The Experts below are selected from a list of 234 Experts worldwide ranked by ideXlab platform
Noritaka Chida - One of the best experts on this subject based on the ideXlab platform.
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Copper-catalyzed electrophilic amination using N-Methoxyamines
Organic & biomolecular chemistry, 2016Co-Authors: Yutaro Fukami, Noritaka Chida, Takamasa Wada, Tatsuhiko Meguro, Takaaki SatoAbstract:Copper-catalyzed electrophilic amination of a triarylboroxin using an N-Methoxyamine to give quick access to a variety of anilines was reported. The reaction was especially useful for syntheses of functionalized anilines when combined with our previously reported nucleophilic addition to N-methoxyamides.
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Synthesis of (±)-Lasubine II Using N-Methoxyamines
Chemistry an Asian journal, 2015Co-Authors: Takashi Yokoyama, Takaaki Sato, Yutaro Fukami, Noritaka ChidaAbstract:The synthesis of (±)-lasubine II has been achieved through a three-component allylation capitalizing on the unique properties of N-Methoxyamines. This reaction enabled the installation of all the carbon atoms of lasubine II in a single operation. The N-methoxy group was efficiently used for the subsequent nitrone formation. A single-step cyclization of isoxazolidines or N-Methoxyamines to form functionalized piperidine rings was also developed.
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Two‐Step Synthesis of Multi‐Substituted Amines by Using an N‐Methoxy Group as a Reactivity Control Element.
ChemInform, 2014Co-Authors: Makoto Yoritate, Kenji Shirokane, Takaaki Sato, Tatsuhiko Meguro, Naoya Matsuo, Noritaka ChidaAbstract:The development of a two-step synthesis of multi-substituted N-Methoxyamines from N-methoxyamides is reported in which the N-methoxy group ensures the success in this two-step procedure.
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Concise Synthesis of α-Trisubstituted Amines from Ketones Using N-Methoxyamines.
ChemInform, 2012Co-Authors: Yusuke Kurosaki, Kenji Shirokane, Takeshi Oishi, Takaaki Sato, Noritaka ChidaAbstract:The target products are constructed in a single step from ketones, N-Methoxyamines and allylstannane or trimethylsilyl cyanide.
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Concise Synthesis of α-Trisubstituted Amines from Ketones Using N-Methoxyamines
Organic letters, 2012Co-Authors: Yusuke Kurosaki, Kenji Shirokane, Takeshi Oishi, Takaaki Sato, Noritaka ChidaAbstract:Three-component allylation and cyanation utilizing a ketone and an N-Methoxyamine are reported. The high nucleophilicity of the N-Methoxyamine and high electrophilicity of the corresponding iminium ion enable the concise synthesis of α-trisubstituted amines in a single step.
Takaaki Sato - One of the best experts on this subject based on the ideXlab platform.
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Copper-catalyzed electrophilic amination using N-Methoxyamines
Organic & biomolecular chemistry, 2016Co-Authors: Yutaro Fukami, Noritaka Chida, Takamasa Wada, Tatsuhiko Meguro, Takaaki SatoAbstract:Copper-catalyzed electrophilic amination of a triarylboroxin using an N-Methoxyamine to give quick access to a variety of anilines was reported. The reaction was especially useful for syntheses of functionalized anilines when combined with our previously reported nucleophilic addition to N-methoxyamides.
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Synthesis of (±)-Lasubine II Using N-Methoxyamines
Chemistry an Asian journal, 2015Co-Authors: Takashi Yokoyama, Takaaki Sato, Yutaro Fukami, Noritaka ChidaAbstract:The synthesis of (±)-lasubine II has been achieved through a three-component allylation capitalizing on the unique properties of N-Methoxyamines. This reaction enabled the installation of all the carbon atoms of lasubine II in a single operation. The N-methoxy group was efficiently used for the subsequent nitrone formation. A single-step cyclization of isoxazolidines or N-Methoxyamines to form functionalized piperidine rings was also developed.
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Two‐Step Synthesis of Multi‐Substituted Amines by Using an N‐Methoxy Group as a Reactivity Control Element.
ChemInform, 2014Co-Authors: Makoto Yoritate, Kenji Shirokane, Takaaki Sato, Tatsuhiko Meguro, Naoya Matsuo, Noritaka ChidaAbstract:The development of a two-step synthesis of multi-substituted N-Methoxyamines from N-methoxyamides is reported in which the N-methoxy group ensures the success in this two-step procedure.
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Concise Synthesis of α-Trisubstituted Amines from Ketones Using N-Methoxyamines.
ChemInform, 2012Co-Authors: Yusuke Kurosaki, Kenji Shirokane, Takeshi Oishi, Takaaki Sato, Noritaka ChidaAbstract:The target products are constructed in a single step from ketones, N-Methoxyamines and allylstannane or trimethylsilyl cyanide.
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Concise Synthesis of α-Trisubstituted Amines from Ketones Using N-Methoxyamines
Organic letters, 2012Co-Authors: Yusuke Kurosaki, Kenji Shirokane, Takeshi Oishi, Takaaki Sato, Noritaka ChidaAbstract:Three-component allylation and cyanation utilizing a ketone and an N-Methoxyamine are reported. The high nucleophilicity of the N-Methoxyamine and high electrophilicity of the corresponding iminium ion enable the concise synthesis of α-trisubstituted amines in a single step.
Lili Liu - One of the best experts on this subject based on the ideXlab platform.
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combined treatment with temozolomide and Methoxyamine blocking apurininc pyrimidinic site repair coupled with targeting topoisomerase iiα
Clinical Cancer Research, 2007Co-Authors: Ling Yan, Stanton L. Gerson, Alina Bulgar, Yanling Miao, Varun Mahajan, Jon R. Donze, Lili LiuAbstract:Purpose: Methoxyamine has been shown to potentiate the cytotoxic effect of temozolomide both in vitro and in human tumor xenograft models. We postulate that the enhanced cytotoxicity is mediated by Methoxyamine-bound apurininc/pyrimidinic (MX-AP) site, a key lesion formed by the combination of temozolomide and Methoxyamine. When located within topoisomerase IIα (topo II) cleavage sites in DNA, MX-AP sites act as dual lethal targets, not only functionally disrupting the base excision repair (BER) pathway but also potentially poisoning topo II. Experimental Design: Using oligonucleotide substrates, in which a position-specific MX-AP site is located within topo II cleavage sites, we examined the effect of MX-AP site on both AP endonuclease– and topo II–mediated DNA cleavage in vitro . Results: MX-AP sites were refractory to the catalytic activity of AP endonuclease, indicating their ability to block BER. However, they were cleaved by either purified topo II or nuclear extracts from tumor cells expressing high levels of topo II, suggesting that MX-AP sites stimulate topo II–mediated DNA cleavages. In cells, treatment with temozolomide and Methoxyamine increased the expression of topo II and enriched the formation of γH2AX foci, which were colocalized with up-regulated topo II, confirming that DNA double-strand breaks marked by γH2AX foci are associated with topo II in cells. Conclusions: Our findings identify a molecular mechanism of cell death whereby MX-AP sites that cumulated in cells due to resistance to BER potentially convert topo II into biotoxins, resulting in enzyme-mediated DNA scission and cell death.
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Combined Treatment with Temozolomide and Methoxyamine: Blocking Apurininc/Pyrimidinic Site Repair Coupled with Targeting Topoisomerase IIα
Clinical cancer research : an official journal of the American Association for Cancer Research, 2007Co-Authors: Ling Yan, Stanton L. Gerson, Alina Bulgar, Yanling Miao, Varun Mahajan, Jon R. Donze, Lili LiuAbstract:Purpose: Methoxyamine has been shown to potentiate the cytotoxic effect of temozolomide both in vitro and in human tumor xenograft models. We postulate that the enhanced cytotoxicity is mediated by Methoxyamine-bound apurininc/pyrimidinic (MX-AP) site, a key lesion formed by the combination of temozolomide and Methoxyamine. When located within topoisomerase IIα (topo II) cleavage sites in DNA, MX-AP sites act as dual lethal targets, not only functionally disrupting the base excision repair (BER) pathway but also potentially poisoning topo II. Experimental Design: Using oligonucleotide substrates, in which a position-specific MX-AP site is located within topo II cleavage sites, we examined the effect of MX-AP site on both AP endonuclease– and topo II–mediated DNA cleavage in vitro . Results: MX-AP sites were refractory to the catalytic activity of AP endonuclease, indicating their ability to block BER. However, they were cleaved by either purified topo II or nuclear extracts from tumor cells expressing high levels of topo II, suggesting that MX-AP sites stimulate topo II–mediated DNA cleavages. In cells, treatment with temozolomide and Methoxyamine increased the expression of topo II and enriched the formation of γH2AX foci, which were colocalized with up-regulated topo II, confirming that DNA double-strand breaks marked by γH2AX foci are associated with topo II in cells. Conclusions: Our findings identify a molecular mechanism of cell death whereby MX-AP sites that cumulated in cells due to resistance to BER potentially convert topo II into biotoxins, resulting in enzyme-mediated DNA scission and cell death.
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Measurement of Anti-Cancer Agent Methoxyamine in Plasma by Tandem Mass Spectrometry with On-Line Sample Extraction
Journal of chromatography. B Analytical technologies in the biomedical and life sciences, 2003Co-Authors: Shuming Yang, Lili Liu, Stanton L. GersonAbstract:In this work, we present the development and validation of a tandem mass spectrometry method for the quantitative determination of Methoxyamine (CH3ONH2), a potential new chemotherapeutic agent, in human and mouse plasma. Methoxyamine together with the internal standard (I.S.) methoxyl-D3-amine was directly derivatized in plasma sample with a novel chemical agent 4-(N,N-diethylamino)benzaldehyde. The product solution was injected into an on-line Oasis HLB extraction column (2.1 mm x 20 mm) for analyte extraction. After the elution of extractives, the derivatized analytes were monitored by the positive-electrospray-ionization mass spectrometry (ESI-MS-MS). The structures of derivatized analytes were elucidated by fragmentation. Quantitation of plasma Methoxyamine was carried out by the multiple reaction monitoring (MRM) mode. This method had a linear calibration range of 1.00-1000 ng/ml with a correlation coefficient of 0.9999 for Methoxyamine in both human and mouse plasma. The limit of detection (LOD) and limit of quantification (LOQ) for Methoxyamine in plasma were 0.150 and 0.500 ng/ml, respectively. It was demonstrated that the method had high recovery and accuracy (90.1-94.7 and 90.1-96.3%), as well as excellent intra- and inter-assay precision (2.2 and 3.7%), at three concentration levels (5.00, 50.0, 500 ng/ml). This method has been used to analyze the plasma levels of Methoxyamine in samples obtained from male CD1 mice after bolus intraperitoneal injection of 2, 5 and 20mg Methoxyamine hydrochloride (CH3ONH2.HCl) per kilogram mouse.
Nasuo Ueda - One of the best experts on this subject based on the ideXlab platform.
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A New Method for the Synthesis of β-Amino Acid Derivatives and β-Lactams. Reaction of N-Alkoxycarbonyl-1-Methoxyamines with Esters
The Journal of Organic Chemistry, 1999Co-Authors: Naoki Kise, Nasuo UedaAbstract:The reaction of N-alkoxycarbonyl-1-Methoxyamines with esters is an alternative to the reaction of imines with esters for the synthesis of β-amino acid derivatives. In this reaction, N-alkoxycarbonyl-1-Methoxyamines corresponding to unstable imines can also be employed. Although anti adducts were obtained preferentially in the absence of Ti complexes, the diastereoselectivity of this reaction was reversed by the addition of Ti(OPr-i)4. The obtained adducts were transformed to the corresponding β-lactams.
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Asymmetric Synthesis of anti-α,β-Disubstituted β-Amino Acid Derivatives by Reaction of N-Alkoxycarbonyl-1-Methoxyamines with Optically Active 2-Oxazolidinones
Organic Letters, 1999Co-Authors: Naoki Kise And, Nasuo UedaAbstract:The reaction of N-alkoxycarbonyl-1-Methoxyamines and (4S)-3-butyryl-4-isopropyl-2-oxazolidinone afforded the corresponding adducts with anti selectively (60% de). Both anti- and syn-α,β-disubstitut...
Naoki Kise - One of the best experts on this subject based on the ideXlab platform.
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A New Method for the Synthesis of β-Amino Acid Derivatives and β-Lactams. Reaction of N-Alkoxycarbonyl-1-Methoxyamines with Esters
The Journal of Organic Chemistry, 1999Co-Authors: Naoki Kise, Nasuo UedaAbstract:The reaction of N-alkoxycarbonyl-1-Methoxyamines with esters is an alternative to the reaction of imines with esters for the synthesis of β-amino acid derivatives. In this reaction, N-alkoxycarbonyl-1-Methoxyamines corresponding to unstable imines can also be employed. Although anti adducts were obtained preferentially in the absence of Ti complexes, the diastereoselectivity of this reaction was reversed by the addition of Ti(OPr-i)4. The obtained adducts were transformed to the corresponding β-lactams.
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Reaction of N-acyl-α-Methoxyamines with organozinc reagents. A convenient method for the synthesis of homoallylamines and β-amino esters
Tetrahedron Letters, 1994Co-Authors: Naoki Kise, Hiroki Yamazaki, Toshirou Mabuchi, Tatsuya ShonoAbstract:The reaction of N-acyl-α-Methoxyamines with allyl-, propargyl-, and benzylzinc bromides and Reformatsky reagents proceeds in THF at room temperature. Homoallyl- and homopropargylamines and β-amino esters are synthesized in good yields.
