1. Rice blast disease, caused by infection of rice blast fungus Magnaporthe grisea, has been the most serious pest for rice. To date several salicylaldehyde type pathogenic compounds have been isolated from the fungus such as pyriculol and pyriculariol.4 Recently, Kim et al. isolated an additional compound with a novel carbon framework from the culture filtrate of the fungus, M. grisea (Hebert) Barr (imperfect stage of Pyricularia oryzae Cavara), and named it pyricuol. Racemic and chiral synthesis of pyricuol was achieved to confirm its absolute configuration.
2. Plausible biosynthetic precursor of monilidiol, a phytotoxin isolated from a cherry brown rot fungus Monilinia fructicola, was synthesized.


243. "Synthesis of (12R,13S)-Pyriculariol and (12R,13S)-Dihydropyriculariol Revealed that the Rice Blast Fungus, Pyricularia oryzae, Produces these Phytotoxins as Racemates"
　　Yuta Nagashima, Ayaka Sasaki, Ryoya Hiraoka, Yuko Onoda, Koji Tanaka, Zi-Yi Wang, Atsuki Kuwana, Yuji Suzuki, Minoru Izumi, Shigefumi Kuwahara, Manabu Nukina, and Hiromasa Kiyota, Biosci. Biotechnol. Biochem., 85(1), 134-142 (2021).

242. "Controlling the Production of Phytotoxin Pyriculol in Pyricularia oryzae by Aldehyde Reductase"
　　Yuuki Furuyama, Takayuki Motoyama, Toshihiko Nogawa, Toshiaki Hayashi, Hiroshi Hirota, Hiromasa Kiyota, Takashi Kamakura, and Hiroyuki Osada, Biosci. Biotechnol. Biochem., 85(1), 126-133 (2021).

230. "Synthetic Studies of Salicylaldehyde-type Phytotoxins Isolated from Rice Blast Fungus"REVIEW
　　Hiromasa Kiyota, Journal of Synthetic Organic Chemistry, Japan, 77(2), 173-180 (2019).

197. "5-(2,2-Dimethyl-4H-1,3-benzodioxin)methanol: the Synthetic Precursor to o-Formyl-m-Hydroxycinnamic Acid, the Most Oxidized Salicylaldehyde-Yype Phytotoxin Isolated from Rice Blast Fungus, Magnaporthe grisea"
　　Akihito Saito, Konosuke Hiramatsu, Hai-Qun Cao, Yuta Nagashima, Koji Tanaka, Ayaka Sasaki, Teiko Yamada, Shigefumi Kuwahara, Manabu Nukina, Hiromasa Kiyota, Heterocycl. Commun. 20(3), 185-188.

165. "Biotransformation of Plausible Biosynthetic Intermediates of Salicylaldehyde-type Phytotoxins of Rice Blast Fungus, Magnaporthe grisea"
　　Koji Tanaka, Ayaka Sasaki, Hai-Qun Cao, Teiko Yamada, Masahiro Igarashi, Isao Komine, Hirokazu Nakahigashi, Naoko Minami, Shigefumi Kuwahara, Manabu Nukina, Hiromasa Kiyota, Eur. J. Org. Chem., 6276-6280 (2011).

141. "Synthesis and Plant Growth Inhibitory Activity of Both Enantiomers of Pyricuol, a Phytotoxin Isolated from Rice Blast Disease Fungus Magnaporthe grisea"
　　Koji Tanaka, Yoko Nakamura, Rumi Ueda, Ayaka Sasaki, Yuji Suzuki, Shigefumi Kuwahara, Hiromasa Kiyota, Tetrahedron, 65 (31), 6115-6122 (2009).

140. "First Synthesis and Absolute Configuration of (-)-Pyriculariol, a Phytotoxin Isolated from Rice Blast Fungus, Magnaporthe grisea. Use of Microwave Irradiation to Cotrol Stille Coupling Reaction Products"
　　Ayaka Sasaki, Koji Tanaka, Yuuki Sato, Shigefumi Kuwahara, Hiromasa Kiyota, Tetrahedron Lett., 50 (31), 4637-4638 (2009).

76. "Synthesis to Determine the Absolute Configuration of (-)-Pyricuol, a Phytotoxin Isolated from Rice Blast Disease Fungus Magnaporthe grisea"
　　Yoko Nakamura, Hiromasa Kiyota, Rumi Ueda, Shigefumi Kuwahara, Tetrahedron Lett., 46, 7107-7109 (2005).

54. "First Synthesis of (+-)-Pyricuol, a Plant Pathogen Isolated from Rice Blast Disease Fungus Magnaporthe grisea"
　　Hiromasa Kiyota, Rumi Ueda, Takayuki Oritani, Shigefumi Kuwahara, Synlett, 219-220 (2003).

Tabtoxinine-beta-lactam (T-beta-L), tobacco wildfire disease toxin

Wildfire disease has been the most serious pest for tobacco since the early-twentieth century. Tabtoxin and its serine-homolog, are inactive themselves. However, when they are hydrolyzed by host plant aminopeptidases, the resulting true phytotoxin tabtoxinine-beta-lactam (T-beta-L, 1) causes chlorosis by irreversible inactivation of the host plant glutamine synthetase (GS). Although tabtoxin is available by fermentation, hydrolysis of the amide bond is complicated by isomerization to stable isotabtoxins or tabtoxinine-delta-lactam (T-delta-L) (t1/2 = 24 h at pH 7.0 and 15 min at pH 4.5). The mechanism of action of T-beta-L are postulated to be similar to that of GS inhibitor, L-methionine-S-sulfoximine, whose in vivo phosphorylated product mimicks the true GS intermediate L-glutamic acid gamma-phosphate. N- or O-phosphorylated TβL would mimick it similarly. Total synthesis of tabtoxinine-beta-lactam 1 was achieved from L-serine using a zinc-mediated coupling reaction, Sharpless asymmetric dihydroxylation and lactamization of N-OBn amide as the key steps.

93. "Synthetic Studies on Heterocyclic Antibiotics Containing Nitrogen Atoms"REVIEW
　　H. Kiyota, in "Topic in Heterocyclic Chemistry 06: Bioactive Heterocyles 1", ed. S. Eguchi, Chapter 6, Springer 2006, pp 181-214.

111. "Synthesis of (-)-Tabtoxinine-beta-lactam, the Phytotoxin of Tobacco Wildfire Disease
　　H. Kiyota, Takafumi Takai, Yasuharu Shimasaki, Masatoshi Saitoh, Osamu Nakayama, Tomoko Takada, S. Kuwahara, Synthesis, 2471-2480 (2007).

67. "Facile Synthesis of tabtoxinine-beta-lactam and its (3'R)-isomer"
　　Hiromasa Kiyota, Takafumi Takai, Masatoshi, Saitoh, Osamu Nakayama, Shigefumi Kuwahara, Tetrahedron Lett., 45, 8191-8184 (2004).

Synthetic studies of eremophilane-type phytotoxins

Four eremophilane sesquiterpene phytotoxins were synthesized using enantioselective yeast reduction of keto-ester[scheme]

1. "Synthesis of Oxygenated Eremophilanes, Gigantenone, Phomenone and Phaseolinone, Phytotoxins from Pathogenic Fungi"
　　T. Kitahara, H. Kiyota, H. Kurata, K. Mori, Tetrahedron, 47(9), 1649-1654 (1991).

21. "Synthesis of Dendryphiellin C, a Trinor-sesquiterpene from a Marine Source"
　　H. Akao, H. Kiyota, T. Nakajima, T. Kitahara, Tetrahedron, 55(25), 7757-7770 (1999).