60 中国産Curcuma wenyujin(温郁金)の根茎の精油から単離された数種のセスキテルペン成分の絶対構造とその生合成的関連性

概要

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The complete stereostructures of the major hemiacetal sesquiterpene, curcumol, its biogenetic precursor, curdione and spirocyclopentanolide, curcumalactone isolated from Curcuma wenyujin were unequivocally determined as shown in 2a, 5a and 7a, respectively, on the basis of ^1H-NMR, CD and biogenetic consideration as well as X-ray analyses. The conformational analysis of curdione was investigated based on the 400MHz ^1H-NMR variable-temperature and NOE measurements, especially at -70℃, and the preferred conformation of 5a in solution was found to be CC/syn (C(5)=O/C(1)-H) (A) rather than CC/anti (B), the former of which coincided with that in crystal. Curdione, 5a was exclusively converted to curcumol, 2a merely by heating at 200℃ in ethanol, and curcumalactone, 7a solely transformed in chloroform solution at ambient temperature, (especially in the presence of a catalytic amount of hydrochloric acid) by the regio- and stereoselective concerted manner. The above chemical transformations as well as MM2' calculations of 2a, 2b, 5a and 5b enables us to propose a probable pathway from 5a through conformational change (A→B) to 2a, and that (A→C→D) to 7a, respectively. 7-epicurcumalactone, 7b was prepared for a study of the biogenetic consideration.
天然有機化合物討論会の論文
1985-09-07