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Several tricyclo[5.3.1.01,5]undec-9-ene-8,11-diones have been synthesized in stereospecific manner, by using electrochemical oxidation of the corresponding phenols with trans or cis para-halo substituted styryl group. Two of the products were subjected to base-catalyzed fragmentation reaction to afford two different types of bicyclic compounds selectively, one of which has been readily converted into a triquinane-type compound.

Two new glucosides, cropapine and cronupapine, have been isolated from the plant Cronura papirio and their structures have also been elucidated on the basis of their spectral data coupled with some...

9-Methoxy-6β-(3′,4′-dimethoxyphenyl)-2β,5α-dimethyltricyclo[5.4.0.01,5]undec-9-en-8,11-dione has been synthesized by using electrochemical oxidation of the corresponding phenol and then readily converted into a triquinane-type compound in 8 steps.

Four new high potent antifeeding substances, citreohybriddiones A and B and isocitreohybridones A and B, have been isolated from the mycelium of a hybrid strain KO 0031 derived from Penicillium citreo-viride B. IFO 6200 and 4692. Their stereostructures have also been elucidated on the basis of their spectral data and some chemical evidence.

In connection with sulfur-containing alkaloids, prianosins, a spiro derivative has been synthesized by phenolic oxidation of a phenol precursor with thallium(III) oxidation or electrochemical oxida...

6-Hydroxy-8-methoxy-3S,5-dimethylisochroman and 6-hydroxy-8-methoxy-3S,5-dimethyl-3,4-dihydroisocoumarin have been isolated from the mycelium of a hybrid strain ME 0004 derived from Penicillium citreo-viride B. IFO 6200 and 4692. The latter has also been produced by the hybrid strain ME 0005 in addition to 11-β-hydroxy-12-oxocurvularin.

Racemic 9-hydroxy-10-oxo-12(Z),15(Z)-octadecadienoic acid [(±)-KODA] was synthesized via a coupling reaction between a diyne and an epoxide derived from methyl oleate as a key step. An optically active 9R-KODA was also synthesized by enantioselective lipase-catalyzed esterification of an allyl alcohol. Both synthetic (±)-KODA and 9R-KODA showed remarkable flower-inducing activity in Pharbitis nil.

Six new metabolites, citreopyrones A-C and D-F, have been isolated from the mycelium of a hybrid strain KO 0092 derived from P. citreo-viride B. IFO 4692 and 6200, and KO 0141 derived from P. citreo-viride B. IFO 4692 and P. pedemontanum IFO 9583. Their structures have also been elucidated on the basis of their spectral data and some chemical evidence. Citreopyrones A, B, and C inhibited the growth of hypocotyls of lettuce seedlings.

Biologically active griseulin isolated from Streptomyces sp. was synthesized, however the spectral data of the synthetic sample did not agree with the reported one. Synthesis of the related sample and detailed reexamination of the spectroscopic properties resulted in the structural revision of griseulin, which should be identical with luteoreticulin.

A practical synthesis of the cyclopentane derivative shared by the diterpenes isolated from the plant Euphorbia helioscopia L. has successfully been accomplished starting from the optically active cyclopenten-diol derivative.

Total syntheses of batzelline C and isobatzelline C, two chlorine-containing alkaloids have been successfully accomplished employing the tricyclic indole derivative as a key intermediate.

Anodic oxidation of 4-hydroxycinnamic acids was carried out at a controlled potential vs. SCE (+900 or 840 mV), using an undivided cell, to afford the corresponding asatone or isoasatone-type compound as well as pinoresinol-type dilactones. In these oxidation reactions, relative ratio of the two dimerization products remarkably depends on the starting acids concentration.

In an effort to search for stimulants concerning with circadian rhythm in several nyctinastic plants, potassium chelidonate was isolated as a bioactive substance from the plant Cassia mimosoides L. and C. occidentalis L. This potassium salt has been proved to be quite effective for leaf-closing of the plants Mimosa pudica, Cassia mimosoides L. and others.

Oxidation of 4-allylphenols in MeOH has been carried out using thallium (III) nitrate to give two different types of reaction product. In the cases of 4-allylphenols with an electron-donating group (MeO), methoxylation takes place on the aromatic ring resulting in the formation of asatone-type compound as well as of 2,5-cyclohexadien-1-one. In the case of 4-allyl-2-methoxy-6-nitrophenol, however, the allyl group was attacked by the reagent to give three phenols.

Epoxygermacrene-D was treated with basic alumina to afford a new type of sesquiterpene, whose stereostructure was determined on the basis of its spectral data coupled with an X-ray crystallographic analysis of the corresponding ketone produced on CrO3 oxidation.

Some phenols with an olefinic double bond at the side chain have been subjected to anodic oxidation under various conditions to afford tricyclo[5.3.1.01,5]undec-9-en-8,11-diones and two different spiro compounds, precursors of bioactive natural products.

Some esters with two C6–C3 units have been oxidized with thallium (III) trifluoroacetate to afford the corresponding lactones of medium-sized rings, one of which is an 11-membered ring lactone, an 8,8′-secosteganacin-type compound.

On treatment with MeONa–MeOH (under reflux, 7–9 h), shyobunone and related compounds were converted into a mixture of six possible isomers (1, 2, 3, 4, 5, and 6), including the starting material, in the following ratio: 1/2/3/4/5/6 = 3 : 6 : 3 : 1 : 7 : 13. In the cases of the corresponding dihydro compounds, six isomers were also obtained in the following ratio remarkably different from that of shyobunone [7/8/9/10/11/12 = 23 : 7 : 14 : 15 : 21 : 19]. The stereostructures and conformations of these compounds are discussed on the basis of their ORD data.

Epiisocitreoviridinol, biogenetically relevant to citreoviridinol, has been isolated as a new metabolite of Penicillium citreo-viride B. (IFO 6049). Its stereostructure including the absolute configuration has been determined unambiguously by its total synthesis in optically active form.

Both citreoviridinol and neocitreoviridinol, metabolites of Penicillium citreo-viride B., have been synthesized from the known synthetic intermediate of citreoviridin, in regio- and stereoselective manner.

Two new metabolites (citreovirenone and citreovirone) have been isolated from the mycelium of Penicillium citreo-viride B. (IFO 4692) and their structures have also been elucidated on the basis of their spectral data coupled with some chemical evidence.

The absolute configuration of epi- and isoshyobunone was established as 2 and 3, respectively, on the basis of their chemical and spectral data together with base-catalyzed isomerization of shyobunone (1) affording natural isoshyobunone and the enantiomer of natural epishyobunone. In addition, conformations of the base-catalyzed isomerization products (3, 6, 8, 9, and 11) are also discussed.

Deoxysilydianin methyl ether has been readily synthesized by means of anodic oxidation of the corresponding phenol as a key step, indicating a general method for synthesis of 9-oxaisotwist-8-en-2-ones in high yields.

In addition to obtusilactone (I), three new lactones (II, III and IV) have been isolated from the plant Lindera obtusiloba Blume, and their structures also been established in connection with I.

Aureothin, isoaureothin, and related compounds have been synthesized in short steps starting from 3,5-dimethyl-6-formyl-4-methoxy-2-pyrone. In addition, the geometry of the conjugated double bonds in isoaureothin and its isomers has been unambiguously determined on the basis of NOE experiments.

Two new pyrones, citreoviridinol and secocitreoviridin, have been isolated from the yellow rice, and their structures also been elucidated on the basis of their spectral data.

Three new diterpenes, helioscopinolides A, B and C, have been isolated from the plant Euphorbia helioscopia L., and their stereostructures also been elucidated on the basis of their spectral and chemical data coupled with an X-ray crystallographic analysis of helioscopinolide A.

Anodic oxidation of 4-allyl-2-methoxyphenol was carried out under various conditions, using an undivided cell, to afford two dienones (3 and 4) and two dimeric compounds (5 and 6). The dienone (4) was readily converted into demethoxyasatone (6), which was further subjected to photochemical reaction giving demethoxyisoasatone (7) in a good yield.

Five new alkaloids have been isolated from the plant Daphniphyllum gracile Gage, and their structures also been elucidated on the basis of their spectral and chemical evidences. Particularly, daphnigraciline methiodide (VI) was directly converted into yuzurine methiodide (VII). Furthermore, application of 13C NMR spectra plays an important role in the structural elucidation.

Triacetic lactone, 4-hydroxycoumarins, and kojic acid derivative were subjected to anodic oxidation in MeOH containing LiClO4 or NaCN to afford the corresponding methoxy or cyano compounds. In a basic media, however, dipyrone and dicoumarol were produced from triacetic lactone and 4-hydroxycoumarin, respectively. The formation process of 3-methoxytriacetic lactone as well as of 3-cyanotriacetic lactone is also presented.

Isolation of two new selinane-type sesquiterpenes, named acolamone (II) and isoacolamone (III), is described and their structures have also been elucidated in connection with the base catalyzed cyclization of an epoxygermacrone (IV), which has been derived from preisocalamendiol, leading to the formation of a selinane-type α,β-unsaturated ketone (V).

Two novel neolignans, heterotropanone and isoheterotropanone, have been synthesized by retro-Diels–Alder reaction of asatone in l-allyl-3,4,5-trimethoxybenzene. These two neolignans have also been obtained on thermal reaction of asatone followed by methylation.

C19-Obtusilactone dimer, a cytotoxic substance, has been isolated from Lindera obtusiloba Blume, and its structure also been elucidated on the basis of its spectral data coupled with chemical evidence.

Two new neolignans, isoasatone A (3) and isoasatone B (4) have been isolated from the plant Heterotropa takaoi M., and their structures also been elucidated by comparing their spectral data with those of asatone (1).

Bastadin-6, a 28-membered ring lactam, was synthesized from the known bis-p-methoxybenzyl bastadin-2 in 6 steps.