Naoki Takeuchi

Polyacetylenes from Panax quinquefolium

Abstract New C 17 - and C 14 -polyacetylenes, and two known polyacetylenes were isolated from the dried roots of Panax quinquefolium . The structures of the new polyacetylenes were determined by their 1 H and 13 CNMR, and mass spectral data. The C 17 -polyacetylenes exhibited strong cytotoxic activity (IC 50 =0.1≈0.5 μg ml −1 ) against leukaemia cells (L1210) in tissue culture.

Acetylenes from Panax quinquefolium

Abstract Two new C 17 -polyacetylenes and a C 14 -polyacetylene were isolated from dried roots of Panax quinquefolium . Their structures were determined by their 1 H NMR, 13 C NMR and mass spectral data. The cytotoxic activity of C 17 -polyacetylenes against leukemia cells (L 1210) was ca 20 times that of the C 14 -polyacetylene.

Syntheses of dihydroisocoumarins, (±)-hydrangenol and (±)-phyllodulcin, utilizing an annelation reaction of enaminones with ethyl acetoacetate. Studies on the β-carbonyl compounds connected with the β-polyketides. XIII

Naturally occurring dihydroisocoumarins, (±)-hydrangenol (1) and (±)-phyllodulcin (2) were synthesized from the enaminones (3) and (4) by the annelation reactions with ethyl acetoacetate (5)

Synthesis of (+)- and (-)-Mellein Utilkizing an Annelation Reaction of Isoxazoles with Dimethyl 3-Oxoglutarate

Naturally occurring dihydroisocoumarins, (+)- and (−)-mellein (2 and 3), metabolites of fungals, Cercospora sp. and Aspergillus sp., etc., were synthesized from the isoxazoles (32) and (33) by the annelation reactions with dimethyl 3-oxoglutarate

An easy two synthon synthesis of a sweet dihydroisocoumarin, (±)-phyllodulcin

A short synthesis of (±)-phyllodulcin (1), a sweet principle of Hydrangea serrata Seringe var. thunbergii Sugimoto, from the enaminone (2) by annelation with dimethyl 3-oxaglutarate is described.

Condensation reactions of a nitrodienamine with indoles in trifluoroacetic acid

Treatment of a nitrodienamine (1) with indoles in trifluoroacetic acid gave condensation products