The conformation of non-aromatic ring compounds. LXXV. The crystal and molecular structure of the 3,20-bis(ethylenedioxy) analogue of vitamin D

Knobler, Carolyn B.; Romers, C.; Braun, P. B.; Hornstra, J.

doi:10.1107/s056774087200559x

Cited by 36 publications

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“…The conformation about C(17)-C(20) [see Fig. 3(f)] is nearly identical with that found for ECF [Knobler et al (1972), Fig. 4(e)].…”

Section: Molecular Geometrysupporting

confidence: 75%

“…As reported earlier (Knobler et al, 1972), it is very difficult to obtain proper crystals of vitamin D and its * Present address: Chemistry Department, University of California, Los Angeles, California 90024.…”

Section: Methodsmentioning

confidence: 99%

“…& J. H.) calculated a sharpened Patterson function and started their Patterson search program (Braun, Hornstra & Leenhouts, 1969a) with the same model of 9 atoms as used for the solution of the structure of ECF (Knobler et al, 1972).…”

Section: Patterson Search By Computermentioning

confidence: 99%

“…In a previous paper (Knobler, Romers, Braun & Hornstra, 1972) the crystal structure of an analogue of ergocalciferol (hereafter ECF) was described.…”

Section: Introductionmentioning

confidence: 99%

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The conformation of non-aromatic ring compounds. LXXVIII. The crystal and molecular structure of the 3,20-bis(ethylenedioxy) analogue of provitamin D

Braun¹,

Hornstra²,

Knobler³

et al. 1973

Acta Crystallogr Sect B

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Crystals of 3,20-bis(ethylenedioxy)-pregna-5,7-diene are monoclinic, space group P2~. The lattice constants are a= 12.22, b= 6-02, c= 15.77 A, t= 111.9 ° and Z= 2. Owing to pseudo-symmetry the solution of the structure, carried out by Patterson image-seeking methods, was difficult. The refinement, using photographic data, resulted in an R value of 13"1%. Rings A and C have distorted chair conformations, while ring B is an irregular half chair with C(I 0) above and C(9) below the planar moiety of atoms 5, 6, 7 and 8. In terms of torsion angles, the five-membered rings (the two dioxolane rings) have a halfchair conformation and ring D a form halfway between a half-chair and an envelope with C(14) as flap. IntroductionThis paper is part of structural study of steroids in the calciferol series. In a previous paper (Knobler, Romers, Braun & Hornstra, 1972) the crystal structure of an analogue of ergocalciferol (hereafter ECF) was described.The present report deals with its isomer the 3,20-bis-(ethylenedioxy) analogue of ergosterol (provitamin D2, Fig. 1) with the systematic name (IUPAC-IUBo 1969) 3,20-bis(ethylenedioxy)-pregna-5,7-diene (hereafter EPD). Except for the dioxolane rings A' and D' the atoms are numbered according to chemical convention.Because we did not succeed in obtaining proper crystals of the mother compound, ergosterol, we investigated an analogue. The omission of the side group and the introduction of dioxolane rings are, indeed, serious handicaps in the evaluation of the conformational properties of provitamin D2. Nevertheless the eludication of the structure of the chosen analogue is a useful addition to our knowledge of this class of compounds.Another steroid also having a 5,7-diene system is lumisterol. The structure of its m-bromobenzoate ester has been analysed by Hodgkin & Sayre (1952), but the authors gave no information concerning bond lengths and valency angles in the molecule. The structure of lumisterol itself is now being investigated in this laboratory. ExperimentalAs reported earlier (Knobler et al., 1972), it is very difficult to obtain proper crystals of vitamin D and its * Present address: Chemistry Department, University of California, Los Angeles, California 90024.analogues. The crystals of EPD were smaller and less stable to X-radiation than those of ECF and therefore less suitable for extended measurements by diffractometer-counter techniques. The compound crystallizes in colourless rectangular plates (001). The lattice constants (Table 1) were determined at room temperature from oscillation and zero-layer Weissenberg photographs using copper radiation. If the unit cell is assumed to contain two molecules, a density of dx= 1.23 gcm -3 is calculated, a reasonable number compared with the observed value dobs= 1.20 g cm -a obtained for the vitamin D analogue.The reflexions of a crystal with dimensions 0.05, 0.4 and 0-6 mm were recorded at room temperature with non-integrated equi-inclination Weissenberg photographs, using Cu K~ radiation and multiple film-technique. Collected we...

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“…The conformation about C(17)-C(20) [see Fig. 3(f)] is nearly identical with that found for ECF [Knobler et al (1972), Fig. 4(e)].…”

Section: Molecular Geometrysupporting

confidence: 75%

Section: Methodsmentioning

confidence: 99%

Section: Patterson Search By Computermentioning

confidence: 99%

“…In a previous paper (Knobler, Romers, Braun & Hornstra, 1972) the crystal structure of an analogue of ergocalciferol (hereafter ECF) was described.…”

Section: Introductionmentioning

confidence: 99%

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