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We are engaged in three major areas of research as for new methodologies for catalytic asymmetric synthesis, highly sensitive immunoassay and natural products chemistry.

Development of enantioselective catalysts for carbene transfer and various bond forming reactions:

Fig. 1 Ru(II)-Pheox catalyzed cyclopropanations
Fig.1 Ru(Ⅱ)-Pheox catalyzed

These newly designed chiral ligands, a series of chiral bis(oxazolinyl)pyridine and phenyl oxazolines (Pheox) derivatives and their transition metal complexes can be used to efficiently synthesize bioactive organic compounds which are useful for further stereoselective transformations. Especially, Ru(Ⅱ)-Pheox and its microporous polymer supported complex are found to be a powerful chiral catalyst for carbene transfer reactions to synthesize optically active cyclopropane moiety. (Fig.1) We are also pursuing applications of the newly developed methods for the synthesis of biologically relevant molecules.

Development of a monoclonal antibody-based immunoassay

Fig.2 New immunochromatographic assay kits

Fig.2 New immunochromatographic
assay kits

We have developed a enzyme-linked immunosorbent assay(ELISA) system based on a monoclonal antibody (MoA) to detect small toxic molecule such as pesticide in environment, lombining with synthetic organic chemistry and molecular biology. The working range was 0.3 ng/mL level. This device is now commercially available.
Recently, we developed new immunochromatographic assay kits for analyzing pesticide residues in agricultural products. (Fig.2) The kits are useful for inspection of pesticide residues, which have some advantages such as easy handling, simple operation, high sensitivity, high mobility, rapid analysis, and cost effective compare to modern analytical  instruments.

Natural product chemistry

Other areas of our research interests are, natural products chemistry including extraction, purification (Melaleuca essential oil, VN, etc.), and total synthesis of bioactive natural products(DCG-IV, dysibetaine CPa, strychnine etc.), collaborating with southern Asian countries.

Selected Papers:

  • Le T. L. C.; Suharto, A.; Chanthamath, S.; Shibatomi, K.;Iwasa, S. "Catalytic Asymmetric Intermolecular Cyclopropanation of Diazoketones with Olefins by Using Novel Ru(II)-Pheox Complex", Advances Synthesis & Catalysts, 2019, DOI:org/10.1002/adsc.201801077.
  • Hamada S. A. M.; Nakagawa, Y.; Tone, M.; Inoue, H.; Otog, N.; Fujisawa, I.; Chanthamath, S.; Iwasa, S."Water−Soluble Chiral Ru(II)−Amm−Pheox Catalyst: Reusable and Highly Enantioselective Catalyst for Intramolecular Cyclopropanation of Diazo ester and Weinreb Amide Derivatives" Beilstein Journal of Organic Chemistry, 2019,. accepted.
  • Nakagawa, Y.; Nakayama, N.; Goto, H.; Fujisawa, I.; Chanthamath, S.; Shibatomi, K.; Iwasa, S. "Computational Chemical Analysis for Ru(II)-Pheox Catalyzed Enantioselective Intramolecular Cyclopropanations" Chirality, 2019, 31, [52-61]. DOI:10.1002/chir.23033. (Open access)
  • Tone, M.; Nakagawa, Y.; Chanthamath, S.; Fujisawa, I.; Shibatomi, K.; Iwasa, S. "Highly Stereoselective Spirocyclopropanation of Various Diazooxindoles with Olefins Catalyzed using Ru(II)-Complex" RSC Advances, 2018, 8, [39865-39869].DOI:10.1039/C8RA09212E (Open access)
  • Nakagawa, Y.; Imokawa, Y.; Fujisawa, I.; Nakayama, N.; Goto, H.; Chanthamath, S.; Shibatomi, K.; Iwasa, S. "Ligand Exchange Reaction on a Ru(II)-Pheox Complex as a Mechanistic Study of Catalytic Reactions" ACS Omega, 2018, 3, [11286–11289]. DOI:10.1021/acsomega.8b01510. (Open access)
  • Le, T. L. C.; Ozaki, S.; Chanthamath, S.; Shibatomi, K.; Iwasa, S. "Direct Cyclopropylphosphonation of Alkyl Group of Aniline Derivatives Catalyzed by Chiral Ru(II)-Pheox Complex "Organic Letters, 2018, 20, [4490–4494]. DOI: 10.1021/acs.orglett.8b01788.
  • Yamasaki, T.; Sato, N.; Hirakawa, Y.; Iwasa, S.; Narita, H.; Watanabe, T.; Miyake, S. "Development of Enzyme-Linked Immunosorbent Assay for Analysis of Total Aflatoxins Based on Monoclonal Antibody Reactive with Aflatoxins B1, B2, G1 and G2", Shokuhin eiseigaku zasshi. Journal of the Food Hygienic Society of Japan, 2018, 59, [200-205]. DOI: 10.3358/shokueishi.59.200.
  • Watanabe, E.; Yamasaki, T.; Hirakawa, Y.; Harada, A.; Iwasa, S.; Miyake, S. "Organic solvent-free immunoassay for neonicotinoid acetamiprid residues in agricultural products" Analytical Methods, 2018, 10, [3162-3169]. DOI: 10.1039/C8AY01061G.
  • Hirakawa, Y.; Yamasaki, T.; Harada, A.; Iwasa, S.; Narita, H.; Miyake, S. " Development of an Immunosensor Based on Surface Plasmon Resonance for Simultaneous Residue Analysis of the Three Pesticides, Boscalid, Clothianidin, and Nitenpyram, in Vegetables" Analytical Sciences, 2018, 34, [533-539]. DOI: 10.2116/analsci.17P487.
  • Kotozaki, M.; Chanthamath, S.; Fujii, T.; Shibatomi, K.; Iwasa, S. "Highly Enantioselective Synthesis of Trifluoromethyl Cyclopropanes by Using Ru(II)-Pheox Catalyst" Chemical Communications, 2018, 54, [5110-5113]. DOI: 10.1039/C8CC02286K.
  • Fakhruddin, A.; Abu-Elfotoh, A.-M.; Shibatomi, K.; Iwasa, S. "A New Synthetic Route to Acylnitroso Intermediates and Their Applications in HDA and Ene Reactions" Letters in Organic Chemistry,2018, 15, [195-205]. DOI: 10.2174/1570178614666170710101309.
  • Okawara, T.; Kawano, R.; Morita, H.; Finkelstein, A.; Toyofuku,R.; Matsumoto, K.; Takehara, K.; Nagamura, T.; Iwasa, S.; Kumar, S.,"Synthesis, Crystal Structure, and Photoluminescent Properties of 3,3′,4,4′-Tetraethyl-5,5′-divinyl-2,2′-bipyrrole Derivatives", Molecules, 2017, 22, [1816−1828].DOI: 10.3390/molecules22111816.
  • Kotozaki, M.; Chanthamath, S.; Fujisawa, I.; Shibatomi, K.; Iwasa, S. "Highly stereoselective cyclopropanation of various olefins with diazosulfones catalyzed by Ru(II)–Pheox complexes ", Chem. Commun., 2017, 53, [12193−12196].DOI: 10.1039/C7CC05951E.
  • Shibatomi, K.; Kitahara, K.; Sasaki, N.; Kawasaki, Y.; Fujisawa, I.; Iwasa, S. "Enantioselective decarboxylative chlorination of β-ketocarboxylic acids", Nature Commun., 2017, 8, 15600[1−7] . DOI: 10.1038/ncomms15600.
  • Nakagawa, Y.; Chanthamath, S.; Shibatomi, K.; Iwasa, S. Chem. Commun., 2017, 53, [3753−3756]. Contributor(s): Mark Lautens,Ivan Franzoni, Synfacts 2017, 13(06), 0623, "Ruthenium-Catalyzed Enantioselective Si–H Bond Insertion", DOI: 10.1055/s-0036-1590501.
  • Nakagawa, Y.; Chanthamath, S.; Shibatomi, K.; Iwasa, S. "Ru(II)-Pheox-Catalyzed Si–H Insertion Reaction: Construction of Enantioenriched Carbon and Silicon Centers" Chemical Communications,2017, 53, [3753–3756]. DOI: 10.1039/C7CC01070B.
  • Hamada, M, M.; Chanthamath, S.; Shibatomi, K.; Iwasa, S. "Inter- and Intramolecular Cyclopropanations of Diazo Weinreb Amides Catalyzed by Ruthenium(II)-Amm-Pheox" Advanced Synthesis & Catalysis, 2017, 359, [1742-1746]. DOI:10.1002/adsc.201601345.
  • Soda Chanthamath, Hamada S. A. Mandour, Tong Thi Minh Thu, Kazutaka Shibatomi and Seiji Iwasa "Highly Stereoselective Cyclopropanation of Diazo Weinreb amides Catalyzed by Chiral Ru(II)-Amm-Pheox Complexes" Chemical Communication, 2016, 52, [7814-7817]. DOI:10.1039/C6CC02498J.
  • Chanthamath, S.; Iwasa, S. "Enantioselective Cyclopropanation of a Wide Variety of Olefins Catalyzed by Ru(II)-Pheox Complexes" Account of Chemical Research, 2016, 46, [2080-2090]. DOI:10.1021/acs.accounts.6b00070.