The Experts below are selected from a list of 588 Experts worldwide ranked by ideXlab platform
Bekir Cetinkaya - One of the best experts on this subject based on the ideXlab platform.
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synthesis characterization and catalytic application of secondary carbene palladium ii complexes obtained by oxidative addition reaction
Inorganica Chimica Acta, 2012Co-Authors: Suleyman Gulcemal, Salih Gunnaz, Jeanclaude Daran, Bekir CetinkayaAbstract:Abstract Three new secondary carbene palladium(II) complexes (1b–3b) were synthesized via oxidative insertion of Pd2(dba)3 (dba = Dibenzylideneacetone) into the C–Cl bond of dialkyl(chloromethylene)ammonium chloride salts ([R2NCHCl]+Cl−). All complexes have been characterized by 1H, 13C, and 31P NMR analysis. X-ray diffraction studies on single crystal of 3b confirm the cis square planar geometry. Complexes (1b–3b) have been proved to be efficient catalysts in the Heck coupling of styrene with 4-bromoacetophenone.
Seth B Herzon - One of the best experts on this subject based on the ideXlab platform.
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room temperature palladium mediated p arylation of secondary phosphine oxides
Organic Letters, 2012Co-Authors: Aaron J Bloomfield, Seth B HerzonAbstract:We show that a broad range of aryl iodides are efficiently coupled with secondary phosphine oxides using 1 mol % of a catalyst formed in situ from tris(Dibenzylideneacetone)dipalladium and Xantphos (1). Scalemic (S)-methylphenylphosphine oxide [(S)-2e] is shown to undergo arylation without detectable stereoerosion. The application of this method to the synthesis of novel P-chiral phosphines and PCP ligands is demonstrated.
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Room Temperature, Palladium-Mediated P–Arylation of Secondary Phosphine Oxides
2012Co-Authors: Aaron J Bloomfield, Seth B HerzonAbstract:We show that a broad range of aryl iodides are efficiently coupled with secondary phosphine oxides using 1 mol % of a catalyst formed in situ from tris(Dibenzylideneacetone)dipalladium and Xantphos (1). Scalemic (S)-methylphenylphosphine oxide [(S)-2e] is shown to undergo arylation without detectable stereoerosion. The application of this method to the synthesis of novel P-chiral phosphines and PCP ligands is demonstrated
Boli Liu - One of the best experts on this subject based on the ideXlab platform.
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radiolabeled pyridinyl analogues of Dibenzylideneacetone as β amyloid imaging probes
RSC Advances, 2016Co-Authors: Xiaomei Cui, Boli Liu, Xiaoyang Zhang, Cheng Peng, Jiapei Dai, Mengchao CuiAbstract:In continuation of our investigation of the Dibenzylideneacetone scaffold as Aβ imaging probes, a series of derivatives containing pyridine rings with lower lipophilicity was synthesized and evaluated. Some of these probes displayed high affinities to Aβ1–42 aggregates, which ranged from 18.0 to 8.2 nM. The high and specific binding of the radiolabeled tracers was further confirmed by in vitro autoradiography on brain sections from AD patients and transgenic mouse. In biodistribution experiments, two 18F-labeled tracers [18F]17a and [18F]18 displayed high initial brain uptake (5.05 and 6.24% ID g−1, respectively, at 2 min postinjection) and fast clearance from the brain with brain2 min/brain60 min ratios of 6.08 and 8.00. These results demonstrate that the probes [18F]17a and [18F]18 with a Dibenzylideneacetone structure containing pyridine rings have great strength in imaging Aβ plaques in the brain.
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novel 18f labeled Dibenzylideneacetone derivatives as potential positron emission tomography probes for in vivo imaging of β amyloid plaques
European Journal of Medicinal Chemistry, 2014Co-Authors: Mengchao Cui, Jiapei Dai, Hongmei Jia, Jinming Zhang, Xiaojun Zhang, Peng Chen, Boli LiuAbstract:Abstract A series of Dibenzylideneacetones were synthesized and evaluated as imaging probes for β -amyloid plaques. They displayed high binding affinity to A β 1–42 aggregates ( K i = 6.4 for 8 , K i = 3.0 for 9 ), and the high binding were confirmed by in vitro autoradiography with AD human and transgenic mouse brain sections. Two of them were selected for 18 F-labeling directly on the benzene ring. In biodistribution experiments, [ 18 F] 8 and [ 18 F] 9 displayed high initial uptakes (9.29 ± 0.41 and 5.38 ± 0.68% ID/g) and rapid washouts from the normal brain (brain 2 min /brain 60 min ratios of 21.6 and 13.4). These preliminary results suggest that [ 18 F] 8 and [ 18 F] 9 may be used as potential PET imaging agents for the detection of A β plaques in the brain.
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99m tc labeled Dibenzylideneacetone derivatives as potential spect probes for in vivo imaging of β amyloid plaque
European Journal of Medicinal Chemistry, 2013Co-Authors: Yanping Yang, Mengchao Cui, Bing Jin, Xuedan Wang, Jianhua Jia, Hongmei Jia, Boli LiuAbstract:Four (99m)Tc-labeled Dibenzylideneacetone derivatives and corresponding rhenium complexes were successfully synthesized and biologically evaluated as potential imaging probes for Aβ plaques using SPECT. All rhenium complexes (5a-d) showed affinity for Aβ(1-42) aggregates (Ki = 13.6-120.9 nM), and selectively stained the Aβ plaques on brain sections of transgenic mice. Biodistribution in normal mice revealed that [(99m)Tc]5a-d exhibited moderate initial uptake (0.31%-0.49% ID/g at 2 min) and reasonable brain washout at 60 min post-injection. Although additional optimizations are still needed to facilitate it's penetration through BBB, the present results indicate that [(99m)Tc]5a may be a potential SPECT probe for imaging Aβ plaques in Alzheimer's brains.
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synthesis and structure affinity relationships of novel Dibenzylideneacetone derivatives as probes for β amyloid plaques
Journal of Medicinal Chemistry, 2011Co-Authors: Mengchao Cui, Masahiro Ono, Hiroyuki Kimura, Boli Liu, Hideo SajiAbstract:A new and extensive set of Dibenzylideneacetone derivatives was synthesized and screened for affinity toward Aβ1−42 aggregates. Structure−activity relationships revealed the binding of Dibenzylideneacetones to be affected by various substituents. The introduction of a substituent group in the ortho position reduced or abolished the binding. However, the para position was highly tolerant of sterically demanding substitutions. Three radioiodinated ligands (6, 70, and 71) and two 18F fluoro-pegylated (FPEG) ligands (83 and 85) were prepared, all of which displayed high affinity for Aβ1−42 aggregates (Ki ranging from 0.9 to 7.0 nM). In biodistribution experiments, they exhibited good initial penetration (1.59, 4.68, 4.56, 4.13, and 5.15% ID/g, respectively, at 2 min) of and fast clearance from the brain. Autoradiography with sections of postmortem AD brain and transgenic mouse brain confirmed the high affinity of these tracers. These preliminary results strongly suggest the Dibenzylideneacetone structure to b...
Suleyman Gulcemal - One of the best experts on this subject based on the ideXlab platform.
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synthesis characterization and catalytic application of secondary carbene palladium ii complexes obtained by oxidative addition reaction
Inorganica Chimica Acta, 2012Co-Authors: Suleyman Gulcemal, Salih Gunnaz, Jeanclaude Daran, Bekir CetinkayaAbstract:Abstract Three new secondary carbene palladium(II) complexes (1b–3b) were synthesized via oxidative insertion of Pd2(dba)3 (dba = Dibenzylideneacetone) into the C–Cl bond of dialkyl(chloromethylene)ammonium chloride salts ([R2NCHCl]+Cl−). All complexes have been characterized by 1H, 13C, and 31P NMR analysis. X-ray diffraction studies on single crystal of 3b confirm the cis square planar geometry. Complexes (1b–3b) have been proved to be efficient catalysts in the Heck coupling of styrene with 4-bromoacetophenone.
Chunhui Xing - One of the best experts on this subject based on the ideXlab platform.
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Controlled Pd(0)/t‑Bu3P‑Catalyzed Suzuki Cross-Coupling Polymerization of AB-Type Monomers with PhPd(t‑Bu3P)I or Pd2(dba)3/t‑Bu3P/ArI as the Initiator
2016Co-Authors: Honghai Zhang, Chunhui XingAbstract:Controlled Pd(0)/t-Bu3P-catalyzed Suzuki cross-coupling polymerizations of AB-type monomers via the chain-growth mechanism with an ArPd(t-Bu3P)I complex as the initiator are described. ArPd(t-Bu3P)I complexes, either prepurified or generated in situ from Pd2(dba)3/t-Bu3P/ArI (dba = Dibenzylideneacetone) without separation/purification, were found to be efficient initiators in general for the controlled Suzuki cross-coupling polymerization, with narrow polydispersity indexes (PDIs) of 1.13–1.35 being observed. The Pd2(dba)3/t-Bu3P/p-BrC6H4I combination was identified as a highly robust initiator system, with PDIs of ≤1.20 in general and as low as 1.13 being obtained. Higher number-average molecular weights (Mn) were achieved without a significant increase in the PDI (from 1.14 for a polymer with a Mn = 9500 to 1.20 for a polymer with Mn = 31 400) by using a smaller amount of the Pd2(dba)3/t-Bu3P/p-BrC6H4I initiator in the polymerization
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controlled pd 0 t bu3p catalyzed suzuki cross coupling polymerization of ab type monomers with phpd t bu3p i or pd2 dba 3 t bu3p ari as the initiator
Journal of the American Chemical Society, 2012Co-Authors: Honghai Zhang, Chunhui XingAbstract:Controlled Pd(0)/t-Bu3P-catalyzed Suzuki cross-coupling polymerizations of AB-type monomers via the chain-growth mechanism with an ArPd(t-Bu3P)I complex as the initiator are described. ArPd(t-Bu3P)I complexes, either prepurified or generated in situ from Pd2(dba)3/t-Bu3P/ArI (dba = Dibenzylideneacetone) without separation/purification, were found to be efficient initiators in general for the controlled Suzuki cross-coupling polymerization, with narrow polydispersity indexes (PDIs) of 1.13–1.35 being observed. The Pd2(dba)3/t-Bu3P/p-BrC6H4I combination was identified as a highly robust initiator system, with PDIs of ≤1.20 in general and as low as 1.13 being obtained. Higher number-average molecular weights (Mn) were achieved without a significant increase in the PDI (from 1.14 for a polymer with a Mn = 9500 to 1.20 for a polymer with Mn = 31 400) by using a smaller amount of the Pd2(dba)3/t-Bu3P/p-BrC6H4I initiator in the polymerization.