Masaaki Toda

Daphniphyllum alkaloids—II: Secodaphniphylline and methyl homosecodaphniphyllate☆

Abstract Isolation and structures of two new alkaloids, secodaphniphylline (I) and methyl homosecodaphniphyllate (II), are described. The structure of the latter, established by X-ray analysis of its bromoacetyl derivative, is in full agreement with its chemical and spectral data. The structure of the former was deduced by chemical correlation between I and II. The 2-azabicyclo-[3.3.1]non-1-ene system, an unusually stable anti-Bredts-rule imine, was formed from II.

Total synthesis of (±)aplysin and (±)debromoaplysin

Abstract Aplysin 1 and debromoaplysin 2, sesquiterpenes isolated from Aplysia kurodai were synthesized in racemic form by two routes. Some rearrangement reactions, encountered during the synthetic work, are described.

The alkaloids from the fruits of the plant Daphniphyllaceae

Abstract Six alkaloids have been isolated from the fruits of the plant Daphniphyllaceae . Two of them are new alkaloids, namely methyl homodaphniphyllate ( 1 ) and daphnilactone-B ( 2 ). The structure of the former was deduced by chemical transformation from daphniphylline ( 3 ). The structure of daphnilactone-B was estimated by the exhaustive spectral analysis as well as by chemical evidences, and finally determined by an X-ray crystallographic analysis of the free base.

The structure of prostaglandin B1 dimer

Dimeric derivatives of prostaglandin B1 were prepared under alkaline conditions and the structures were determined by NMR spectroscopies.

Chemical studies on nitrogen heterocyclic skeleton of the Daphniphyllum alkaloids

Abstract From a biogenetic point of view, a great variety of related alkaloids isolated from the plant Daphniphyllaceae are related to one another by bond formation or fission. Thus, daphnialcohol acetate (6), a derivative of the degradation products of daphniphylline (1), was subjected to von Braun degradation followed by acid-catalyzed recyclization to give an isomer (8) of daphnialcohol, which has a new type of nitrogen heterocyclic skeleton. Furthermore, daphnilactone-B (3) was converted into a daphniphylline-type compound (19) via a plausible intermediate (21).

Zinc reductions of keto-steroids

Zinc reductions of keto-groups to methylene groups in such typical organic solvents as diethyl ether and benzene saturated with dry hydrogen chloride have been carried out successfully at 0°(1hr.).