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Yutaka Watanabe Shoichiro Ozaki 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4)
Abstract Chemical synthesis of inositol phosphates which are involved in a newly discovered intracellular transduction system is required. For this purpose, phosphorylation is a crucial step. However, phosphorylation of inositol derivatives which involve vicinally situated hydroxyl functions is quite difficult because of steric crowdness and easy formation of cyclic phosphate. This problem was solved by the following two methods. One method consists of the reaction of an inositol derivative with butyllithium and tetrabenzyl pyrophosphate. By this reaction, various inositol polyphosphates were obtained in good yields. The other involves a new phosphitylating agent, 2-diethylamino-1,3,2-benzodioxaphosphepine. Thus, inositols were first treated with the phosphoramidite in the presence of tetrazole and the resulting phosphites were oxidized by mCPBA to give the corresponding phosphates in excellent yields. 相似文献
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Dr. Takahito Watanabe Yumi Kasai Prof. Dr. Hiromi Tobita 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(59):13491-13495
Reaction of N-heterocyclic carbene (NHC)-stabilized PGeP-type germylene Ge{o-(PiPr2)C6H4}2⋅MeIiPr ( 1 ) (MeIiPr=1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) with Ni(cod)2 gave pincer germylene complex Ni[Ge{o-(PiPr2)C6H4}2](MeIiPr) ( 2 ), in which the Ge center of 2 is significantly pyramidalized. Theoretical calculation on 2 predicted the ambiphilicity of the germanium center, which was confirmed by reactivity studies. Thus, complex 2 reacted with both Lewis base MeIMe (MeIMe=1,3,4,5-tetramethylimidazol-2-ylidene) and Lewis acid BH3⋅SMe2 at the germanium center to afford the adducts Ni[Ge{o-(PiPr2)C6H4}2⋅MeIMe](MeIiPr) ( 3 ) and Ni[Ge{o-(PiPr2)C6H4}2⋅BH3](MeIiPr) ( 4 ), respectively. Furthermore, the former was slowly converted to dinuclear complex Ni2[Ge{o-(PiPr2)C6H4}2]2(MeIMe)2 ( 5 ) at room temperature. Complex 5 can be regarded as a dimer of the MeIMe analog of 2 with a Ni-Ge-Ge-Ni linkage. 相似文献
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γ,δ-Epoxy tin compounds underwent divergent reactions depending upon the substitution pattern of the substrates as well as upon Lewis acids used as the indueer. 相似文献
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Kimitsuna Watanabe 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2010,86(1):11-39
In animal mitochondria, several codons are non-universal and their meanings differ depending on the species. In addition, the tRNA structures that decipher codons are sometimes unusually truncated. These features seem to be related to the shortening of mitochondrial (mt) genomes, which occurred during the evolution of mitochondria. These organelles probably originated from the endosymbiosis of an aerobic eubacterium into an ancestral eukaryote. It is plausible that these events brought about the various characteristic features of animal mt translation systems, such as genetic code variations, unusually truncated tRNA and rRNA structures, unilateral tRNA recognition mechanisms by aminoacyl-tRNA synthetases, elongation factors and ribosomes, and compensation for RNA deficits by enlarged proteins. In this article, we discuss molecular mechanisms for these phenomena. Finally, we describe human mt diseases that are caused by modification defects in mt tRNAs. 相似文献
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H. Matsuoka Y. Watanabe M. Maeda T. Kawakami Y. Kubota 《Physica C: Superconductivity and its Applications》2009,469(15-20):1189-1191
We fabricated MgB2 bulks by an in situ Mg diffusive reaction method from compacted B and compacted mixtures of Mg and B respectively. All samples were sintered at 1100 °C for 2 h. MgO impurity phase, density, and critical current density (Jc) were found to be dependent of the starting amount of mixing Mg powder. We also found that the MgO formation in MgB2 matrix was not mainly attributed to the starting amount of additional Mg powder for Mg diffusive reaction. This indicates that MgO presented in the starting Mg powder is hardly diffused into compacted B. 相似文献