Regio-and Stereoselective Terminal Allylic Carboxymethylation of gem-Dimethyl Olefins. Synthesis of Biologically Important Linear Degraded Terpenoids

抄録

gem-Dimethyl olefins (III) were transformed regiospecifically to the terminal β-methallyl sulfides (IV) bearing the methoxycarbonylmethyl substituent on the sulfur atom via (A) methoxycarbonylmethanesulfenyl chloride addition followed by dehydrochlorination or (B) allylic chlorination with SO₂Cl₂ followed by sulfenylation with methyl thioglycolate. Treatment of the sulfides (IV) with tert-BuOK or NaH in N, N-dimethylformamide or dimethyl sulfoxide at room temperature gave stereoselectively the sulfur-free esters (V) through a novel one-pot desulfurizative [2, 3]-sigmatropic rearrangement. By utilizing this method, biologically and pharmacologically important linear degraded terpenoids, a diol component (1) of the pheromonal secretion of the queen butterfly and several ω-quinoid acids (4, n=1, 2) and (5, n=1, 2), which are metabolites of polyisoprenoidquinones, were synthesized.