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61.
Alok K. Mukherjee Subhadra Guha M. Wahab Khan Nitya G. Kundu Madeleine Helliwell 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(1):85-87
Two isoindolin‐1‐one derivatives, (Z)‐3‐benzylidene‐N‐phenylisoindolin‐1‐one, C21H15NO, (II), and (Z)‐3‐benzylidene‐N‐(4‐methoxyphenyl)isoindolin‐1‐one, C22H17NO2, (III), were synthesized by the palladium‐catalysed heteroannulation. The molecules of both compounds have a Z configuration. The interplanar angles between the five‐ and six‐membered rings of the isoindolinone moiety in (II) and (III) are 1.66 (11) and 2.26 (7)°, respectively. The phenyl rings at the N‐position in (II) and (III) are twisted out of the C4N ring plane by 62.77 (11) and 67.10 (7)°, respectively. The substitutions at the N and C‐3 positions of the isoindolinone system have little influence on the molecular dimensions of the resulting compounds. 相似文献
62.
Atom transfer cyclization reactions (ATRC) provide rapid access to functionalized γ-butyrolactones. 相似文献
63.
64.
Treatment of the thf adduct UO2(NCN)thf (NCN = [(Me3SiN)CPh(NSiMe3)]) (1) with 2 equiv of B(C6F5)3 provides UO{OB(C6F5)3}(NCN)2 (2) the first example of a neutral uranyl complex exhibiting Lewis basic behavior. The crystal structure of 2 shows a U=O-B interaction with an elongated U=O bond (1.898(3) A). Raman spectroscopy suggests weakening of the O=U=O bonding, giving the lowest reported symmetric stretching frequency for a monomeric uranyl complex, nu1 = 780 cm-1. The borane can be selectively removed using PMe3 to give the coordinatively unsaturated UO2(NCN)2 (3) or using tBuNC to provide UO2(CNBut)(NCN)2 (4), the first example of an isonitrile coordinated to uranium. 相似文献
65.
Donohoe TJ Raoof A Freestone GC Linney ID Cowley A Helliwell M 《Organic letters》2002,4(18):3059-3062
[reaction: see text] The stereoselective Birch reduction of 3-methyl-2-furoic acids using a readily available chiral auxilairy is described; by coupling this process to an oxidative cleavage/aldol ring closure sequence we were able to produce highly functionalized and enantiopure dihydropyranones in high yield. This sequence has ample flexibility built into it, either by the use of different electrophiles during reductive alkylation or by subsequent derivatization of the dihydropyranone after ring expansion. 相似文献
66.
Madeline S. Toy Roger S. Stringham 《Journal of polymer science. Part A, Polymer chemistry》1978,16(11):2781-2795
High-resolution nuclear magnetic resonance (NMR) spectroscopy was used to determine the microstructures of some perfluorocarbocyclic ethers and polymers from reactions of bis(fluoroxy)-difluoromethane and hexafluorobenzene. The thermal and photochemical reactions of CF2(OF)2 and excess hexafluorobenzene are described. The structures of several new perfluoro-1,3-dioxolanes in which the rings constituted part of a bicyclic system were elucidated by 19F-NMR, gas chromatograph, gas chromatograph-infrared, and gas chromatograph-mass spectra. The copolymers of molecular weight about 2500 are, with 40% of the difluoromethylenedioxy groups, estimated by 19F-NMR to be in the polymer chain and the rest as pendant groups to the perfluorocyclohexylene and perfluorocyclohexenylene moieties. The suggested polymer structures are described and the mechanisms discussed. 相似文献
67.
Madeline S. Toy J. Melford Newman 《Journal of polymer science. Part A, Polymer chemistry》1969,7(8):2333-2340
Perfluorobutadiene was polymerized in bulk under low pressure and temperature in the presence of diisopropyl peroxydicarbonate, bis(trifluoromethyl) peroxide, and benzoyl peroxide. Fractional solvent extraction of polyperfluorobutadiene by n-hexane and hexafluorobenzene into three polymeric fractions was described. The hexafluorobenzene-soluble fraction was used for crosslinking studies. Direct fluorination of solid polyperfluorobutadiene required no catalyst. The fluorine–polyperfluoropolyene reactions furnished a mechanism for crosslinking the unsaturated chains. Fluorination by gaseous fluorine formed free radical sites on the polymer chains besides saturation reactions. The presence of excess monomer in contact with these partially fluorinated solid polyperfluorobutadienes under controlled conditions were capable of crosslinking and grafting to the linear chains. Direct fluorination of solid polyperfluorobutadiene tends to involve reaction with the internal double bonds rather than the pendant perfluorovinyl group; the converse is true for crosslinking with hexamethylenediamine. The mechanisms are discussed. 相似文献
68.
Chi-Ta Lee Dr. Helan Wang Ming Zhao Dr. Tung-Han Yang Dr. Madeline Vara Prof. Dr. Younan Xia 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(20):5322-5329
The rational design and implementation of a one-pot method is reported for the facile synthesis of Pd@PtnL (nL denotes the number of Pt atomic layers) core-shell icosahedral nanocrystals in a single step. The success of this method relies on the use of Na2PdCl4 and Pt(acac)2 as the precursors to Pd and Pt atoms, respectively. Our quantitative analysis of the reduction kinetics indicates that the PdII and PtII precursors are sequentially reduced with a major gap between the two events. Specifically, the PdII precursor is reduced first, leading to the formation of Pd-based icosahedral seeds with a multiply-twinned structure. In contrast, the PtII precursor prefers to take a surface reduction pathway on the just-formed icosahedral seeds. As such, the otherwise extremely slow reduction of the PtII precursor can be dramatically accelerated through an autocatalytic process for the deposition of Pt atoms as a conformal shell on each Pd icosahedral core. Compared to the conventional approach of seed-mediated growth, the throughput for the one-pot synthesis of Pd@PtnL core-shell nanocrystals can be increased by more than 30-fold. When used as catalysts, the Pd@Pt4.5L core-shell icosahedral nanocrystals show specific and mass activities of 0.83 mA cm−2 and 0.39 A mgPt−1, respectively, at 0.9 V toward oxygen reduction. The Pt-based nanocages derived from the core-shell nanocrystals also show enhanced specific (1.45 mA cm−2) and mass activities (0.75 A mgPt−1) at 0.9 V, which are 3.8 and 3.3 times greater than those of the commercial Pt/C, respectively. 相似文献
69.
Philip A. Helliwell Ruth E. Fake Kevin G. Kerr Barbara Santry Austen Speakman 《合成通讯》2013,43(20):3058-3066
A novel microwave-assisted synthesis of a library of triarylamides has been undertaken on the solid-phase. 相似文献
70.
Rupam Sen Dipak K. Hazra Subratanath Koner Madeleine Helliwell Monika Mukherjee Ashis Bhattacharjee 《Polyhedron》2010
A series of dimeric lanthanide carboxylato complexes [La(5-Br-NIC)3(H2O)2]2·H2O (1); [Gd(5-Br-NIC)3(H2O)2]2 (2), [5-Br-NIC = 5-bromonicotinate] and [Sm(NIC)3(H2O)2]2 (3) [NIC = nicotinate], have been hydrothermally synthesized and structurally characterized by single crystal X-ray analysis. Complexes 1, 2 and 3 are of similar structure and consist of a basic unit [La(carboxylato)3(H2O)2]2. In compound 1 lanthanide cation is surrounded by one chelating 5-bromo-nicotinato ligand, two bridging oxygen atoms from 5-bromo-nicotinato and two water molecules, in which each La(III) ion is nine coordinated in a tricapped prismatic geometry. However, in compounds 2 and 3 four carboxylate groups link a pair of lanthanide atoms in the O,O′-bridging mode to generate a paddle-wheel-like centrosymmetric dimer. All the compounds exhibit excellent catalytic performance in olefin epoxidation reaction. The variable temperature magnetic susceptibility measurements showed that the magnetic interaction in [Gd(5-Br-NIC)3(H2O)2]2 (2), is antiferromagnetic (J = −0.048 cm−1), while compound [Sm(NIC)3(H2O)2]2 (3), showed a complicated low-temperature magnetic property. 相似文献