The Experts below are selected from a list of 2325 Experts worldwide ranked by ideXlab platform
Keiji Maruoka - One of the best experts on this subject based on the ideXlab platform.
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enantioselective alkylation of n diphenylmethylene glycinate tert butyl ester synthesis of r 2 benzhydrylidenamino 3 phenylpropanoic acid tert butyl ester
Organic Syntheses, 2014Co-Authors: Seiji Shirakawa, Kenichiro Yamamoto, Kun Liu, Keiji MaruokaAbstract:N-(Diphenylmethylene)Glycine tert-butyl ester Benzyl bromide Toluene Potassium hydroxide (S)-4,4-Dibutyl-2,6-bis(3,4,5-trifluorophenyl)-4,5-dihydro-3H-dinaphtho[2,1-c:1',2'-e]azepinium bromide (R)-2-(Benzhydrylidenamino)-3-phenylpropanoic acid tert-butyl ester Keywords: Enantioselective alkylation; N-(diphenylmethylene)glycinate tert-butyl ester; (R)-2-(benzhydrylidenamino)-3-phenylpropanoic acid tert-butyl ester; Chiral phase-transfer catalysts; Glycine Derivative
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design of binaphthyl modified symmetrical chiral phase transfer catalysts substituent effect of 4 4 6 6 positions of binaphthyl rings in the asymmetric alkylation of a Glycine Derivative
Chemistry-an Asian Journal, 2007Co-Authors: Seiji Shirakawa, Youhei Tanaka, Mitsuhiro Ueda, Takuya Hashimoto, Keiji MaruokaAbstract:A series of symmetrical chiral phase-transfer catalysts with 4,4',6,6'-tetrasubstituted binaphthyl units have been designed, and these aryl- and trialkylsilyl-substituted phase-transfer catalysts, which included a highly fluorinated catalyst, were prepared. The chiral efficiency of these chiral phase-transfer catalysts was investigated in the asymmetric alkylation of tert-butylglycinate-benzophenone Schiff base under mild phase-transfer conditions, and the eminent substituent effect of the 4,4',6,6'-positions of the binaphthyl units on enantioselection was observed. In particular, the OctMe2Si-substituted catalyst was found to be highly efficient for the phase-transfer alkylation of tert-butylglycinate-benzophenone Schiff base with various alkyl halides, including sec-alkyl halides. The highly fluorinated catalyst was also utilized as a recyclable chiral phase-transfer catalyst by simple extraction with fluorous solvents.
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development of a recyclable fluorous chiral phase transfer catalyst application to the catalytic asymmetric synthesis of α amino acids
Organic Letters, 2004Co-Authors: Seiji Shirakawa, Youhei Tanaka, Keiji MaruokaAbstract:A recyclable fluorous chiral phase-transfer catalyst was synthesized and successfully applied for the catalytic asymmetric synthesis of both natural and unnatural α-amino acids. The reaction involves alkylation of a Glycine Derivative followed by extractive recovery of the chiral phase-transfer catalyst using fluorous solvent.
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evaluation of the efficiency of the chiral quaternary ammonium salt β np nas br in the organic aqueous phase transfer alkylation of a protected Glycine Derivative
Advanced Synthesis & Catalysis, 2002Co-Authors: Takashi Ooi, Yukitaka Uematsu, Keiji MaruokaAbstract:The inherent efficiency of the N-spiro C2-symmetric chiral quaternary ammonium salt (S,S)-3 [(S,S)-β-Np-NAS-Br] has been evaluated in the representative organic-aqueous liquid-liquid phase-transfer benzylation and allylation of Glycine tert-butyl ester benzophenone Schiff base (1). This revealed the practical conditions for the asymmetric synthesis of both natural and unnatural α-amino acids, whose usefulness was demonstrated by the formal enantioselective synthesis of antibiotic L-azatyrosine.
Maciej Serda - One of the best experts on this subject based on the ideXlab platform.
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a 60 fullerene nanoconjugate with gemcitabine synthesis biophysical properties and biological evaluation for treating pancreatic cancer
Cancer Nanotechnology, 2020Co-Authors: Pawel Nalepa, Robert Gawecki, Grzegorz Szewczyk, Katarzyna Balin, Mateusz Dulski, Mieczyslaw Sajewicz, Anna Mrozekwilczkiewicz, Robert Musiol, Jaroslaw Polanski, Maciej SerdaAbstract:The first-line chemotherapy drug that is used to treat pancreatic ductal adenocarcinoma is gemcitabine. Unfortunately, its effectiveness is hampered by its chemo-resistance, low vascularization and drug biodistribution limitations in the tumor microenvironment. Novel nanotherapeutics must be developed in order to improve the prognosis for patients with pancreatic cancer. We developed a synthetic methodology for obtaining a water-soluble nanoconjugate of a [60]fullerene-Glycine Derivative with the FDA-approved drug gemcitabine (nanoC60GEM). The proposed synthetic protocol enables a highly water-soluble [60]fullerene-Glycine Derivative (6) to be obtained, which was next successfully conjugated with gemcitabine using the EDCI/NHS carbodiimide protocol. The desired nanoconjugate was characterized using mass spectrometry and DLS, IR and XPS techniques. The photogeneration of singlet oxygen and the superoxide anion radical were studied by measuring 1O2 near-infrared luminescence at 1270 nm, followed by spin trapping of the DMPO adducts by EPR spectroscopy. The biological assays that were performed indicate that there is an inhibition of the cell cycle in the S phase and the induction of apoptosis by nanoC60GEM. In this paper, we present a robust approach for synthesizing a highly water-soluble [60]fullerene nanoconjugate with gemcitabine. The performed biological assays on pancreatic cancer cell lines demonstrated cytotoxic effects of nanoC60GEM, which were enhanced by the generation of reactive oxygen species after blue LED irradiation of synthesized fullerene nanomaterial.
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A [60]fullerene nanoconjugate with gemcitabine: synthesis, biophysical properties and biological evaluation for treating pancreatic cancer
Cancer Nanotechnology, 2020Co-Authors: Paweł Nalepa, Robert Gawecki, Grzegorz Szewczyk, Katarzyna Balin, Mateusz Dulski, Mieczyslaw Sajewicz, Jaroslaw Polanski, Anna Mrozek-wilczkiewicz, Robert Musioł, Maciej SerdaAbstract:Background The first-line chemotherapy drug that is used to treat pancreatic ductal adenocarcinoma is gemcitabine. Unfortunately, its effectiveness is hampered by its chemo-resistance, low vascularization and drug biodistribution limitations in the tumor microenvironment. Novel nanotherapeutics must be developed in order to improve the prognosis for patients with pancreatic cancer. Results We developed a synthetic methodology for obtaining a water-soluble nanoconjugate of a [60]fullerene-Glycine Derivative with the FDA-approved drug gemcitabine ( nanoC _ 60 GEM) . The proposed synthetic protocol enables a highly water-soluble [60]fullerene-Glycine Derivative (6) to be obtained, which was next successfully conjugated with gemcitabine using the EDCI/NHS carbodiimide protocol. The desired nanoconjugate was characterized using mass spectrometry and DLS, IR and XPS techniques. The photogeneration of singlet oxygen and the superoxide anion radical were studied by measuring ^1O_2 near-infrared luminescence at 1270 nm, followed by spin trapping of the DMPO adducts by EPR spectroscopy. The biological assays that were performed indicate that there is an inhibition of the cell cycle in the S phase and the induction of apoptosis by nanoC_60GEM. Conclusion In this paper, we present a robust approach for synthesizing a highly water-soluble [60]fullerene nanoconjugate with gemcitabine. The performed biological assays on pancreatic cancer cell lines demonstrated cytotoxic effects of nanoC_60GEM, which were enhanced by the generation of reactive oxygen species after blue LED irradiation of synthesized fullerene nanomaterial.
Seiji Shirakawa - One of the best experts on this subject based on the ideXlab platform.
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enantioselective alkylation of n diphenylmethylene glycinate tert butyl ester synthesis of r 2 benzhydrylidenamino 3 phenylpropanoic acid tert butyl ester
Organic Syntheses, 2014Co-Authors: Seiji Shirakawa, Kenichiro Yamamoto, Kun Liu, Keiji MaruokaAbstract:N-(Diphenylmethylene)Glycine tert-butyl ester Benzyl bromide Toluene Potassium hydroxide (S)-4,4-Dibutyl-2,6-bis(3,4,5-trifluorophenyl)-4,5-dihydro-3H-dinaphtho[2,1-c:1',2'-e]azepinium bromide (R)-2-(Benzhydrylidenamino)-3-phenylpropanoic acid tert-butyl ester Keywords: Enantioselective alkylation; N-(diphenylmethylene)glycinate tert-butyl ester; (R)-2-(benzhydrylidenamino)-3-phenylpropanoic acid tert-butyl ester; Chiral phase-transfer catalysts; Glycine Derivative
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design of binaphthyl modified symmetrical chiral phase transfer catalysts substituent effect of 4 4 6 6 positions of binaphthyl rings in the asymmetric alkylation of a Glycine Derivative
Chemistry-an Asian Journal, 2007Co-Authors: Seiji Shirakawa, Youhei Tanaka, Mitsuhiro Ueda, Takuya Hashimoto, Keiji MaruokaAbstract:A series of symmetrical chiral phase-transfer catalysts with 4,4',6,6'-tetrasubstituted binaphthyl units have been designed, and these aryl- and trialkylsilyl-substituted phase-transfer catalysts, which included a highly fluorinated catalyst, were prepared. The chiral efficiency of these chiral phase-transfer catalysts was investigated in the asymmetric alkylation of tert-butylglycinate-benzophenone Schiff base under mild phase-transfer conditions, and the eminent substituent effect of the 4,4',6,6'-positions of the binaphthyl units on enantioselection was observed. In particular, the OctMe2Si-substituted catalyst was found to be highly efficient for the phase-transfer alkylation of tert-butylglycinate-benzophenone Schiff base with various alkyl halides, including sec-alkyl halides. The highly fluorinated catalyst was also utilized as a recyclable chiral phase-transfer catalyst by simple extraction with fluorous solvents.
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development of a recyclable fluorous chiral phase transfer catalyst application to the catalytic asymmetric synthesis of α amino acids
Organic Letters, 2004Co-Authors: Seiji Shirakawa, Youhei Tanaka, Keiji MaruokaAbstract:A recyclable fluorous chiral phase-transfer catalyst was synthesized and successfully applied for the catalytic asymmetric synthesis of both natural and unnatural α-amino acids. The reaction involves alkylation of a Glycine Derivative followed by extractive recovery of the chiral phase-transfer catalyst using fluorous solvent.
Hweihsien Chen - One of the best experts on this subject based on the ideXlab platform.
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effects of sarcosine and n n dimethylGlycine on nmda receptor mediated excitatory field potentials
Journal of Biomedical Science, 2017Co-Authors: Yishu Tu, Yufeng J Tseng, Minghuan Chan, Hweihsien ChenAbstract:Sarcosine, a Glycine transporter type 1 inhibitor and an N-methyl-D-aspartate (NMDA) receptor co-agonist at the Glycine binding site, potentiates NMDA receptor function. Structurally similar to sarcosine, N,N-dimethylGlycine (DMG) is also N-methyl Glycine-Derivative amino acid and commonly used as a dietary supplement. The present study compared the effects of sarcosine and DMG on NMDA receptor-mediated excitatory field potentials (EFPs) in mouse medial prefrontal cortex brain slices using a multi-electrode array system. Glycine, sarcosine and DMG alone did not alter the NMDA receptor-mediated EFPs, but in combination with glutamate, Glycine and its N-methyl Derivatives significantly increased the frequency and amplitude of EFPs. The enhancing effects of Glycine analogs in combination with glutamate on EFPs were remarkably reduced by the Glycine binding site antagonist 7-chlorokynurenate (7-CK). However, DMG, but not sarcosine, reduced the frequency and amplitude of EFPs elicited by co-application of glutamate plus Glycine. D-cycloserine, a partial agonist at the Glycine binding site on NMDA receptors, affected EFPs in a similar manner to DMG. Furthermore, DMG, but not sarcosine, reduced the frequencies and amplitudes of EFPs elicited by glutamate plus D-serine, another endogenous ligand for Glycine binding site. These findings suggest that sarcosine acts as a full agonist, yet DMG is a partial agonist at Glycine binding site of NMDA receptors. The molecular docking analysis indicated that the interactions of Glycine, sarcosine, and DMG to NMDA receptors are highly similar, supporting that the Glycine binding site of NMDA receptors is a critical target site for sarcosine and DMG.
Jaroslaw Polanski - One of the best experts on this subject based on the ideXlab platform.
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a 60 fullerene nanoconjugate with gemcitabine synthesis biophysical properties and biological evaluation for treating pancreatic cancer
Cancer Nanotechnology, 2020Co-Authors: Pawel Nalepa, Robert Gawecki, Grzegorz Szewczyk, Katarzyna Balin, Mateusz Dulski, Mieczyslaw Sajewicz, Anna Mrozekwilczkiewicz, Robert Musiol, Jaroslaw Polanski, Maciej SerdaAbstract:The first-line chemotherapy drug that is used to treat pancreatic ductal adenocarcinoma is gemcitabine. Unfortunately, its effectiveness is hampered by its chemo-resistance, low vascularization and drug biodistribution limitations in the tumor microenvironment. Novel nanotherapeutics must be developed in order to improve the prognosis for patients with pancreatic cancer. We developed a synthetic methodology for obtaining a water-soluble nanoconjugate of a [60]fullerene-Glycine Derivative with the FDA-approved drug gemcitabine (nanoC60GEM). The proposed synthetic protocol enables a highly water-soluble [60]fullerene-Glycine Derivative (6) to be obtained, which was next successfully conjugated with gemcitabine using the EDCI/NHS carbodiimide protocol. The desired nanoconjugate was characterized using mass spectrometry and DLS, IR and XPS techniques. The photogeneration of singlet oxygen and the superoxide anion radical were studied by measuring 1O2 near-infrared luminescence at 1270 nm, followed by spin trapping of the DMPO adducts by EPR spectroscopy. The biological assays that were performed indicate that there is an inhibition of the cell cycle in the S phase and the induction of apoptosis by nanoC60GEM. In this paper, we present a robust approach for synthesizing a highly water-soluble [60]fullerene nanoconjugate with gemcitabine. The performed biological assays on pancreatic cancer cell lines demonstrated cytotoxic effects of nanoC60GEM, which were enhanced by the generation of reactive oxygen species after blue LED irradiation of synthesized fullerene nanomaterial.
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A [60]fullerene nanoconjugate with gemcitabine: synthesis, biophysical properties and biological evaluation for treating pancreatic cancer
Cancer Nanotechnology, 2020Co-Authors: Paweł Nalepa, Robert Gawecki, Grzegorz Szewczyk, Katarzyna Balin, Mateusz Dulski, Mieczyslaw Sajewicz, Jaroslaw Polanski, Anna Mrozek-wilczkiewicz, Robert Musioł, Maciej SerdaAbstract:Background The first-line chemotherapy drug that is used to treat pancreatic ductal adenocarcinoma is gemcitabine. Unfortunately, its effectiveness is hampered by its chemo-resistance, low vascularization and drug biodistribution limitations in the tumor microenvironment. Novel nanotherapeutics must be developed in order to improve the prognosis for patients with pancreatic cancer. Results We developed a synthetic methodology for obtaining a water-soluble nanoconjugate of a [60]fullerene-Glycine Derivative with the FDA-approved drug gemcitabine ( nanoC _ 60 GEM) . The proposed synthetic protocol enables a highly water-soluble [60]fullerene-Glycine Derivative (6) to be obtained, which was next successfully conjugated with gemcitabine using the EDCI/NHS carbodiimide protocol. The desired nanoconjugate was characterized using mass spectrometry and DLS, IR and XPS techniques. The photogeneration of singlet oxygen and the superoxide anion radical were studied by measuring ^1O_2 near-infrared luminescence at 1270 nm, followed by spin trapping of the DMPO adducts by EPR spectroscopy. The biological assays that were performed indicate that there is an inhibition of the cell cycle in the S phase and the induction of apoptosis by nanoC_60GEM. Conclusion In this paper, we present a robust approach for synthesizing a highly water-soluble [60]fullerene nanoconjugate with gemcitabine. The performed biological assays on pancreatic cancer cell lines demonstrated cytotoxic effects of nanoC_60GEM, which were enhanced by the generation of reactive oxygen species after blue LED irradiation of synthesized fullerene nanomaterial.