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Two simple γ-lactonic cembranolides were isolated from the soft coral Sinularia mayi Lüttschw. and structurally elucidated on the basis of spectral and chemical evidence.

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We synthesized new vitamin K2 analogues with ω-terminal modifications of the side chain and evaluated their selective differentiation of neuronal progenitor cells into neurons in vitro. The result of the assay showed that the menaquinone-3 analogue modified with the m-methylphenyl group had the most potent activity, which was twice as great as the control. This finding indicated that it is possible to obtain much more potent compounds with modification of the structure of vitamin K2.

A new cembranolide diterpene, 7-epidenticulatolide, was isolated from a soft coral, Lobophytum denticulatum. The structute was deduced spectroscopically and determined by X-ray crystallography.

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The condensation of 7-benzoyloxy-4′-hydroxyisoflavone with 2-methyl-3-buten-2-ol gave 7-benzoyloxy-4′-hydroxy-3′-(3-methyl-2-butenyl)isoflavone. The hydrolysis of the alkylated isoflavone with dilute alkali afforded neobavaisoflavone [7,4′-dihydroxy-3′-(3-methyl-2-butenyl)isoflavone], which was then converted into isoneobavaisoflavone on heating with formic acid. 7-Benzyloxy-4′-hydroxyisoflavone was condensed with 2-methyl-3-buten-2-ol to give a chroman derivative, which was then converted into isoneobavaisoflavone by hydrolysis. 3′-(3-Methyl-2-butenyl)-5,7,4′-trihydroxyisoflavone was also synthesized from 7-benzoyloxy-5,4′-dihydroxyisoflavone in a similar manner.

The mass spectral fragmentation behaviour of some Iabda-7,14-dien-l3(R)-01 monoglycosides has been studied. Mass spectra of 0-isopropylidine derivatives of the glycosides have been determined to distinguish the isomeric sugar moieties containing rhamnopyranose, fucopyranose and 6-deoxyidopyranose, respectively. The main fragment ions of the sugar moieties were investigated with the aid of deuterium labelling and high resolution mass measurement. INTRODUCIlONAlthough there are many reports concerning mass spectrometric studies on derivatives of glycosides such as methyl ether, acetate and trimethylsilyl ether, their spectra showed no significant differences regarding the sugar parts. While the mass spectra of 0-isopropylidene derivatives of pentoses and hexoses have been reported,' their application to natural glycosides for the determination of the sugar moiety has so far only been reported for a few examples.* Several labdane type diterpene monoglycosides have been isolated from a methanolic extract of Aster spathulifulius Maxim. and their structures have been determined on the basis of chemical and spectral data.3 Compounds 1-3 were the monoglycosides of labda-7,14-dien-l3(R)-01, each containing a-L-rhamnopyranose, P-D-fucopyranose and a-~-6-deoxyidopyranose which are all 6-deoxyhexoses as the sugar parts. This paper describes the electron impact (EI) mass spectra of monoglycosides of labda-7,14-dien-13(R)-01 (1-3) and 0-isopropylidene derivatives of the glycoside (1 and 2). ing voltage of 3.2 kV. High resolution data were recorded on an Hitachi RMU-7L double focusing mass spectrometer using a direct insertion probe, an ionizing voltage of 70 eV and an accelerating voltage of 3.2 kV. Glycosides (1-3).The natural glycosides were isolated by a combination of column and preparative thin-layer chromatography (TLC). 2,3-O-Isopropylidene derivative of labda-7,14-dien-I3(R)-ol-a-L-rhamnopyranoside (la).A mixture of 50 mg of compound 1 , l O mg of p -toluenesulfonic acid and anhydrous acetone (10 ml) was stirred for 5 h at room temperature. The reaction mixture was neutralized with 10% aq. N b O H and filtered and concentrated in z)ucuu, then applied to a preparative TLC plate to obtain the pure acetonide derivative l a as an oil. H nuclear magnetic resonance (NMR) (C2H302H): 6 1.33, 150 (each 3H, s, acetonide methyls).