Takeyoshi Sugiyama

Phenolic ferrier reaction and its application to the natural product synthesis

Abstract Aryl O -Δ 2 -glycosides were synthesized by Ferrier reaction. p -Methoxyphenyl group was oxidatively removed with Ag(DPAH) 2 .

Three new taxane diterpenoids from the seeds of Taxus yunnanensis Cheng et L. K. Fu and T. cuspidata Sieb et Zucc

Abstract Chemical examination of the seeds of the Chinese yew, Taxus yunnanensis Cheng et L. K. Fu and Japanese yew, T. cuspidata Sieb et Zucc resulted in the isolation of three new and rare rearranged abeo taxane type of diterpenoids in addition to several known compounds. The structures of the new taxoids have been established as 9α, 13 α -diacetoxy-11(15→1) abeo taxa-4(20), 11-diene-5α, 10β, 15-triol ( 1 ), 9α, 9 α , 13 α -diacetoxy-10β-benzoyloxy-5α-(3′-dimethyl-amino-3′-phenyl)-propionyloxy-11(15→1) abeo taxa-4(20), 11-diene-15-ol ( 2 ), and 2 α ,7 β ,13 α -triacetoxy-10β-hydroxy-5α-(3′-dimethylamino-3′-phenyl)-propionyloxy-2(3→20)- abeo -taxa-9-one ( 3 ) by a study of their spectral data.

Two bicyclic taxane diterpenoids from the needles of taxus mairei

Abstract Two new bicyclic taxane diterpenoids were isolated from the needles of the Chinese yew, Taxus mairei . Their structures were established as 13-deacetylcanadensene and 7-deacetylcanadensene with the aid of spectroscopic techniques, including 1D and 2D NMR spectroscopies.

Isolation and Identification of New Antifungal Macrophorins E, F and G as Malonyl Meroterpenes from Botryosphaeria berengeriana

Macrophorins E, F and G were newly isolated from Botryosphaeria berengeriana, each showing potent antifungal activity similar to that of macrophorin A against phytopathogenic fungi B. berengeriana and Gibberella fujikuroi. Macrophorins E and G were identified as novel malonylated derivatives of macrophorin A, and F as a macrophorin E congener with a hydroxy-cyclohexenedione moiety instead of its epoxy-cyclohexenone one.

Two novel pseudoalkaloid taxanes from the Chinese yew, Taxus chinensis var. mairei

Abstract Two pseudoalkaloid taxane diterpenoids were isolated from seeds of the Chinese yew tree Taxus chinensis var. mairei. Their structures were established as 2α,9α,10β,13α-tetraacetoxy-5α(3′-methylamino-3′-phenyl)-propionyloxy-taxa-4(20),11-diene and 7β,9α,10β,13α-tetraacetoxy-5α(3′-methylamino-3′-phenyl)-propionyloxy-taxa-4(20),11-diene, with the aid of NMR spectral and FAB-MS data analysis.

A Newly Rearranged 2(3→20)Abeotaxane Diterpene from the Bark of Chinese Yew, Taxus mairei

A newly rearranged 2(3→20)abeotaxane diterpenoid with a unique 6/10/6 skeleton was isolated from the bark of the Chinese yew, Taxus mairei. The structure was established as being 7β,13α-diacetoxy-2α,5α,10β-trihydroxy-9-keto-2(3→20)abeotaxane on the basis of 1-D and 2-D NMR data. The relative stereochemistry was defined from the results of a NOESY experiment. This is the first reported isolation of a rearranged 2(3→20)abeotaxane from Taxus mairei.

A convergent synthesis of optically active aspyrone.

Abstract Aspyrone ( 1 ) was elabolated in an optically pure form by the key reaction involving a nucleophilic addition of δ-lactone enolate to 2-tosyloxyaldehyde and a subsequent in situ formation of epoxide.

Three rearranged 2(3→20) abeotaxanes from the bark of Taxus mairei

Abstract Three new rearranged 2(3→20) abeo taxane diterpenoids were isolated from the bark of the Chinese yew, Taxus mairei . Their structures were established as 2α,5α,7β,13α-tetraacetoxy-10β-hydroxyl-2(3→20) abeo taxan-9-one; 7β,13α-diacetoxyl-2α,5α,10β-trihydroxyl-2(3→20) abeo taxan-9-one and 2α,7β-diacetoxy-5α,10β,13α-trihydroxyl-2(3→20) abeo taxane-9-one on the basis of 1D and 2D NMR data. This is the first example of rearranged 2(3→20) abeo taxanes were isolated from Taxus mairei .

Bicyclic Taxane With A Verticillene Skeleton From the Needles of Chinese Yew, Taxus Mairei

Abstract Two bicyclic taxanes were isolated from the needles of the Taxus mairei. One was a new compound, the structure of which was established as (3E, 7 E)-2α,5α,10β,13α,20-pentaacetox-3,8-sectoaxa-3, 7, 11-trien-9-one (1) on the basis of 1D and 2D NMR data. This is the first example of bicyclic taxane with a verticillene skeleton as a natural product. Another new natural product was identified as 5-acetyltaxachitriene A (2).

Taxane Diterpenoids From the Seeds of Chinese Yew, Taxus Mairei

Abstract Nine taxane diterpenoids were isolated from the seeds of Taxus mairei. One of them was a novel compound with the structure (1) which was established as 9α, 10β, 13α-triacetoxy-5α(3′ -methylamino-3′ -phenyl)-propionyloxy-taxa-4(20), 11 -diene on the basis of 1H NMR data and HR-EI-MS analysis.