The Experts below are selected from a list of 3876 Experts worldwide ranked by ideXlab platform
Shu Kobayashi - One of the best experts on this subject based on the ideXlab platform.
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catalytic asymmetric Hydroxymethylation of silicon enolates using an aqueous solution of formaldehyde with a chiral scandium complex
Journal of the American Chemical Society, 2004Co-Authors: Shunpei Ishikawa, Kei Manabe, Tomoaki Hamada, Shu KobayashiAbstract:Catalytic asymmetric Hydroxymethylation of silicon enolates has been achieved. In this reaction, an aqueous solution of formaldehyde can be used to realize an easy and safe procedure, and high enantioselectivities have been obtained. This is the first example of catalytic asymmetric reactions in aqueous media with a chiral scandium complex.
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lewis acid catalyzed asymmetric Hydroxymethylation of silicon enolates in aqueous media
Tetrahedron, 2003Co-Authors: Kei Manabe, Shunpei Ishikawa, Tomoaki Hamada, Shu KobayashiAbstract:Asymmetric Hydroxymethylation of silicon enolates with formaldehyde in aqueous media has been achieved using praseodymium triflate and a chiral crown ether. Formaldehyde aqueous solution can be directly used for the reactions, and a water/THF mixture was found to be the best solvent system. This is the first example of catalytic asymmetric Hydroxymethylation of silicon enolates.
Ryan Mackle - One of the best experts on this subject based on the ideXlab platform.
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Carreira Alkynylations with Paraformaldehyde. A Mild and Convenient Protocol for the Hydroxymethylation of Complex Base-Sensitive Terminal Acetylenes via Alkynylzinc Triflates
2015Co-Authors: Karl J. Hale, Ziyue Xiong, Liping Wang, Soraya Manaviazar, Ryan MackleAbstract:A new synthetic protocol for the Hydroxymethylation of terminal acetylenes is described that involves stoichiometric Carreira alkynylation with solid paraformaldehyde (HO[CH2O]nH) in PhMe at 60 °C. Significantly, the method can be successfully applied on acetylenes that possess base-sensitive ester functionality and heterocyclic rings that readily undergo metalation. While N-methylephedrine (NME) is generally the best Zn(OTf)2-coordinating ligand for promoting Hydroxymethylation, TMEDA can serve as a replacement
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Carreira alkynylations with paraformaldehyde. a mild and convenient protocol for the Hydroxymethylation of complex base-sensitive terminal acetylenes via alkynylzinc triflates.
Organic letters, 2014Co-Authors: Karl J. Hale, Ziyue Xiong, Liping Wang, Soraya Manaviazar, Ryan MackleAbstract:A new synthetic protocol for the Hydroxymethylation of terminal acetylenes is described that involves stoichiometric Carreira alkynylation with solid paraformaldehyde (HO[CH2O]nH) in PhMe at 60 °C. Significantly, the method can be successfully applied on acetylenes that possess base-sensitive ester functionality and heterocyclic rings that readily undergo metalation. While N-methylephedrine (NME) is generally the best Zn(OTf)2-coordinating ligand for promoting Hydroxymethylation, TMEDA can serve as a replacement.
Jian Zhou - One of the best experts on this subject based on the ideXlab platform.
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Hydroxymethylation of α substituted nitroacetates
ChemInform, 2012Co-Authors: Yunlin Liu, Zhongyan Cao, Yiyu Zhang, Jian ZhouAbstract:A highly efficient procedure becomes possible by the use of paraformaldehyde under conditions A).
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Hydroxymethylation of α substituted nitroacetates
Tetrahedron Letters, 2011Co-Authors: Yunlin Liu, Zhongyan Cao, Yiyu Zhang, Jian ZhouAbstract:Abstract Only 1 mol % of K 3 PO 4 is efficient enough to catalyze the Hydroxymethylation of α-substituted nitroacetates in good to excellent yield. Both aliphatic and aryl substituted nitroacetates work well under this reaction. The first catalytic asymmetric version of this reaction also reported that 10 mol % of cupreidine could catalyze this reaction up to 71% ee and 89% yield. Paraformaldehyde and formalin could both serve as the Hydroxymethylation C1 unit. The synthetic application of products is also demonstrated.
Jean Lud Cadet - One of the best experts on this subject based on the ideXlab platform.
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methamphetamine induces tet1 and tet3 dependent dna Hydroxymethylation of crh and avp genes in the rat nucleus accumbens
Molecular Neurobiology, 2018Co-Authors: Subramaniam Jayanthi, Bruce Ladenheim, Michael T Mccoy, Jean Lud Cadet, Betina Gonzalez, Veronica BisagnoAbstract:Methamphetamine (METH) addiction is a biopsychosocial disorder that is accompanied by multiple relapses even after prolonged abstinence, suggesting the possibilities of long-lasting maladaptive epigenetic changes in the brain. Here, we show that METH administration produced time-dependent increases in the expression of corticotropin-releasing hormone (Crh/Crf), arginine vasopressin (Avp), and cocaine- and amphetamine-regulated transcript prepropeptide (Cartpt) mRNAs in the rat nucleus accumbens (NAc). Chromatin immunoprecipitation (ChIP) assays revealed that METH increased the abundance of phosphorylated CREB (pCREB) at the promoter of Cartpt but not at Avp or Crh DNA sequences. In contrast, METH produced DNA hypomethylation at sites near the Crh transcription start site (TSS) and at intragenic Avp sequences. METH also increased DNA Hydroxymethylation at the Crh TSS and at intragenic Avp sites. In addition, METH increased the protein expression of ten-eleven-translocation enzymes that catalyze DNA Hydroxymethylation. Importantly, METH increased TET1 binding at the Crh promoter and increased TET3 binding at Avp intragenic regions. We further tested the role of TET enzymes in METH-induced changes in gene expression by using the TET inhibitor, 1,5-isoquinolinediol (IQD), and found that IQD blocked METH-induced increases in Crh and Avp mRNA expression. Together, these results indicate that METH produced changes in neuropeptide transcription by both activation of the cAMP/CREB pathway and stimulation of TET-dependent DNA Hydroxymethylation. These results provide molecular evidence for epigenetic controls of METH-induced changes in the expression of neuropeptides.
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genome wide dna Hydroxymethylation identifies potassium channels in the nucleus accumbens as discriminators of methamphetamine addiction and abstinence
Molecular Psychiatry, 2017Co-Authors: Jean Lud Cadet, Christie Brannock, Irina N Krasnova, Subramaniam Jayanthi, Bruce Ladenheim, Michael T Mccoy, Donna Walther, Andrea Godino, Mehdi PiroozniaAbstract:Epigenetic consequences of exposure to psychostimulants are substantial but the relationship of these changes to compulsive drug taking and abstinence is not clear. Here, we used a paradigm that helped to segregate rats that reduce or stop their methamphetamine (METH) intake (nonaddicted) from those that continue to take the drug compulsively (addicted) in the presence of footshocks. We used that model to investigate potential alterations in global DNA Hydroxymethylation in the nucleus accumbens (NAc) because neuroplastic changes in the NAc may participate in the development and maintenance of drug-taking behaviors. We found that METH-addicted rats did indeed show differential DNA Hydroxymethylation in comparison with both control and nonaddicted rats. Nonaddicted rats also showed differences from control rats. Differential DNA Hydroxymethylation observed in addicted rats occurred mostly at intergenic sites located on long and short interspersed elements. Interestingly, differentially hydroxymethylated regions in genes encoding voltage (Kv1.1, Kv1.2, Kvb1 and Kv2.2)- and calcium (Kcnma1, Kcnn1 and Kcnn2)-gated potassium channels observed in the NAc of nonaddicted rats were accompanied by increased mRNA levels of these potassium channels when compared with mRNA expression in METH-addicted rats. These observations indicate that changes in differentially hydroxymethylated regions and increased expression of specific potassium channels in the NAc may promote abstinence from drug-taking behaviors. Thus, activation of specific subclasses of voltage- and/or calcium-gated potassium channels may provide an important approach to the beneficial treatment for METH addiction.
Lak Shin Jeong - One of the best experts on this subject based on the ideXlab platform.
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stereoselective synthesis of homo apioneplanocin a as potential inhibitor of s adenosylhomocysteine hydrolase
Nucleosides Nucleotides & Nucleic Acids, 2007Co-Authors: Moon Woo Chun, Hyung Ryong Moon, Hyuk Woo Lee, Jinhee Kim, Hea Ok Kim, Kang Man Lee, Shantanu Pal, Lak Shin JeongAbstract:Homo-apioneplanocin A (1) as a potential inhibitor of S-adenosylhomocysteine hydrolase was synthesized from D-ribose, employing stereoselective Hydroxymethylation, regioselective oxidation, and regio- and chemoselective hydroboration as key steps.
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A highly efficient synthesis of unnatural l-sugars from d-ribose
Tetrahedron Letters, 2005Co-Authors: Hyung Ryong Moon, Won-jun Choi, Chul-seung Park, Lak Shin JeongAbstract:A preparative and short synthesis of l-ribose and l-apiose was accomplished starting from d-ribose via stereoselective cis-dihydroxylation and C2-Hydroxymethylation, respectively. These l-sugars can serve as versatile intermediates for the synthesis of l-nucleosides.
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Synthesis of apio analogues of neplanocin A as potential inhibitors of S-adenosylhomocysteine hydrolase.
Nucleic Acids Symposium Series, 2003Co-Authors: Won-jun Choi, Hyung Ryong Moon, Lak Shin JeongAbstract:Stereoselective synthesis of apio-neplanocin A and its related purine nucleosides which combined the properties of neplanocin A and apio nucleoside was achieved, starting from D-ribose via regioselective Hydroxymethylation and ring-closing metathesis (RCM) as key steps. However, all synthesized compounds did not show significant inhibitory activity against S-adenosylhomocysteine hydrolase, unlike neplanocin A
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stereoselective synthesis of a novel apio analogue of neplanocin a as potential s adenosylhomocysteine hydrolase inhibitor
Organic Letters, 2002Co-Authors: Hyung Ryong Moon, Moon Woo Chun, Lak Shin JeongAbstract:A total synthesis of apio-neplanocin A, which combines properties of apio nucleoside and neplanocin A and is a potential inhibitor of S-adenosylhomocysteine hydrolase, was accomplished starting from d-ribose via stereoselective Hydroxymethylation and RCM reaction.
