Voici les éléments 1 - 10 sur 16
  • Publication
    Métadonnées seulement
    Synthesis of α,β'- and β,β'-linked dimethoxycarbonyldipyrromethanes by Rothemund-type condensation
    The Rothemund-type condensation of methoxycarbonylpyrrole with acetone produces mainly the α,β'-linked dipyrromethane, a building block for the synthesis of N-confused macrocycles. The influence of the reaction conditions on the regioselectivity of the process is reported. The x-ray structures of the α,α'-, α,β'- and β,β'-linked dipyrromethanes show an interesting discrimination of the structurally different types of hydrogen bonds. [on SciFinder(R)]
  • Publication
    Métadonnées seulement
    2,2'-[(2S*,6R*)-Piperidine-2,6-diyl]dipropan-2-ol
    In the title compd., C11H23NO2, the piperidine ring has a chair conformation. The two hydroxy H atoms are disordered over two positions with fixed occupancy ratios of 0.57:0.43 and 0.63:0.37. In the mol., there are two short N-H···O interactions. In the crystal, four symmetry-related mols. are linked by O-H···O H bonds to form a cage-like arrangement, centered about the point of intersection of three 2-fold axes. These cages stack along the [100] direction. Crystallog. data and at. coordinates are given. [on SciFinder(R)]
  • Publication
    Métadonnées seulement
    Catalytic Epoxidation of Alkenes by the Manganese Complex of a Reduced Porphyrinogen Macrocycle
    (2012)
    Bruyneel, Frederic
    ;
    Letondor, Christophe
    ;
    Bastuerk, Bjorn
    ;
    Gualandi, Andrea
    ;
    ; ;
    The present paper details the first application of a fully reduced meso-octamethylporphyrinogen macrocycle as an effective ligand for simple operative manganese-catalyzed alkene epoxidn. The efficiency of the novel catalyst was detd. in the presence of various oxidants, apical ligands and acidic/basic additives. Higher reactivity was found in favor of electron-rich alkenes, whereas an electron-deficient conjugated alkene appeared to be a poor substrate in the screening. Sulfur additives were active as apical ligands, whereas nitrogen-contg. additives influenced the reactivity only moderately. Cis-Stilbene and 3?-acetoxy-5-cholestene were epoxidized in a stereoselective manner. The x-ray structures of the new manganese complexes were detd. and showed a rigid planar coordination geometry of the satd. macrocyclic ligand to the metal center. [on SciFinder(R)]
  • Publication
    Métadonnées seulement
    4-Methoxybenzoyl-meso-octamethylcalix[2]pyrrolidino[2]pyrrole: an acyl chloride derivative of a partially reduced calix[4]pyrrole
    In the title compd., C36H50N4O2, the two pyrrolidine rings have envelope conformations. The conformation of the macrocycle is stabilized by N-H···N H bonds and a C-H···N interaction. The benzoyl ring is inclined to an adjacent pyrrole ring by 6.76(9)°, with a centroid-to-centroid distance of 3.6285(10) Å. In the crystal, apart from a C-H···O and a C-H···? interaction, mols. are linked via an N-H···O H bond, giving helical chains propagating along [010]. Crystallog. data and at. coordinates are given. [on SciFinder(R)]
  • Publication
    Métadonnées seulement
    4-Chlorobenzoyl-meso-octamethylcalix[2]pyrrolidino[2]pyrrole: an acyl chloride derivative of a partially reduced calix[4] pyrrole
    In the title compd., C35H47ClN4O, the two pyrrolidine rings have envelope conformations. The conformation of the macrocycle is stabilized by N-H···N H bonds and a C-H···N interaction. The benzoyl ring is inclined to the adjacent pyrrole ring by 11.66(11)°, with a centroid-centroid distance of 3.7488(13) Å. In the crystal, mols. are linked by N-H···O H bonds into helical chains propagating in [010] and C-H···O and C-H···? interactions are also obsd. [on SciFinder(R)]
  • Publication
    Métadonnées seulement
    2-[2-(Pyrrolidin-2-yl)propan-2-yl]-1H-pyrrole and its amide derivative 1-{2-[2-(1H-pyrrol-2-yl)propan-2-yl]pyrrolidin-1-yl}ethanone
    In the title compds., C11H18N2, (II), and C13H20N2O, (III), the pyrrolidine rings have twist conformations. Compd. (II) crystallizes with two independent mols. (A and B) in the asym. unit. The mean planes of the pyrrole and pyrrolidine rings are inclined to one another by 89.99 (11) and 89.35 (10)° in mols. A and B, resp. In (III), the amide deriv. of (II), the same dihedral angle is much smaller, at only 13.42 (10)°. In the crystal structure of (II), the individual mols. are linked via N-H···N hydrogen bonds to form inversion dimers, each with an R22(12) graph-set motif. In the crystal structure of (III), the mols. are linked via N-H···O hydrogen bonds to form inversion dimers with an R22(16) graph-set motif. [on SciFinder(R)]
  • Publication
    Métadonnées seulement
    2-(2-Naphthyl)-1,3-dioxane
    The title compd., C14H14O2, crystallizes in the chiral monoclinic space group P21. Crystallog. data and at. coordinates are given. This acetal is composed of a planar naphthalene ring with a 1,3-dioxane ring substituent, which has a chair conformation. In the crystal structure, symmetry-related mols. are connected via a weak C-H...O interaction to form a helical chain propagating in [010]. While there are no ?-? stacking interactions present, there are weak C-H...? interactions involving the naphthalene arom. rings, which link the helical chains to form a two-dimensional network in the (011) plane. [on SciFinder(R)]
  • Publication
    Métadonnées seulement
    4,4-Bis(1H-pyrrol-2-yl)pentanol
    The achiral 4,4-bis(1H-pyrrol-2-yl)pentanol, C13H18N2O, crystd. in the chiral monoclinic space group P21. The pyrrole rings are inclined to 1 another by 62.30(11)°, and the PrOH chain is in an extended conformation. In the crystal, the 2 pyrrole NH groups are involved in intermol. N-H···O H bonds, giving a helical arrangement propagating along the b axis. An interesting feature of the crystal structure is the absence of any conventional H bonds involving the hydroxy H atom. There is a weak intermol. O-H···? interaction involving 1 of the pyrrole rings. Crystallog. data are given. [on SciFinder(R)]
  • Publication
    Métadonnées seulement
    1,4-Bis(hexyloxy)-2,5-diiodobenzene
    (2010) ; ;
    Sereda, Olha
    ;
    Neels, Antonia
    ;
    The centrosym. title compd., C18H28I2O2, crystd. in the monoclinic space group P21/c with the alkyl chains having extended all-trans conformations, similar to those in the centrosym. bromo analog that crystd. in the triclinic space group P?1. The difference between the 2 structures lies in the orientation of the 2 alkyl chains with respect to the C(arom.)-O bond. In the title compd., the O-Calkyl-Calkyl-Calkyl torsion angle is 55.8(5)°, while in the bromo analog this angle is -179.1(2)°. In the title compd., the C-atoms of the alkyl chain are almost coplanar [max. deviation of 0.052(5) Å] and this mean plane is inclined to the benzene ring by 50.3(3)°. In the bromo-analog, these 2 mean planes are almost coplanar, making a dihedral angle of 4.1(2)°. Another difference between the crystal structures of the 2 compds. is that in the title compd. there are no halide...halide interactions. Instead, symmetry-related mols. are linked via C-H...? contacts, forming a 2D network. Crystal data: monoclinic, P21/n, a = 9.441(9), b = 7.8455(6), c = 13.457(2) Å, ? = 92.148(12)°, Z = 2, 1216 obsd. reflections with I > 2(I), 101 refined parameters, R[F2 > 2?(F2)] = 0.029, wR(F2) = 0.055. [on SciFinder(R)]
  • Publication
    Métadonnées seulement
    2,2'-(Propane-2,2-diyl)bis(1H-pyrrole)
    2,2'-(Propane-2,2-diyl)bis(1H-pyrrole), C11H14N2, crystd. with 2 independent mols. (A and B) in the asym. unit. The 2 mols. differ only slightly, with the pyrrole rings being inclined to 1 another at a dihedral angle of 87.67(8)° in mol. A and 88.09(7)° in mol. B. In the crystal, there are no classical H bonds, but the 2 pyrrole NH groups of 1 mol. are involved in N-H···? interactions with the pyrrole rings of the other mol. In this manner, a compact box-like arrangement of the 2 independent mols. is formed. Crystallog. data are given. [on SciFinder(R)]