- Total syntheses of coronatines by exo-selective Diels-Alder reaction and their biological activities on stomatal opening
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The natural phytotoxin coronatine, which is composed of two individual parts, coronafacic acid and coronamic acid, exhibits various promising biological activities similar to jasmonic acid. Interestingly, coronatine induces stomatal opening involving the swelling of guard cells in which jasmonic acid is not involved as an endogenous regulator. We established syntheses of four stereoisomers of coronatine employing the exo-selective Diels-Alder reaction as a key step. Remarkable differences in stomatal opening activity were observed between enantiomers of coronatine. This result strongly suggests that the stereo structure of coronatine is very important for its stomatal opening activity. In addition, SAR studies suggested that coronatine operates as a molecular mimic of jasmonyl-l-isoleucine in plant guard cells.
- Okada, Masahiro,Ito, Satoko,Matsubara, Akira,Iwakura, Izumi,Egoshi, Syusuke,Ueda, Minoru
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experimental part
p. 3065 - 3073
(2011/02/25)
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- Asymmetric total syntheses of (+)-coronafacic acid and (+)-coronatine, phytotoxins isolated from Pseudomonas Syringae pathovars
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Asymmetric total synthesis of (+)-coronafacic acid (2), was accomplished via intramolecular 1, 6-conjugate addition as the key step. The chiral ester (+)-7 was prepared via two approaches: starting from (R)-(+)-4-acetoxy-2- cyclopenten-1-one (12), and using catalytic asymmetric Michael reactions promoted by heterobimetallic BINOL complexes. Coupling between (+)-2 and the protected coronamic acid 8 and subsequent deprotection by hydrogenolysis provided (+)-coronatine (1). This is the first asymmetric total synthesis of(+)-1.
- Nara, Shinji,Toshima, Hiroaki,Ichihara, Akitami
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p. 9509 - 9524
(2007/10/03)
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- Asymmetric total syntheses of (+)-coronafacic acid and (+)-coronatine
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An asymmetric total synthesis of (+)-coronafacic acid, starting from (R)-(+)-4-acetoxy-2-cyclopen-1-one as a chiral source, was accomplished. Construction of the 1-hydrindanone framework was carried out by using intramolecular 1,6-conjugate addition as the key step. Coupling between (+)-coronafacic acid and protected coronamic acid, and subsequent deprotection provided (+)-coronatine. This is the first asymmetric total synthesis of (+)-coronatine.
- Toshima, Hiroaki,Nara, Shinji,Ichihara, Akitami
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p. 752 - 753
(2007/10/03)
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