Tadashi Masamune

Laurencin, a constituent of Laurencia glandulifera Kutzing

Abstract Laurencin, a new bromo compound isolated from Laurencia glandulifera Kutzing, is represented by formula I on the basis of spectral and chemical evidence.

Laurinterol, debromolaurinterol and isolaurinterol, constituents of Laurencia intermedia Yamada

Abstract A new type of sesquiterpenoid containing bromine and its debromo analog, laurinterol (I) and debromolaurinterol (II), as well as an isomeric bromo compound, isolaurinterol (III), have been isolated from Laurencia intermedia Yamada (Rhodomelaceae), and their structures determined.

Laurepinnacin and isolaurepinnacin, new acetylenic cyclic ethers from the marine red alga Laurencia pinnata Yamada

The Structure elucidation of the title compounds, two new insecticidal components of the marine red alga Laurencia pinnata Yamada, is described.

Laurene, a sesquiterpene hydrocarbon from Laurencia species.

Abstract Laurene, a new sesquiterpene hydrocarbon from Laurencia glandulifera Kutzing and L. nipponica Yamada, is shown to possess structure I. Isolaurene (IV) and epilaurene (XX) have been synthesized.

Syntheses and NMR spectra of 22,27-imino-17,23-oxidojervane derivatives☆

Abstract A number of 22,27-imino-17,23-oxidojervane derivatives have been synthesized. The chemical shift values for all the Me groups of 65 derivatives of jervane are presented, and the effects of many different substituents on these chemical shifts are analysed. The additivity principle is shown to hold satisfactorily for the 19-Me protons of these C-nor-D-homosteroid alkaloids.

Synthesis of (±)-prepinnaterpene, a bromoditerpene from the red alga Laurencia Pinnata Yamada

Abstract A total synthesis of (±)-prepinnaterpene, a brominated diterpene with a unique skeleton, and (±)-oppositol, a related sesquiterpene, is described.

Antifungal compounds from Dioscorea batatas inoculated with Pseudomonas cichorii

Abstract An induced and six preformed antifungal compounds were isolated from Chinese yam ( Dioscorea batatas ) inoculated with the bacterium Pseudomonas cichorii . The induced compound, a phytoalexin, was identified as dihydropinosylvin. The preformed compounds were characterized as oxygenated bibenzyls and phenanthrenes.

Structures of moracins E, F, G, and H, new phytoalexins from diseased mulberry

Abstract The structures and antifungal activity of four new mulberry phytoalexins, designated as moracins E, F, G, and H, are described.

Confirmation of the structures of kuwanons G and H (albanins F and G) by partial synthesis

Abstract Conclusive evidence is presented supporting structures 1 and 2 for two natural Diels-Alder adducts isolated from mulberry and designated as kuwanon G (albanin F, moracenin B) and Kuwanon H (albanin G, Moracenin A).

Ecdysone-like metabolites, 14α-hydroxypinnasterols, from the red alga Laurencia pinnata

Abstract Four steroids with moulting hormone activity were isolated from Laurencia pinnata . These steroids are related structurally to β-ecdysone.