Hajime Nagano

Publications (13)25.03 Total impact

• Article: Chemical constituents of Ligularia nelumbifolia and L. subspicata hybrid collected in Shangrila County, Yunnan Province of China.

  Ryo Hanai, Hiroka Yamada, Yurika Suzuki, Hajime Nagano, Takayuki Kawahara, Jiao-Jun Yu, Xun Gong, Chiaki Kuroda
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  ABSTRACT: Four Ligularia individuals possessing morphological characters of both L. nelumbifolia and L. subspicata were discovered in Shangrila County, Yunnan Province, China. DNA sequencing showed that the specimens were hybrids of the two species and their maternal parent was L. subspicata. The chemical composition of the root extract was examined for three of them as well as L. nelumbifolia and L. subspicata collected sympatrically. Nelumol was isolated from L. nelumbifolia, and furanoeremophilanes from L. subspicata. 1hile nelumol and furanoeremophilanes were detected in two of the hybrid samples, only furanoeremophilanes were detected in the others.
  Natural product communications 12/2012; 7(12):1565-8. · 1.24 Impact Factor
• Article: Diversity of furanoeremophilanes in major Ligularia species in the Hengduan Mountains.

  Chiaki Kuroda, Ryo Hanai, Hajime Nagano, Motoo Tori, Xun Gong
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  ABSTRACT: The chemical and genetic diversity of Ligularia species in the Hengduan Mountains area of China is reviewed. A hypothesis that the production of furanoeremophilanes is ecologically advantageous is proposed.
  Natural product communications 04/2012; 7(4):539-48. · 1.24 Impact Factor
• Article: Chemical and genetic study of Ligularia duciformis and related species in Sichuan and Yunnan Provinces of China.

  Hajime Nagano, Ryo Hanai, Hiroka Yamada, Mika Matsushima, Yui Miura, Takanori Hoya, Masaaki Ozawa, Miho Fujiwara, Hikari Kodama, Atsushi Torihata, Hiroyuki Onuki, Yoko Nezu, Satoru Kawai, Mizue Yamazaki, Hiroshi Hirota, Yoshinori Saito, Motoo Tori, Ayumi Ohsaki, Xun Gong, Chiaki Kuroda
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  ABSTRACT: The chemical constituents of the root extracts and the evolutionarily neutral DNA base sequences were studied for 28 samples of Ligularia duciformis, L. kongkalingensis, and L. nelumbifolia collected in Sichuan and Yunnan Provinces of China. The samples could be classified into four chemotypes (1-4). Sesquiterpenoids having eremophilane and oplopane skeletons were isolated from two (Chemotype 1) and three (Chemotype 2) samples, respectively. Two new oplopane derivatives were isolated and their structures were determined. In 18 samples, phenylpropenoids were the major components (Chemotype 3). In five samples, neither phenylpropenoids nor sesquiterpenoids were found (Chemotype 4). Despite this large chemical variety, no correlation was found between the chemotype and the morphological criteria of species identification. The analysis of the evolutionarily neutral DNA regions also indicated that the samples were not separated into distinct clades and that introgression was extensive.
  Chemistry & Biodiversity 04/2012; 9(4):789-805. · 1.80 Impact Factor
• Article: Chemical and Genetic Study of Ligularia anoleuca and L. veitchiana in Yunnan and Sichuan Provinces of China

  Hajime Nagano, Midori Kanda, Hiroka Yamada, Ryo Hanai, Xun Gong, Chiaki Kuroda
  Helvetica Chimica Acta 10/2010; 93(10):1945 - 1952. · 1.48 Impact Factor
• Article: Direct Racemic Mixture Synthesis of Fluorinated Amino Acids by Perfluoroalkyl Radical Addition to Dehydroamino Acids Terminated by Asymmetric Protonation

  Tomoko Yajima, Takayuki Tonoi, Hajime Nagano, Yuichi Tomita, Koichi Mikami
  Annalen der Chemie und Pharmacie 03/2010; 2010(13):2461 - 2464. · 3.10 Impact Factor
• Article: Two new furanoeremophilane sesquiterpenoids from Ligularia oligonema.

  Hajime Nagano, Mika Matsushima, Hiroka Yamada, Ryo Hanai, Xun Gong, Chiaki Kuroda
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  ABSTRACT: From the roots of Ligularia oligonema and an unidentified sample of Ligularia collected in Yunnan Province of China, two new sesquiterpenoids, 3beta-acetoxy-6beta-(2-methylbutyryloxy)furanoeremophilan-10beta-ol and 3beta-acetoxy-6beta-isobutyryloxyfuranoeremophilan-10beta-ol, were isolated. DNA sequencing showed that the unidentified sample was likely to be L. oligonema. In addition, the DNA data suggested that the chemical evolution among L. oligonema and related Ligularia species is rather complex.
  Natural product communications 01/2010; 5(1):1-4. · 1.24 Impact Factor
• Article: Chemical and Genetic Study of Ligularia cyathiceps in Yunnan Province of China

  Hajime Nagano, Atsushi Torihata, Mika Matsushima, Ryo Hanai, Yoshinori Saito, Makiko Baba, Yui Tanio, Yasuko Okamoto, Yuriko Takashima, Mayu Ichihara, Xun Gong, Chiaki Kuroda, Motoo Tori
  Helvetica Chimica Acta 10/2009; 92(10):2071 - 2081. · 1.48 Impact Factor
• Article: Fluorous Substituent‐Based Enantiomer and Diastereomer Separation: Orthogonal Use of HPLC Columns for the Synthesis of Nonproteinogenic Polyfluoro Amino Acids and Peptides

  Takayuki Tonoi, Aya Nishikawa, Tomoko Yajima, Hajime Nagano, Koichi Mikami
  Annalen der Chemie und Pharmacie 01/2008; 2008(8):1331 - 1335. · 3.10 Impact Factor
• Article: High diversity of Ligularia dictyoneura in chemical composition and DNA sequence.

  Hajime Nagano, Yukiko Iwazaki, Mika Matsushima, Masahiko Sato, Xun Gong, Yuemao Shen, Hiroshi Hirota, Chiaki Kuroda, Ryo Hanai
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  ABSTRACT: The chemical composition of root extracts of the title species collected at 20 different places in the Hengduan Mountains of China was examined. From these samples, a total of 17 eremophilane derivatives were isolated, three of which were new franoeremophilane derivatives: 3beta-acetoxy-6beta-(angeloyloxy)furanoeremophilan-10beta-ol, 1alpha-acetoxyfuranoeremophilan-15,6alpha-olide, and 6beta-[2-(hydroxymethyl)prop-2-enoyloxy]furanoeremophil-1(10)-ene. Based on the chemical composition, the samples could be classified into as many as seven types: one type containing non-furanoeremophilane derivatives and the other six containing furanoeremophilane derivatives with different oxidation levels. Results of DNA sequencing of the atpB-rbcL region and the internal transcribed spacers of the ribosomal RNA gene also indicated a high diversity in the species.
  Chemistry & Biodiversity 01/2008; 4(12):2874-88. · 1.80 Impact Factor
• Article: Photoinduced diastereoselective addition of perfluoroalkyl iodides to acrylic acid derivatives for the synthesis of fluorinated amino acids.

  Tomoko Yajima, Hajime Nagano
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  ABSTRACT: Photoinduced diastereoselective addition of perfluoroalkyl iodides in the presence of an aqueous solution of Na2S2O3 was an excellent method for iodoperfluoroalkylation of acrylic acid derivatives bearing a chiral auxiliary, with moderate to good stereoselectivities and with no detectable side products. The iodoperfluoroalkylation of N-acyloylcamphorsultam provided a convenient route for preparing chiral fluorine-containing amino acids.
  Organic Letters 07/2007; 9(13):2513-5. · 5.86 Impact Factor
• Article: Substituent effect on the diastereoselectivity in the chelation-controlled radical reactions of γ-(p-substituted-benzyloxy)-α-methylene esters with alkyl iodides

  Tomoko Yajima, Kyoko Okada, Hajime Nagano
  Tetrahedron. 60(27):5683-5693.
• Article: Stereoselectivity in the formation and radical reduction of cyclic bromoacetals, key intermediates for the synthesis of δ-hydroxy- and ε-hydroxy-α-methylcarboxylic acid esters

  Hajime Nagano, Ayako Mikami, Tomoko Yajima
  Tetrahedron Letters 44(36):6867-6870. · 2.68 Impact Factor
• Article: Radical-mediated hydroxyalkylation of α,β-unsaturated esters

  Tomoko Yajima, Chiaki Saito, Hajime Nagano
  Tetrahedron. 61(43):10203-10215.