(<i>R</i>)-4-(4-Aminophenyl)-2,2,4-trimethylchroman and (<i>S</i>)-4-(4-aminophenyl)-2,2,4-trimethylthiachroman

Frampton, Christopher S.; MacNicol, David D.; Wilson, Derek R.

doi:10.1107/s0108270111012157

Cited by 7 publications

(7 citation statements)

References 21 publications

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“…The compounds fa3259 (Waltenberger et al, 2011; Friedif stat = 36) and bm3104III (Frampton et al, 2011; Friedif stat = 22) are examples of careful work from the user community in pharmacy. Their compounds contain only light atoms and the interest was to determine the absolute configuration of the molecule through the determination of the absolute structure of the crystal.…”

Section: Discussionmentioning

confidence: 99%

Absolute-structure reports

Flack

2013

Acta Crystallogr C

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All the 139 noncentrosymmetric crystal structures published in Acta Crystallographica Section C between January 2011 and November 2012 inclusive have been used as the basis of a detailed study of the reporting of absolute structure. These structure determinations cover a wide range of space groups, chemical composition and resonant-scattering contribution. Defining A and D as the average and difference of the intensities of Friedel opposites, their level of fit has been examined using 2AD and selected-D plots. It was found, regardless of the expected resonant-scattering contribution to Friedel opposites, that the Friedel-difference intensities are often dominated by random uncertainty and systematic error. An analysis of data collection strategy is provided. It is found that crystal-structure determinations resulting in a Flack parameter close to 0.5 may not necessarily be from crystals twinned by inversion. Friedifstat is shown to be a robust estimator of the resonant-scattering contribution to Friedel opposites, very little affected by the particular space group of a structure nor by the occupation of special positions. There is considerable confusion in the text of papers presenting achiral noncentrosymmetric crystal structures. Recommendations are provided for the optimal way of treating noncentrosymmetric crystal structures for which the experimenter has no interest in determining the absolute structure.

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Section: Discussionmentioning

confidence: 99%

Absolute-structure reports

Flack

2013

Acta Crystallogr C

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“…of which were obtained by spontaneous resolution (Frampton et al, 2011), and also surprisingly isostructural with the enantiomerically pure forms of 4-(4-hydroxyphenyl)-2,2,4trimethylchroman, 2 (Lloyd & Bredenkamp, 2005) and 4-(2,4dihydroxyphenyl)-2,2,4-trimethylchroman, 5 (Beresford et al, 1999). The crystal packing is dominated by the formation of an extended linear hydroxy -OH to sulfoxide O, hydrogenbonded O-HÁ Á ÁO chain along the [010] direction of the unit cell, Figs.…”

Section: Figurementioning

confidence: 99%

The first spontaneous resolution of a sulfoxide: Dianin's compound analogue, (R)-4-(4-hydroxyphenyl)-2,2,4-trimethylthiachroman-1-oxide

et al. 2018

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“…An important feature of the conformation of all the host molecules described above is the proximal relationship of the p-hydroxyphenyl substituent and its syn related methyl group; it may be noted that this conformation avoids a short contact between the syn related which is present in the structures of the enantiomerically pure non-solvated components. 17,19 In all the isomorphous clathrate structures described above there are columns located on the three-fold proper rotation axis, comprised of infinitely stacked hexameric host units. Throughout the transformations, all host molecules of a given conformation maintain a fixed uniform distribution with respect to the c-axial direction.…”

Section: Quasiracematementioning

confidence: 99%

An unprecedented Dianin clathrate structure with Z′(host) = 16

et al. 2017

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The structure of the iso-propanol clathrate of 4-p-hydroxyphenyl 2,2,4-trimethylthiachroman, the direct thia-analogue of Dianin's compound, has been studied by single-crystal X-ray diffraction as a function of temperature from 371 K down to 90 K. The standard Dianin unit cell, observed at high temperature, undergoes two sequential commensurate thermal phase transformations which results at low temperature in a unit cell with 16 times the original volume and with Z′(host) = 16 and Z = 288, the space group R3 being retained. This ultimate unit cell with a quadrupled a-axis has a = 111.7910Ĳ5) Å and c = 10.8568(1) Å and the crystal packing now features not only the prototypal [OH] 6 hexamer host unit but also novel hydrogenbonded octameric host-guest units with respective symmetries C i and C 1. In addition it has been established that the corresponding achiral selena-Dianin's clathrate and the polar chiral quasiracemic isopropanol clathrate, space group R3, formed from R-Dianin's and S-thia-Dianin's components also exhibit novel related temperature-dependant behaviour.

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(R)-4-(4-Aminophenyl)-2,2,4-trimethylchroman and (S)-4-(4-aminophenyl)-2,2,4-trimethylthiachroman

Cited by 7 publications

References 21 publications

Absolute-structure reports

Absolute-structure reports

The first spontaneous resolution of a sulfoxide: Dianin's compound analogue, (R)-4-(4-hydroxyphenyl)-2,2,4-trimethylthiachroman-1-oxide

An unprecedented Dianin clathrate structure with Z′(host) = 16

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