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Koji Hasegawa

Bio: Koji Hasegawa is an academic researcher from Kagoshima University. The author has contributed to research in topics: Phototropism & Coleoptile. The author has an hindex of 16, co-authored 39 publications receiving 726 citations. Previous affiliations of Koji Hasegawa include Miyagi University of Education & University of Tsukuba.
Topics: Phototropism, Coleoptile, Hypocotyl, Auxin, Dormancy

Papers
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Journal ArticleDOI
TL;DR: Two new oxylipins, arabidopsides C and D, were isolated from the aerial parts of Arabidopsis thaliana, and the structures of 1 and 2 were elucidated using spectroscopic data, primarily NMR and MS, and chemical means.
Abstract: Two new oxylipins, arabidopsides C (1) and D (2), were isolated from the aerial parts of Arabidopsis thaliana, and the structures of 1 and 2 were elucidated using spectroscopic data, primarily NMR and MS, and chemical means. Arabidopsides C (1) and D (2) are rare digalactosyl diacylglycerides containing 12-oxophytodienoic acid and/or dinor-oxophytodienoic acid. Arabidopside D (2) and arabidopsides A (3) and B (4), which were also isolated from this plant, exhibited inhibitory effects on the growth of the root of cress (Lepidium sativum) seedlings at 5 x 10(-5) mol/L.

88 citations

Journal ArticleDOI
TL;DR: In this paper, two new oxylipins, arabidopsides A (1) and B (2), were isolated from the aerial parts of Arabidopsis thaliana, and their structures and absolute stereochemistries were elucidated by spectroscopic data and chemical means.

81 citations

Journal ArticleDOI
Tohru Hashimoto, Koji Hasegawa, Hisao Yamaguchi1, Masahiko Saito1, Ishimoto Sachio1 
TL;DR: Batatasin, which occurs in dormant bulbils of yams and induces dormancy in this organ has been shown by spectrometric analysis and synthesis to be 3,3′-dihydroxy-5-methoxy-bibenzyl.

52 citations

Journal ArticleDOI
01 Dec 1972-Planta
TL;DR: Three growth inhibitors, for which the names batatasins I, II and III are proposed, occur in dormant yam bulbils and suppresses the sprouting of bulbils, and the inhibition is reversible by low-temperature stratification.
Abstract: Three growth inhibitors, for which the names batatasins I, II and III are proposed, occur in dormant yam bulbils. Application of these inhibitors suppresses the sprouting of bulbils, and the inhibition is reversible by low-temperature stratification. Batatasins I and III were isolated as crystals and partially characterized as phenotic compounds not identical with known inhibions.

45 citations

Journal ArticleDOI
TL;DR: Against the wholly indirect evidence of a lateral gradient of auxin as an explanation of phototropic curvature according to the Cholodny-Went theory, direct measurement of free.
Abstract: Against the wholly indirect evidence of a lateral gradient of auxin as an explanation of phototropic curvature according to the Cholodny-Went theory, direct measurement of free. extractable or diffusable indoleacetic acid from phototropically curving hypocotyls and coleoptiles invariably shows an even distribution of auxin. On the contrary, growth inhibitors extracted or diffused from these organs turn out to be accumulated at the irradiated side, as proposed already by A. H. Blaauw (Z. Bot. 7: 465. 1915). the classical experiment by F. W. Went (Rec. Trav. Bot. Neerl. 25:1, 1928) has to be interpreted as evidence for a lateral gradient of substance(s) inhibiting auxin activity Phototropic curvature is thus a matter of differential auxin sensitivity across the unilaterally irradiated organ.

42 citations


Cited by
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Journal ArticleDOI
TL;DR: This review summarizes biosynthesis and signal transduction of jasmonates with emphasis on new findings in relation to enzymes, their crystal structure, new compounds detected in the oxylipin andJasmonate families, and newly found functions.

1,687 citations

Journal ArticleDOI
TL;DR: This review provides an overview on the use of anodic electrochemical methods for expediting the development of carbon-hydrogen functionalization and carbon-nitrogen bond formation strategies and aims to provide inspiration for future synthetic applications in the field of electrosynthesis.
Abstract: Conventional methods for carrying out carbon–hydrogen functionalization and carbon–nitrogen bond formation are typically conducted at elevated temperatures, and rely on expensive catalysts as well as the use of stoichiometric, and perhaps toxic, oxidants. In this regard, electrochemical synthesis has recently been recognized as a sustainable and scalable strategy for the construction of challenging carbon–carbon and carbon–heteroatom bonds. Here, electrosynthesis has proven to be an environmentally benign, highly effective and versatile platform for achieving a wide range of nonclassical bond disconnections via generation of radical intermediates under mild reaction conditions. This review provides an overview on the use of anodic electrochemical methods for expediting the development of carbon–hydrogen functionalization and carbon–nitrogen bond formation strategies. Emphasis is placed on methodology development and mechanistic insight and aims to provide inspiration for future synthetic applications in the field of electrosynthesis.

626 citations

Journal ArticleDOI
TL;DR: The scope of this novel method for the preparation of polycyclic arenes is illustrated by thetotal synthesis of a series of polyoxygenated phenanthrenes that are close relatives of the anticancer agent combretastatin A-4, as well as by the total synthesis of the aporphine alkaloid O-methyl-dehydroisopiline and its naturally occurring symmetrical dimer.
Abstract: Readily available biphenyl derivatives containing an alkyne unit at one of their ortho-positions are converted into substituted phenanthrenes on exposure to catalytic amounts of either PtCl2, AuCl, AuCl3, GaCl3 or InCl3 in toluene. This 6-endo-dig cyclization likely proceeds through initial pi-complexation of the alkyne unit followed by interception of the resulting eta2-metal species by the adjacent arene ring. The reaction is inherently modular, allowing for substantial structural variations and for the incorporation of substituents at any site of the phenanthrene product. Moreover, it is readily extended to the heterocyclic series as exemplified by the preparation of benzoindoles, benzocarbazoles, naphthothiophenes, as well as bridgehead nitrogen heterocycles such as pyrrolo[1,2-a]quinolines. Depending on the chosen catalyst, biaryls bearing halo-alkyne units can either be converted into the corresponding 10-halo-phenanthrenes or into the isomeric 9-halo-phenanthrenes; in the latter case, the concomitant 1,2-halide shift is best explained by assuming a metal vinylidene species as the reactive intermediate. The scope of this novel method for the preparation of polycyclic arenes is illustrated by the total synthesis of a series of polyoxygenated phenanthrenes that are close relatives of the anticancer agent combretastatin A-4, as well as by the total synthesis of the aporphine alkaloid O-methyl-dehydroisopiline and its naturally occurring symmetrical dimer.

521 citations

Journal ArticleDOI
TL;DR: The interplay of different subcellular compartments during oxylipin biosynthesis suggests complex mechanisms of regulation that are not well understood, and a multitude of enzymes responsible for their biosynthesis are included.

369 citations