Letter | Published:

Ring Structure of Calciferol



ALTHOUGH calciferol has been shown to be isomeric with ergosterol (C28H44O), comparatively little information has hitherto been adduced concerning the detailed structure of this vitamin. According to Windaus, Linsert, Lüttringhaus and Weidlich1 (compare also Askew et alia2) perbenzoic acid titration shows the presence of three ethenoid linkages, from which it follows that calciferol contains a tetracyclic ring structure. In contrast to this observation, Kuhn and Möller3 have found by hydrogenation that calciferol contains four ethenoid linkages, a result which we have confirmed. Calciferol cannot therefore be a tetracyclic compound. Further evidence in support of this view arises from the work of Lettré4, who on dehydrogenation of calciferol failed to obtain Diel's hydrocarbon (C18H16). Again, this author has demonstrated that tachysterol, which is a direct intermediate in the photochemical conversion of ergosterol into calciferol, is also tricyclic, probably having the constitution I or II.

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  1. 1

    Ann., 492, 226 ; 1932.

  2. 2

    Proc. Roy. Soc., B, 108, 340 ; 1931.

  3. 3

    Z. angew. Chem., 47, 145 ; 1934.

  4. 4

    Ann., 511, 280 ; 1934.

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