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Transformations of helenalin : crystal structure analysis of the oxide from the reaction with hydrogen chloride

✍ Scribed by Andrew T. Mcphail; Key D. Onan; Kuo-Hsiung Lee; Hiroshi Furukawa; Sun-Hyuk Kim; Claude Piantadosi

Publisher
Elsevier Science
Year
1973
Tongue
French
Weight
140 KB
Volume
14
Category
Article
ISSN
0040-4039

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✦ Synopsis

During the course of the recent re-investigations1 on the reactions of helenalin(1) with hydrogen chloride-chloroform and deactivated neutral alumina a new crystalline oxide having composition Cl5 H 0 was obtained in addition to the known mexicanin A(111 and 18 k 1-epiallohelenalin(II1). In contrast to earlier reports 2-4 , no neohelenalin(IV) was found to be produced under these conditions. Structures (V) and (VI) were postulated for this new compound with the former being favored on the basis of reactions and spectra but definite structure proof was not obtained. Since the structure and stereochemistry of the oxide bear on the mechanism of transformations between the above compounds, we have subjected it to single crystal X-ray analysis in order to define its constitution unambiguously.

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