Satoshi Uchino

Bio: Satoshi Uchino is an academic researcher from Tokyo Institute of Technology. The author has contributed to research in topics: Anionic addition polymerization & Living anionic polymerization. The author has an hindex of 4, co-authored 7 publications receiving 39 citations.

Live imaging of transcription sites using an elongating RNA polymerase II-specific probe.

Abstract: In eukaryotic nuclei, most genes are transcribed by RNA polymerase II (RNAP2), whose regulation is a key to understanding the genome and cell function. RNAP2 has a long heptapeptide repeat (Tyr1-Ser2-Pro3-Thr4-Ser5-Pro6-Ser7), and Ser2 is phosphorylated on an elongation form. To detect RNAP2 Ser2 phosphorylation (RNAP2 Ser2ph) in living cells, we developed a genetically encoded modification-specific intracellular antibody (mintbody) probe. The RNAP2 Ser2ph-mintbody exhibited numerous foci, possibly representing transcription "factories," and foci were diminished during mitosis and in a Ser2 kinase inhibitor. An in vitro binding assay using phosphopeptides confirmed the mintbody's specificity. RNAP2 Ser2ph-mintbody foci were colocalized with proteins associated with elongating RNAP2 compared with factors involved in the initiation. These results support the view that mintbody localization represents the sites of RNAP2 Ser2ph in living cells. RNAP2 Ser2ph-mintbody foci showed constrained diffusional motion like chromatin, but they were more mobile than DNA replication domains and p300-enriched foci, suggesting that the elongating RNAP2 complexes are separated from more confined chromatin domains.

Application of ketenes to well-defined polyester synthesis. II. Synthesis of reactive polyester by living anionic polymerization of (4-halophenyl)ethylketene

Abstract: Novel ketenes, (4-chlorophenyl)ethylketene and (4-bromophenyl)ethylketene, were synthesized by dehydrochlorination of 2-(4-halophenyl)butanoyl chlorides, and their anionic polymerizations by lithium (4-methoxyphenoxide) in tetrahydrofuran at −20 °C were carried out to afford the corresponding polyesters with narrow molecular weight distributions (weight-average molecular weight/number-average molecular weight < 1.3) quantitatively. Polymerizations with various feed ratios afforded the corresponding polyesters with predictable molecular weights and narrow molecular weight distributions. Kinetic studies of the polymerizations at −78 °C revealed that the polymerization rates were apparently larger than that of ethylphenylketene, which is considered to be responsible for the enhanced electrophilicities of the monomers via the introduction of electron-negative halogen atoms. Monomer conversion agreed with the first-order kinetic equation. These results strongly support the living mechanism of this polymerization. The obtained polyesters were modified by a palladium-catalyzed coupling reaction of the side-chain 4-halophenyl group with 4-methoxyphenylboronic acid, demonstrating their potential as reactive polymers. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2093–2102, 2001

Living anionic polymerization of ethylphenylketene: A novel approach to well‐defined polyester synthesis

Abstract: A living polymerization of ethylphenylketene (EPK) was accomplished. When polymerization of EPK was carried out with butyllithium as an initiator in tetrahydrofuran (THF) at -20 °C, EPK was completely consumed within 5 min, and the corresponding polyester with narrow molecular weight distribution (M w /M n ∼ 1.1) was obtained almost quantitatively. Kinetic study of the polymerization at -78 °C revealed that conversion of EPK agreed with the first-order kinetic equation, and that M n of the polymer increased in virtually direct proportion to the conversion. Along with these results, successful results in postpolymerization at -20 °C strongly supported living mechanism of the present polymerization. Further, lithium alkoxides having a methoxy group, styryl moiety, and nitroxyl radical, also successfully initiated polymerization of EPK to afford the corresponding polymers having functional initiating ends. In the polymerization with varying feed ratio [EPK] 0 /[initiator] 0 , the linear relationship between the feed ratio and M n of the obtained polymer was observed, while maintaining narrow M w /M n .

Application of ketenes to well-defined polyester synthesis. III. Living anionic polymerization of ethyl(4-methoxyphenyl)ketene—Development of polyester having masked phenol side chain

Abstract: A novel ketene, ethyl(4-methoxyphenyl)ketene (EMPK), was synthesized by the dehydrochlorination of 2-(4-methoxyphenyl)butanoyl chloride. The anionic polymerizations of EMPK by butyllithium in tetrahydrofuran at −20 °C were carried out with a varying feed ratio to give the corresponding polyesters having predictable molecular weights and narrow molecular weight distributions, quantitatively. The selective formation of the polyester was confirmed by IR analysis, and the reductive degradation of the polymer was supported by lithium–aluminium hydride. The second feed of the monomer (after the first stage of polymerization) resulted in the formation of the polymer with the expectedly increased molecular weight and low polydispersity to strongly support the living mechanism of this polymerization. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1596–1600, 2001

A facile route to ketene-functionalized polymers for general materials applications

Abstract: Function matters in materials science, and methodologies that provide paths to multiple functionality in a single step are to be prized. Therefore, we introduce a robust and efficient strategy for exploiting the versatile reactivity of ketenes in polymer chemistry. New monomers for both radical and ring-opening metathesis polymerization have been developed, which take advantage of Meldrum's acid as both a synthetic building block and a thermolytic precursor to dialkyl ketenes. The ketene-functionalized polymers are directly detected by their characteristic infrared absorption and are found to be stable under ambient conditions. The inherent ability of ketenes to provide crosslinking via dimerization and to act as reactive chemical handles via addition, provides simple methodology for application in complex materials challenges. Such versatile characteristics are illustrated by covalently attaching and patterning a dye through microcontact printing. The strategy highlights the significant opportunities afforded by the traditionally neglected ketene functional group in polymer chemistry.

The emerging utility of ketenes in polymer chemistry

Abstract: The continued evolution of functional materials that contribute to pressing societal challenges requires the development of powerful synthetic methodologies in polymer systems. Since their discovery by Staudinger in the early 20th century, the unique chemistry of ketenes have fascinated synthetic chemists and been the driver of revolutionary applications in photolithography, medicinal chemistry, and commodity materials. The versatile chemistry of ketenes, specifically their ability to act as an electrophile and/or undergo cycloaddition reactions, has recently been shown to provide a powerful platform for the design of next-generation materials. This Highlight focuses on the history of ketenes in materials science and their recent renaissance in polymer chemistry, with specific focus being given to methodologies that provide reliable access to this important functional group in polymer systems. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3769–3782

Low-temperature ketene formation in materials chemistry through molecular engineering

Abstract: The thermolysis of Meldrum's acid derivatives has emerged as a powerful methodology to generate ketenes in polymeric structures, but the required high temperatures for ketene formation may reduce its broad applicability. We take a molecular approach toward addressing this limitation by engineering Meldrum's acid derivatives to undergo thermolysis at significantly lower temperatures. Two distinct strategies are presented and a thorough understanding of the molecular interactions governing their reactivity is provided through model compound design and synthesis, crystal structure analysis, and computation of transition structures. The generality of these molecular design principles allows for the generation of ketenes under mild thermal conditions, providing significant opportunities as a comprehensive and wide-ranging tool for controlling reactivity in both chemical and materials science applications.