Search results for "Moiety"

Atom Transfer Radical Addition Catalyzed by Ruthenium–Arene Complexes Bearing a Hybrid Phosphine–Diene Ligand

2018

International audience; The synthesis and characterization of a series of arene ruthenium complexes bearing either (3,5-cycloheptadienyl)diphenylphosphine or (cycloheptyl)-diphenylphosphine are reported. Upon irradiation or heating, all these complexes lose their arene ligand but then exhibit a different behavior depending on the nature of the phosphine ligand. (Cycloheptadienyl)phosphine complexes 1 and 3 give a cationic dinuclear Ru complex 5 for which the two Ru atoms are bridged by three chlorido ligands and flanked by two tridendate (cycloheptadienyl)phosphines. (Cycloheptyl)-diphenylphosphine complexes 2 and 4 undergo arene exchange when toluene is used as solvent or degrade in dithlo…

Substituent Effect in 2-Benzoylmethylenequinoline Difluoroborates Exhibiting Through-Space Couplings. Multinuclear Magnetic Resonance, X-ray Diffract…

2012

The series of nine 2-benzoylmethylenequinoline difluoroborates have been synthesized and characterized by multinuclear magnetic resonance, X-ray diffraction (XRD), and computational methods. The through-space spin-spin couplings between (19)F and (1)H/(13)C nuclei have been observed in solution. The NMR chemical shifts have been correlated to the Hammett substituent constants. The crystal structures of six compounds have been solved by XRD. For two derivatives the X-ray wave function refinement was performed to evaluate the character of bonds in the NBF(2)O moiety by topological and integrated bond descriptors.

Efficient synthesis and structural analysis of new dioxopiperazine isoquinolines

2006

Abstract We report herein the synthesis of new dioxopiperazine isoquinolines using the Pictet–Spengler cyclisation. Our synthetic strategy for the preparation of two new compounds ( 5 , 6 ), with a tetrahydro-6H-pyrazino[1,2-b]isoquinoline-1,4-dione moiety was developed in only four steps. To understand better the crucial step of the synthesis reported here, theoretical calculations using semiempirical (PM3), ab initio and DFT computations were carried out on a reduced system model. The structure of chlorohydrate water solvate of tetrahydro (2-piperidinylethyl)-6H-pyrazino [1,2-b]isoquinoline-1,4-dione ( 6·HCl·2H2O ) was determined by X-ray diffraction. Theoretical calculations (RHF/3-21G a…

Crystal structure of 4,6-O-ethylidene-N-(2-hydroxybenzylidene)-β-D-glucopyranosylamine

2002

4,6-O-Ethylidene-N-(2-hydroxybenzylidene)-β-D-glucopyranosylamine was synthesized and characterized using analytical, spectral and single-crystal X-ray diffraction methods. The anomeric nature of the saccharide moiety was proposed based on 1H NMR studies and was confirmed by the crystal structure. The lattice structure of this compound was compared with that of its analogues.

Coupling of Benzynezirconocene with 1,4-Diphenyl-1,3-butadiyne

2000

The thermolysis of diphenylzirconocene in the presence of 1,4-diphenyl-1,3-butadiyne to yield the seven-membered zirconacyclocumulene 1 via the intermediacy of benzynezirconocene is described. This complex has been characterized by an X-ray diffraction study. Additionally, better knowledge of the bonding of the cumulene moiety was achieved by DFT calculations. Cleavage of the Zr−C bonds of 1 with methanol provided the corresponding butatriene 2.

Liquid structure of dibutyl sulfoxide

2016

We present experimental (X-ray diffraction) data on the structure of liquid dibutyl sulfoxide at 320 K and rationalise the data by means of molecular dynamics simulations. Not unexpectedly, DBSO bearing a strong dipolar moiety and two medium length, apolar butyl chains, this compound was characterised by a distinct degree of polar vs. apolar structural differentiation at the nm spatial scale, which was fingerprinted by a low Q peak in its X-ray diffraction pattern. Similar to, but to a larger extent than its shorter chain family members (such as DMSO), DBSO was also characterised by an enhanced dipole-dipole correlation, which was responsible for a moderate Kirkwood correlation factor as we…

Synthesis and comparison of the antiinflammatory activity of manoalide and cacospongionolide B analogues.

1998

We have synthesized analogues of two naturally occurring antiinflammatory marine compounds, manoalide and cacospongionolide B, containing a pyranofuranone moiety which is considered the pharmacophoric group. The two compounds, and hence their analogues, differ in the presence or absence in the dihydropyran ring of an hemiacetal function which was considered essential to irreversibly inactivate phospholipase A 2 (PLA 2 ). The two series of compounds were tested for their inhibitory effects on secretory PLA 2 belonging to the groups I, II, and III, and the activities were found to be similar in both series, irrespective of the presence or absence of the additional hemiacetal function. In addi…

ChemInform Abstract: Regiospecific and Stereoselective Ene Reaction of the A-Ring Methylcyclohexene Moiety of Polycyclic Terpenoid Systems with Dimet…

2010

Regiospecific and stereoselective ene reaction of the A-ring methylcyclohexene moiety of polycyclic terpenoid systems with dimethyl acetylenedicarbox…

2001

Polycyclic terpenoid compounds with a methylcyclohexene moiety at the A-ring, such as 1 and 7, give a regio- and stereoselective ene reaction when heated at low temperatures with dimethyl acetylenedicarboxylate. The structure and stereochemistry of the compound formed in the case of 1, e.g. 5, is determined by X-ray analysis.

Two atropisomers of tricarbonyl[η6-7-chloro-3-(3-chloro-2-methylphenyl)-2,4,8-trimethyl-1,2,3,4-tetrahydro-2,4-dibora-1,3-diazanaphthalene]chromium(0)

2001

The structures of two atropisomers of the title compound, [Cr(C16H18B2Cl2N2)(CO)3], are reported. For both compounds, the Cr(CO)3 moiety is bound to the C6 aromatic ring of the mol­ecule; the existence of atropisomers resulting from the non-equivalence of both faces of the C6 aromatic ring is a consequence of the 3-chloro-2-methylphenyl ring being nearly perpendicular to the mean plane of the 2,4-dibora-1,3-di­aza­naphthalene ring. The orientation of the Cr(CO)3 tripod relative to the C6 aromatic ring is such that it is nearly eclipsed in one isomer (2.4° rotation from being eclipsed with C—N, C—Cl and C—H) and slightly twisted (16.2°) from an eclipsed conformation in the other.