Seisho Tobinaga

Total synthesis of the alkloids (±)-oxocrinine and (±)-oxomaritidine via anodic oxidation

(±)-Oxocrinine (5a) and (±)-oxomaritidine (5b) were synthesized by anodic oxidation of the trifluroacetyl derivatives of N-(4-methoxyphenethyl)-3,4-methylenedioxybenzylamine (3a) and N-(4-methoxyphenethyl)3,4-dimethoxybenzylamine (3b) followed by hydrolysis.

A new synthesis of the alkaloid (±)-colchicine

The alkaloid (±)-colchicine (1) was synthesized by a methylene transfer reaction from the spirodienone (3b), followed by acid catalysed rearrangement and dehydrogenation to give deacetamido-isocolchicine (7).

Involvement of testosterone in the induction of hepatic microsomal cytochrome P-450 2B1/2 (P-450 2B1/2) by 1-benzylimidazole in male and female rats: sex-differentiated induction of P-450 2B1/2 species.

We examined the effect of 1-benzylimidazole on the induction of cytochrome P-450 1A1/2 (P-450 1A1/2) and cytochrome P-450 2B1/2 (P-450 2B1/2) in normal, castrated, ovariectomized and hypophysectomized male rats, and in castrated rats treated with testosterone. 1-Benzylimidazole markedly increased P-450 content in male and female rats. Parallel to the dose-dependent increase in P-450 content, 1-benzylimidazole produced a significant increase in P-450 2B1/2 in male rats, but not in female rats. 1-Benzylimidazole failed to induce P-450 2B1/2 in castrated male and ovariectomized female rats. Treatment of castrated male rats with testosterone restored the induction of P-450 2B1/2 by 1-benzylimidazole. Treatment of ovariectomized female rats with 1-benzylimidazole or phenobarbital led to the increase in P-450 content, accompanying by the induction of P-450 2B1/2 by the latter treatment, but not the former. In hypophysectomized male rats, 1-benzylimidazole was able to induce P-450 2B1/2 in contrast to castrated male rats. Neonatal male and female rats responded well to the induction of P-450 2B1/2 by 1-benzylimidazole. The present findings suggest that P-450 2B1/2 induction by 1-benzylimidazole would be coupled with circulating testosterone regulated by hypophysis-testis axis. 1-Benzylimidazole produced sex-differentiated induction of P-450 2B1/2 in pubertal rats, but not in neonatal animals. The present findings would be provide information on a unique effect of 1-benzylimidazole on P-450 2B1/2 induction in rats.

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

Biogenetic-type synthesis of (±)-phyllodulcin, a sweet principle of Hydrangea serrata seringe var. thunbergii sugimoto

The synthesis of (±)-phyllodulcin (12), a sweet principle of Hydrangea serrata Seringe var. thunbergii Sugimoto, from 3-(3-benzyloxy-4-methoxyphenyl)prop-2-enal modelled on the polyketide mode of biosynthesis is described.

Reaction of an enamine with 3-acetyl-2-hydroxy-6-methylpyran-4-one, a new synthetic route to β-triketone derivatives

The reaction of 1-morpholinocyclohex-1-ene with 3-acetyl-2-hydroxy-6-methylpyran-4-one (dehydroacetic acid) gave a condensation product (I), which was transformed subsequently into the 4-pyrone (V) and the β-triketone (VII).

New reagent system containing CrO3 and syntheses of neo-lignans

Oxidations of 1-arylprop-1-enes by the new reagent systems, CrO3–HBF4–MeCN or CrO3–HCIO4–MeCN gave the 4-aryltetraiones (1a) and (1c), and the tetrahydrofuran (3) which are precursor molecules for aryltetrahydronaphthalene and tetrahydrofuran neo-lignans.