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Ida, Shohei,Ouchi, Makoto,Sawamoto, Mitsuo American Chemical Society 2010 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.132 No.42
<P>Surprisingly high monomer selectivity was demonstrated in competitive radical addition with two kinds of methacrylates carrying sodium and ammonium cation. Crucial is size-specific recognition by a lariat crown ether embedded close to the reactive halide in a designer template initiator. Especially, a combination with an active ruthenium catalyst led to outstanding selectivity at low temperature. This template system will open the way to unprecedented sequence-regulated polymerization.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2010/jacsat.2010.132.issue-42/ja1070575/production/images/medium/ja-2010-070575_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja1070575'>ACS Electronic Supporting Info</A></P>
Ouchi, Makoto,Ito, Makoto,Kamemoto, Satoshi,Sawamoto, Mitsuo Wiley (John WileySons) 2008 Chemistry - An Asian Journal Vol. No.
<P>The systematic search and design of phosphine ligands (PR(3)) and amine cocatalysts resulted in obtaining pentamethyl-cyclopentadienyl (Cp*) ruthenium(II) phosphine complexes [RuCp*Cl(PR(3))(2)], which are highly active and removable catalysts, for transition-metal-catalyzed living radical polymerization of methyl methacrylate (MMA). The catalysts are conveniently prepared in situ from a tetrameric precursor [RuCp*(mu(3)-Cl)](4) and a selected phosphine (PR(3)). The combination of the meta-tolyl phosphine [P(m-Tol)(3)] ligand and a primary diamine cocatalyst [NH(2)(CH(2))(6)NH(2)] provides a highly active catalytic system with precision control of the molecular weight of the polymer. The high activity enables a low catalyst dose and a high turn-over frequency without deteriorating the controllability. A hydrophilic amine cocatalyst (amino alcohol) in place of the diamine, further forms an active and removable catalyst; simple treatment with acidic water gave colorless polymers visually free from metal residues (>97 % removal; <64 ppm).</P>
Ida, Shohei,Terashima, Takaya,Ouchi, Makoto,Sawamoto, Mitsuo American Chemical Society 2009 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.131 No.31
<P>A ruthenium(II)-catalyzed, highly selective, quantitative radical addition of an alkene, methacrylic acid (MAA), has been achieved by using a template halide (2) containing a built-in amine group as a recognition site for the carboxyl group of the substrate. The specific ionic binding of MAA by the amine template (1:1 molar ratio) led to preferential formation of the 1:1 MAA-2 adduct, whereas a similar halide without a template induced MAA oligomerization even in the presence of an externally added amine. A competitive radical addition of MAA versus its ester form [methyl methacrylate (MMA)] on the halide further demonstrated that the substrate selectivity [k'(MAA)/k'(MMA)] for 2 is enhanced more than 10 times by the intramolecular introduction of the template relative to the result for the nontemplate halide. These specificities are most likely triggered by the specific interaction (recognition) of the carboxyl group in MAA via the acid-selective template amine, which is implanted in the close vicinity of the radical addition site in 2. These results intimate possibility of control over the repeat-unit sequence in precision polymerization.</P>