Gerlinde Frenzen

Configurational stability of chiral organolithium compounds on the time scale of their addition to aldehydes

Abstract A test based on kinetic resolution has been applied to the α-bromo-, α-phenylseleno- and α-phenylthio-alkyl-lithium compounds 1 , which shows that addition of these species to the chiral aldehyde 6 occurs faster than enantiomer equilibration of the organolithium compounds.

Formation of cycloadducts with trans-configurated ester groups from nitrones and dimethyl maleate

Abstract In the 1.3-dipolar cycloaddition of the cyclic nitrone 1c and the acyclic nitrones 8a-h 12a b with dimethyl maleate in refluxing chloroform not only the expected cycloadducts with cis-configuration of the two ester groups were formed but also such with trans-configuration. This phenomenon is not limited to chloroform, but was also observed in polar solvents as cyclohexane and n-hexane. However there is no clue for either a non-concerted reaction course or a subsequent conversion of the cis-products to trans-product in general. Rather conversion of dimethyl maleate to dimethyl fumarate seems to be responsible for the formation of the trans-substituted cycloadducts. This conversion can be induced by small quantities of N-alkylhydroxylamine formed from slight decomposition of nitrones under the reaction conditions or by small quantities of nitrone derivatives possessing a NOH moiety such as N-hydroxy enamine tautomers or nitrone dimers.

(–)‐(M,7S)‐Colchicine and (–)‐(M,7S)‐10‐Ethylthiocolchicide/Alkyne Cycloaddition Reactions: Synthesis of Novel Colchicine Derivatives by Consecutive [4+2] and [3+2] Cycloadditions

Cycloaddition reactions of the facially dissymmetric diene moiety of (–)-(M,7S)-colchicine (5) and (–)-(M,7S)-10-ethylthiocolchicide (9) to various alkynes have been studied. With 5 and the dienophilic benzyne (3), dimethyl acetylenedicarboxylate (DMAD) (4) and cyclooctyne (6) as starting materials all cycloadditions could be realized with high regioselectivity at the 8,12-positions of the alkaloid. The approach of the dienophiles preferentially occurred toward the syn π-face of the diene. In contrast to the cycloaddition mode of 5 the ethylthiocolchicide 9 surprisingly reacted in a different manner. With benzyne as starting material a novel [3+2] cycloaddition of the thioenol ether moiety of 9 towards the dipolarophilic benzyne is supposed, affording the unexpected colchicide 10 after [1,5]H shift of the primarily formed cycloadduct followed by cleavage of the C–S linkage. With DMAD (4) and cyclooctyne (6) the reaction course is more complex. In a consecutive [4+2]/[3+2] cycloaddition (or vice versa) followed by a thermally induced cycloreversion of a not identified intermediate DMAD (4) gives rise to the polycyclic thiophene derivative 13 and the novel allocolchicinoid 14. In a similar way cyclooctyne (6) yielded three products, the thiophene-annulated homobarrelenones 18 and 19 and the tetracyclic allocolchicinoid 21. The structures of the novel colchicine derivatives were assigned on the basis of spectral data, those of the cycloadducts 1 and 19 were verified by X-ray crystallography. For the unprecedented formation of the various allocolchicinoids by consecutive [4+2]/[3+2] cycloadditions plausible reaction pathways are suggested, as far as possible. In addition the inhibitory effects on the tubulin polymerization reaction in vitro of 10, 14, and 21 are reported.

Zur Struktur der Produkte der Reaktion vonE/Z-1-Benzolsulfonyl-3-(1-pentenyl)-indol mit N-Phenylmaleinimid: Ein erster Beitrag zur Konfigurations- und Konformationsanalyse in der Vinylindol-Cycloadditionsreihe

The products2,3 of the reaction ofE/Z-1-benzenesulfonyl-3-(1-pentenyl)-indole (1) and N-phenylmaleimide were analysed by1H-NMR spectroscopy. Exemplarily, the structure elucidation of theendo-cyclo-adduct2 b was achieved by using several NMR techniques (diff. NOE-, INDOR-measurements, decoupling experiments, spectra simulation). The1H-NMR-spectroscopically gained prediction of relative configuration and conformation of2 b was supported on X-ray analysis. The cyclohexene ring of the new cycloadducts adopts in the liquid phase and in the crystal a slightly twisted boat conformation.

Synthese und Kristallstrukturen der Palladium(II)-Komplexe cis- und trans-PdCl2[P(OSiMe3)3]2, {PdCl[PO(OSiMe3)2][P(OSiMe3)3]2} und (NMe2H2)2{Pd2Cl4[P4O5(OSiMe3)4]} / Synthesis und Crystal Structures of the Palladium(II) Complexes cis- and trans-PdCl2[P(OSiMe3)3]2, {PdCl[PO(OSiMe3)2][P(OSiMe3)3]2} and (NMe2H2)2{Pd2Cl4[P4O5(OSiMe3)4]}

The molecular complex PdCl2[P(OSiMe3)3]2 was obtained both as cis- (la) and trans- (lb) isomer from palladium(II) chloride with the equivalent amount of tris(trimethylsilyl)phosphite in a THF suspension at room temperature. With excess P(OSiMe3)3 the complex {PdCI[PO(OSiMe3)2][P(OSiMe3)3]2} (2) is formed with elimination of trimethylchlorosilane. By partial hydrolysis the anionic binuclear palladium complex (NMe2H2)2{Pd2Cl4[P4O5(OSiMe3)4]} (3) is generated from palladium(II) chloride and excess P(OSiMe3)3 in THF in the presence of dimethylamine. All complexes form colourless, moisture-sensitive crystals, which were characterized by X-ray structure determinations. 1a: Space group C2/c, Z = 4,2973 observed unique reflections, R = 0.044. Lattice dimensions at —80°C: a =1052.9(2), b =1675.3(5), c = 2240.1(7) pm, β = 99.88(2)°. The compound has a molecular structure with cis-arrangement of the P(OSiMe3)3 groups with Pd—P bond lengths of 222.9 pm. 1b: Space group P1̄, Z = 1, 3796 observed unique reflections, R = 0.053. Lattice dimensions at-70°C: a = 959.5(2), b = 998.3(2), c =1162.6(2) pm, α=86.99(3)°, β = 81.63(3)°, γ = 62.91(3)°. The compound has a molecular structure with trans-arrangement of the P(OSiMe3)3 groups with Pd—P bond lengths of 230.4 pm. 2: Space group P212121, Z = 4,4444 observed unique reflections, R = 0.055. Lattice dimensions at —70°C: a =1050.0(2), b = 2090.5(3), c = 2357.8(6) pm. The complex has a molecular structure with trans-arrangement of the P(OSiMe3)3 groups with Pd — P bond lengths of 233.6 and 232.1 pm. The Pd—P bond length of the [PO(OSiMe3)2]- ligand is 224.8 pm. 3: Space group P1̄, Z = 2,4762 observed unique reflections, R = 0.071. Lattice dimensions at —80°C: a = 1169.3(6), b = 1299.6(6), c = 1641.7(12) pm, α = 69.19(4)°, β = 87.37(5)°, γ = 80.01(4)°. In the dimeric anion {Pd2Cl4[P4O5(OSiMe3)4]}2- the two cis-PdCl2 units are bridged by the four phosphorus atoms of the [P4O5(OSiMe33)4]2- ligand with average Pd— P bond lengths of 221.5 pm.

Komplexe des Typs [MCl4(SEt2)2] mit M = Mo und W. Kristallstrukturen, NMR-Spektren und magnetisches Verhalten/[MCl4(SEt2)2] Complexes with M = Mo and W. Crystal Structures, NMR Spectra, and Magnetic Behaviour

The crystal structures of the thioether complexes [MCl4(SEt2)2] with M = Mo and W have been solved by X-ray methods. Both compounds crystallize isotypically in the triclinic space group P1̄ with two formula units per cell unit. The metal atoms are octahedrally coordinated by four chlorine atoms and by the two sulfur atoms of the thioether molecules in transposition (symmetry Ci) with bond lengths (average): Mo-Cl 233.1, Mo-S 253.4, W-Cl 233.1, and W-S 251.7 pm. Both complexes were also characterized by 1H and 13C NMR spectroscopy as well as by measurement of the magnetic susceptibilities in the temperature range from 1.8 to 350 K.

Synthese und Kristallstruktur von [VCl2(15-Krone-5)]+[VOCl4]- / Synthesis and Crystal Structure of [VCl2(15-Crown-5)]+[VOCl4]-

[VCl2(15-crown-5)]+[VOCl4]- has been prepared by the reaction of VCl4 with 15-crown-5 in acetonitrile solution in the presence of water, forming black-brown single crystals. They were characterized by IR spectroscopy as well as by an X-ray structure determination. Space group Pnma, Z = 4, 1530 observed unique reflexions, R = 0.052. Lattice dimensions at -120°C: a = 1128.5(4), b = 1063.3(3), c = 1680(1) pm. The compound forms ions, in which the cation contains vanadium(+III), which is seven coordinate by the five oxygen atoms of the crown ether molecule and by two chlorine atoms in axial positions of a pentagonal bipyramide. The [VOCl4]- anion contains vanadium (+V) with approximately tetragonal symmetry

Notizen: Die Kristallstruktur des Rhenium-Tolankomplexes [ReCl4(PhC ≡ CPhXOPCl3)] / The Crystal Structure of the Rhenium-tolane Complex [ReCl4(PhC ≡ CPh)(OPCl3)]

The crystal structure of [ReCl4(PhC = CPh)(OPCl3)] was solved with X-ray methods. Space group P1̄, Z = 2, 2085 observed unique reflections, R = 0.029. Lattice dimensions at -70°C: a = 857.0(2), b = 937.9(2), c = 1249.6(2) pm, α = 87.43(3)°, β = 83.48(3)°, γ = 89.80(3)°. [ReCl4(PhC ≡ CPh)(OPCl3)] has a molecular structure with the alkyne ligand bonded side-on (bond lengths Re-C 198.9(8) and 198.6(7) pm). The oxygen atom of the solvating POCl3 molecule is coordinated in trans position to the ReC2 unit of the alkyne ligand (bond length Re-O 226.7(5) pm).

Die Kristallstrukturen der Palladium(II)-Komplexe [Pd(CH3CN)4](BF4)2, [PdCl(μ2 -PPh2)(HPPh2)]2 · CH2Cl2 und [PdCl(HPPh2) {H(OPPh2)2}] / The Crystal Structures of the Palladium(II) Complexes [Pd(CH3CN)4](BF4)2, [PdCl(μ2-PPh2)(HPPh2)] · CH2Cl2, and [PdCl(HPPh2){H(OPPh2)2}]

The crystal structures of the title compounds were solved by X-ray methods. [Pd(CH3CN)4](BF4)2: Space group Pbca, Z = 4,812 observed unique reflections, R = 0.057, wR = 0.033. Lattice dimensions at -80 °C: α = 1027.5(5), b = 1242.8(6), c = 1280.3(6) pm. The compound consists of planar [Pd(CH3CN)4]2+ ions with Pd-N bond lengths of 195.6 pm and BF4- anions. [PdCl(μ2-PPh2(HPPh2)]2 • CH2Cl2 crystallizes in two polymorphic forms in the same space group type but with different cell parameters, which depends on the conditions of the synthesis. α-form: Space group P21/c, Z = 4, 4680 observed unique reflections, R = 0.041, wR = 0.033. Lattice dimensions at -80 °C: a = 937.2(2), b = 1750.3(6), c = 1593.9(5) pm, β = 106.32(2)°. β-form: Space group Ρ21/n, Ζ = 4, 2519 observed unique reflections, R = 0.105, wR = 0.067. Lattice dimensions at -80 °C: a = 1118.0(4), b = 1222.4(3), c = 1849.9(4) pm, β = 90.72(2)°. Both polymorphs contain centrosymmetric molecules [PdCl μ2- PPh2)(HPPh2)]2 with Pd-P bond lengths of 226.6 pm for the bridging PPh2 groups and Pd-P bond lengths of 232.2 pm for the terminal HPPh2 ligands. [PdCl(HPPh2){H(OPPh2)2}]: Space group Pbca, Z = 8,3673 observed unique reflections, R = 0.038, wR = 0.032. Lattice dimensions at -80 °C: a = 1736.6(3), b = 1874.4(4), c = 1983.1(4) pm. The palladium atom has planar coordination consisting of the chlorine atom, the phosphorus atom of the HPPh2 ligand (Pd-P bond length 235.5 pm), and by the two phosphorus atoms of the H(OPPh2)2 chelate (Pd-P bond lengths 225.9 and 231.0 pm).

Synthese und Kristallstrukturen der ionischen Kronenetherkomplexe [TiCl3(15-Krone-5)(CH3CN)][SbCl6) und [VCI(OH)(18-Krone-6)(CH3CN)2][SbCl6] · ½(18-Krone-6 · CH3CN) / Synthesis and Crystal Structures of the Ionic Crown Ether Complexes [TiCl3(15-Crown-5)(CH3CN)][SbCl6) und [VCI(OH)(18-Crown-6)(CH3CN)2][SbCl6] · ½(18-Crown-6 · CH3CN)

Abstract The title compounds were prepared by the reaction of titanium tetrachloride with 15-crown-5 and antimony pentachloride, and by the reaction of vanadium trichloride with 18-crown-6 and antimony pentachloride in the presence of traces of water in acetonitrile solution, respectively. The complexes were characterized by IR spectroscopy and by X-ray structure determinations. [TiCl3(15-crown-5)(CH3CN)][SbCl6]: Space group Pnma, Z = 4, 1355 observed unique reflections, R = 0.035. Lattice dimensions at -80 °C: a = 1987(1), b = 1742.2(6), c = 111.0(2) pm. The compound consists of SbCl6- anions and cations [TiCl3(15-crown-5)(CH3CN)]+, in which the titanium atom is coordinated octahedrally by three chlorine atoms in facial arrangement, by the nitrogen atom of the acetonitrile molecule, and by two oxygen atoms of the crown ether molecule. [VCl(OH)(18-crown-6 )(CH3CN)2][SbCl6] · ½(18-crown-6 · CH3CN); Space group P 1̄, 3936 observed unique reflections, R = 0.714. Lattice dimensions at -80 °C: a = 1194.2(6), b = 1349.8(6), c = 1365.5(6) pm, α = 93.55(4)°, β = 111.23(4)°, γ = 93.15(4)°. The compound consists of SbCl6- anions, included 18-crown-6 and acetonitrile molecules, and cations [VCl(OH)(18-crown-6)(CH3CN)2]+, in which the vanadium atom is octahedrally coordinated by two nitrogen atoms of the acetonitrile molecules in trans positions, by a chlorine atom and a hydroxyl group in cis position, and by two oxygen atoms of the crown ether molecule. One of the acetonitrile molecules forms weak hydrogen bridges with two oxygen atoms of the included crown ether molecule as well as with one chlorine atom of the SbCl6- ion.