures of the new natural products were elucidated by detailed spectra analyses, by comparison of the NMR data with those of related compounds and by biosynthetic considerations. The new natural products were antimicrobially inactive.

The ethanolic and acetone extracts of the whole plant of Elephantopus scaber were found to contain ethyl hexadecanoate, ethyl-9,12-octadecadienoate, ethyl-(Z)-9-octadecenoate, ethyl octadecanoate, lupeol, stigmasterol, stigmasterol glucoside, deoxyelephantopin (1) and two new germacranolide sesquiterpene lactones named 17,19-dihydrodeoxyelephantopin (2) and iso-17,19- dihydrodeoxyelephantopin (3) whose stereostructures were determined by spectroscopic methods, comparison with reported data and single-crystal X-ray analysis.

Roots of ginseng plants have been extracted with liquid ammonia or methanol/water (60:40 v/v). The extracts were characterized by means of a gradient HPLC/MS method and the results were compared with each other. The ginsenosides Rb 1 , Rb 2 , Rc, Rd, Re, Rf, Rg 1 and Ro including the malonyl ginsenosides m-Rb 1 , m-Rb 2 , m-Rc and m-Rd could be identified. Contrary to previous reports suggesting that during the extraction with liquid ammonia malonyl ginsenosides are totally converted to neutral ginsenosides, it could now be demonstrated by use of mass spectrometry that even after an extraction time of 4 h malonyl ginsenosides can be detected. However, the amount of malonyl ginsenosides was reduced by about one order of magnitude. The neutral ginsenosides were not changed by liquid ammonia. The mass spectrometric detection has been performed by use of the quasi-molecule ion [M+Na] + and some specific fragment ions.

Nine phenylethanoid glycosides were isolated from Buddleia lindleyana. On the basis of spectral analyses, their structures were elucidated to be acteoside (1), echinacoside (2), citanoside A (3), leucosceptoside A (4), leucosceptoside B (5), pedicularioside A (6), isoacteoside (7), arenariside (8), and a new compound named buddleoside A (9). The eight known compounds were isolated from this plant for the first time. The neuroprotective effects of compounds 1 (acteoside), 5, 6, 8 and 9 on the 1-methyl-4-phenylpyridinium ion (MPP + )-induced cell death in mesencenphalic neurons were investigated. Mesencenphalic neurons treated with MPP + underwent cell death as determined by MTT assay. Simultaneous treatment with the phenylethanoid glycosides markedly attenuated MPP + - induced cytotoxicity.

New dimethylphosphinoyl-substituted α-aminoarylmethanephosphonates 1a - f have been synthesized via addition of dimethyl or diethyl phosphites to Schiff bases and via Kabachnik-Fields reaction. The structure of the compounds was confirmed by elemental analysis, IR, 1 H and 31 P{ 1 H} NMR spectroscopy, mass spectrometry and in two cases by X-ray diffraction.

It is reported on the microwave-assisted synthesis of imidazo- and pyrimidopyrido [4’,3’:4,5]thieno[ 2,3-d]pyrimidines from 2-ethoxymethylene-amino-3-cyano-4,5,6,7-tetrahydrothieno[2,3-c]- pyridine-6-carboxylic acid ethyl ester and 4-chloro-pyridothieno[2,3-d]pyrimidine.

Tris(dimethylamino)ethoxy-methane (3) reacts with 1-alkynes 7a - h to give orthoamides of alkyne carboxylic acids 4a - h.

The diformylation of the dinitriles 4 and diesters 7 with the Bredereck-Simchen reagent HC[N(CH 3 ) 2 ] 2 [OC(CH 3 ) 3 ] (1) under microwave irradiation give the bis-enamines 6 and 8 with dramatically reduced reaction times and improved yields compared to conventional heating. The condensation products formed can be easily converted to bis-pyrazole and bis-isoxazole derivatives 13 and 20, respectively. Methyl anthranilate reacts on prolonged heating with the orthoamide 21 to give ketene aminal 23 in low yield (8 %). Under microwave irradiation the same reagents lead to a mixture of 23 (14 %) and dihydropyrane 24 (28 %).