Several new synthetic reactions have been established which are useful to the synthesis of certain important natural products : (1) stereoselective formation of trisubstituted (
E) -olefins by means of, π-allylic nickel bromide complexes, (2) stereoselective formation of trisubstituted (
E) -allylic alcohols via [2, 3] sigmatropic rearrangement of α-isopropenylamine
N-oxides, (3) stereoselective formation of trisubstituted (
Z) -allylic alcohols via the Wittig reaction of unstabilized ylids with alkoxyacetones, (4) stereoselective synthesis of trisubstituted (
Z) -allylic alcohols via nucleophilic ring opening of
erythro-α-methyl-α, β-epoxy alcohols followed by
cis-elimination of the resulting 1, 2-glycols, (5) stereospecific coupling of (
E) -and (
Z) -polyprenyl aryl sulfones with trisubstituted (
Z) -allylic chlorides in the presence of PTC and aq. sodium hydroxide, and (6)
ortho-selective alkylation of phenols by means of [2, 3] sigmatropic rearrangement of phenoxyisopropylsulfonium alkylids. They provide promising tools to manipulate acyclic terpenoids at the head or terminal position stereoselectively by the aid of easily accessible reagents under mild reaction conditions. Thus the stereoselective synthesis of the following three kinds of natural isoprenoids, i.e., isoprenoid quinones such as coenzyme Q
10 and vitamin K, natural polyprenols which include betulaprenol, bacterialprenol and (
S) -dolichol, and natural
d-α-tocopherol (vitamin E) has been achieved by the application of the above methodologies.
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