Search results for "Yield"
showing 10 items of 1338 documents
Synthesis of pyrrolo[3′,4′:2,3]azepino[4,5,6-cd]indole-8,10-diones
2000
3-Amino-4-(3-indolyl)pyrrolin-2,5-diones are condensed with various aldehydes and ketones to the cor responding imines. Under Pictet-Spengler conditions, the latter do not cyclize to pyrrolo-β-carbolines, but readily yield pyrrolo[3′,4′:2,3]azepino[4,5,6-cd]indole-8,10-diones.
The fischer indole synthesis of 8-methyl-5-substituted-1-oxo-β-carbolines: A remarkable high yield of a [1,2]-methyl migration.
1991
Abstract A very unusual high yield of rearranged products (via methyl migration) has been obtained in the Fischer indole cyclization of the 3-(2,5-dimethyl phenylhydrazone) of 2,3-piperidine dione (6b). When a less activated aromatic ring is present in the phenylhydrazone 6, such a behaviour is not observed and cyclization occurs essentially without rearrangement.
Essential on the Photophysics and Photochemistry of the Indole Chromophore by Using a Totally Unconstrained Theoretical Approach
2015
Indole is a chromophore present in many different molecules of biological interest, such as the essential amino acid tryptophan and the neurotransmitter serotonin. On the basis of CASPT2//CASSCF quantum chemical calculations, the photophysical properties of the system after UV irradiation have been studied through the exploration of the potential energy hypersurfaces of the singlet and triplet low-lying valence excited states. In contrast to previous studies, the present work has been carried out without imposing any restriction to the geometry of the molecule (C1 symmetry) and by performing minimum energy path calculations, which is the only instrument able to provide the lowest-energy evo…
Total Synthesis of Phenanthroindolizidine Alkaloids by Combining Iodoaminocyclization with Free Radical Cyclization
2016
A concise and modular synthesis of phenanthroindolizidine alkaloids was achieved by combining iodoaminocylization with a free radical cyclization approach. The route described allowed the preparation of (±)-tylophorine, (±)-antofine, and (±)-deoxypergularinine in six steps. When commercially available l-prolinol was used as a chiral building block, (S)-(+)-tylophorine was also synthesized in 49% yield and >99% ee over five linear steps.
Interest rate co-movements, global factors and the long end of the term spread
2012
The disconnect between rising short and low long interest rates has been a distinctive feature of the 2000s. Both research and policy circles have argued that international forces, such as global monetary policy (e.g. Rogoff, 2006); international business cycles (e.g. Borio and Filardo, 2007); or a global savings glut (e.g Bernanke, 2005) may be responsible. In this paper, we employ recent advances in panel data econometrics to document the disconnect and link it explicitly to the existence of a global latent factor that dominates the long end of the term spread for the recent period; the saving glut story emerges as the most likely contender for the global factor.
Transient Midinfrared Study of Light Induced Dissociation Reaction of Ru(dcbpy)(CO)2I2 in Solution
2004
Illumination of Ru(dcbpy)I2(CO)2 (dcbpy = 4,4‘-dicarboxy-2,2‘-bipyridine) with (near) ultraviolet light induces dissociation of one of the CO groups of the complex. In solution the opened coordination site of the metal is occupied by a solvent molecule. In the present study the kinetics of the ligand exchange reaction has been studied in solution with femtosecond time resolution by probing the CO stretching vibrations of the reactant and the product molecules Ru(dcbpy)I2(CO)(EtOH) in the infrared and probing electronic transitions in the visible spectral regions. The kinetic results indicate that photoelimination of the CO group occurs on a subpicosecond time scale. The overall quantum yiel…
Heptanuclear high-spin complex compounds based on S-donors
2007
Abstract The precursors [Fe(III)( SY L)Cl] ( SY LH 2 ) = N , N ′-bis(1-hydroxy-Y-2-benzyliden)-1,6-diamino-3-thiohexane, (Y = H, 3EtO, 5Me) are high-spin ( S = 5/2) complexes. The precursors are combined with [Fe(II)(CN) 6 ] 4− and [Co(III)(CN) 6 ] 3− to yield star-shaped heptanuclear clusters, [Fe(II)(CN–Fe(III) SY L) 6 ]Cl 2 and [Co(III)(CN–Fe(III) SY L) 6 ]Cl 3 . The star-shaped compounds are high-spin (HS) systems at room temperature. On cooling to 20 K some of the iron(III) centers perform some HS–HS transition.
Reactivity of Distibanes toward Trialkylalanes and -gallanes: Syntheses and X-ray Structures of Bisadducts and Heterocycles
2001
Reactions between distibanes of the type Sb2R4 and trialkylalanes and -gallanes R‘3M in 1:2 stoichiometry yield eight bisadducts of the type [Sb2R4][MR‘3]2 (R = Me, R‘ = t-Bu, M = Al 1, Ga 2; R = Et, M = Al, R‘ = Me 3, Et 4, t-Bu 5; M = Ga, R‘ = Me 6, Et 7, t-Bu 8), which were characterized by multinuclear NMR studies and elemental analysis. In addition, 1, 2, 5, and 8 are the first structurally characterized neutral main group Lewis acid−distibane bisadducts. 1−8 are unstable in solution toward the formation of heterocycles of the type [R2SbMR‘2]x. [Me2SbGa(t-Bu)2]3 (9) and [Et2SbGa(t-Bu)2]2 (10) have been isolated and their solid state structures determined by single-crystal X-ray diffrac…
A Trinuclear Aqua Cyano‐Bridged Ruthenium Complex [{(η 5 ‐C 5 H 5 )(PPh 3 ) 2 Ru(μ‐CN)} 2 RuCl 2 (PPh 3 )(H 2 O)]PF 6 : Synthesis, Characterization a…
2007
The organometallic trinuclear aqua cyano-bridged complex [{(η5-C5H5)(PPh3)2Ru(μ-CN)}2RuCl2(PPh3)(H2O)]PF6 (1), in which the fragment [RuCl2(PPh3)(H2O)] acts as a bridge and an acceptor group between the two terminal cyclopentadienyl ruthenium cyano moieties, was isolated in moderate yield from the reaction of [(η5-C5H5)(PPh3)2RuCN] with [RuCl2(PPh3)3] in THF. To the best of our knowledge, compound 1 is one of the few examples of a trinuclear array of ruthenium fragments bridged by the nitrogen atom of the–C≡N– group (Ru–C≡N–Ru′–N≡C–Ru) with a Ru-coordinated water molecule. The new aqua complex was structurally characterized by FTIR, 1H, 13C, and 31P NMR spectroscopy, mass spectrometry, elem…
Effect of free rotation in polypyridinic ligands of Ru(ii) complexes applied in light-emitting electrochemical cells
2013
In the present work we report the synthesis and the electrochemical, photoluminescent and electroluminescent properties of two new Ru(II) complexes described by the general formula [Ru(phen)2X](2+), where phen is 1,10-phenanthroline. The X ligand consists of a 2,2'-bipyridine (bpy) unit substituted with two phenyl rings connected to the bpy core through a saturated (Lhydro = 4,4'-diphenylethyl-2,2'-bipyridine) or a conjugated (LH = 4,4'-bis(α-styrene)-2,2'-bipyridine) carbon-carbon bridge. The photoluminescent spectra indicate that, both in solution and solid state, the complex bearing the aliphatic substitution bridges exhibits a higher quantum yield and a longer excited state lifetime tha…