13 有機化合物の絶対構造 : クレロダン系ジテルペンの基本化合物Clerodinの絶対構造の逆転について

概要

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The absolute stereochemistries of clerodane diterpenes, clerodin (3), caryoptin (14), and 3-epicaryoptin (15) previously determined by X-ray and related chemical studies have been reversed on the basis of the exciton chirality circular dichroism and molecular rotation difference data. The 3-epicaryoptin derivative bis(p-chlorobenzoate) (22) previously assigned is antipodal to the model compound of 5α-cholestane-3β,4α,6α-triol 3,6-bis(p-chlorobenzoate) (29) in principal chiral centers. However, comparison of the CD exciton coupling Cotton effects of dibenzoate 22, λ_<ext> 247.5 nm, Δε+17.8/230 nm, Δε-9.2 and 29, λ_<ext>246.2 nm, Δε+27.0/ 231.0 nm, Δε-13.8, has led to the conclusion that the absolute configuration of 3-epicaryoptin should be revised and expressed in the enantiomeric form of 15. The same is true in the case of caryoptin 14. Comparison of the molecular rotation difference data, Δ[φ]_D, of a series of clerodin, caryoptin, 3-epicaryoptin, and clerodendrin A (9) derivatives has confirmed the above assignment, indicating that the absolute configuration of clerodin also should be revised and expressed in the enantiomeric form of 3.
天然有機化合物討論会の論文
1979-09-20