4-(2,4-dihydroxyphenyl)-2,2,4-trimethylchroman: A diol counterpart of Dianin’s compound

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

“…The heterocyclic chroman ring in both compounds adopts an envelope conformation or E form, with atom C2 displaced from the mean plane defined by atoms O1(S1)/C10/C5/C4/C3 by 0.641 (1) and 0.809 (2) Å , respectively, which are directly comparable with the displacements of À0.649 and À0.647 Å found for atom C2 for the 4-hydroxyphenyl and 2,4-dihydroxyphenyl analogues, respectively. In marked contrast, the conformation of the heterocyclic chroman ring in the racemic forms of (I) and (II) (Beresford et al, 1999) is best described as a half-chair or H form, with atoms C2 and C3 displaced from the mean plane defined by atoms O1/C10/C5/C4 by 0.331 (2) and À0.352 (2) Å for (I), and 0.384 (3) and À0.317 (3) Å for (II). A change in the magnitude of the C2-C3-C4-C11 torsion angle from ca 80 in the racemic forms of (I) and (II) to ca 150 in the pure enantiomers leads to very short intramolecular contacts between the syn-related methyl groups, C17 and C18, of 3.287, 3.325 (3), 3.314 (2) and 3.419 (2) Å for (I)-(IV), respectively, which are all less than the sum of the van der Waals radii of 4 Å (Chang, 2000).…”

“…Compounds (III) and (IV) (Figs. 1 and 2) are isostructural not only with each other but also, suprisingly, with the enantiomerically pure forms of the 4-(4-hydroxyphenyl)-, (I) (Lloyd & Bredenkamp, 2005), and 4-(2,4-dihydroxyphenyl)-2,2,4-trimethylchroman, (II) (Beresford et al, 1999), analogues. Crystals of both (III) and (IV) were obtained by spontaneous resolution on crystallization, yielding a 50:50 mixture of the pure enantiomers.…”

“…As part of our continuing studies of the structural properties of materials that demonstrate a close relationship with Dianin's compound [4-(4-hydroxyphenyl)-2,2,4-trimethylchroman], (I), we have focused on how small incremental changes to the scaffold of Dianin's compound can affect the crystal engineering properties of this classic host-guest material (Hardy et al, 1977(Hardy et al, , 1979Beresford et al, 1999;Frampton et al, 1992) [structural data for (I), together with ellipsoid and packing plots, are available in the Supplementary material]. In its racemic form, Dianin's compound and its thiaand selenachroman analogues (Hardy et al, 1979;MacNicol et al, 1969MacNicol et al, , 1987MacNicol & Wilson, 1971) form a series of isomorphous and isostructural clathrates having the common space group R3 with approximate cell paramenters a = 27 Å and c = 11 Å .…”

Engineering robust polar chiral clathrate crystals

“…The results for the former analysis on dextrorotatory 3 which has the R configuration (vide infra) are in complete accordance with the elegant assignment by Collet and Jacques 14 of the absolute configuration for S-(-)-Dianin's compound, the opposite enantiomer; and also consistent with the crystal structure of the S-enantiomer prepared from (S,S)-4-(2,2,4-trimethylchroman-4-yl)phenyl camphanate 15 . The crystal stuctures of 3 and 4, (Figures 1a and 1b), are both isostructural and isomorphous with each other and also with the enantiomerically pure forms of 4-(2,4-dihydroxyphenyl)-2,2,4-trimethylchroman 16 17 in the orthorhombic space group P2 1 2 1 2 1 , with Z = 4. For both compounds the heterocyclic chroman ring adopts an envelope conformation or E-form with atom C2 displaced from from the mean plane defined by atoms O1/S1, C10, C5, C4, C3 by -0.647 and -0.805(2) Å respectively which is directly comparable with the displacements of -0.…”

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

“…This perception was buttressed by the knowledge that many host molecules structurally related to 1 and 2 also form isomorphous, although not in all cases isostructural, host lattices which are analogous to those of 1 and 2, invariably with Z′(host) = 1. Examples of such hosts are the selenachroman 3; 10 4-p-mercaptophenyl-2,2,4-trimethylchroman; 11 methyl-substituted counterparts of 2 with 2,2,4,6and 2,2,4,8-tetramethyl distributions; 4 the resorcinol 4-(2,4dihydroxyphenyl)-2,2,4-trimethylchroman; 12 and a 2-normethyl analogue 13 of 1. The first indication that this packing might not, in fact, represent a unique clathrate potential energy minimum came from the reported unit cell dimensions 10 of the EtOH clathrate of 3, which showed relative to the expected dimensions, c essentially remained unchanged but a effectively doubled with a = 57.42(1) Å and c = 10.871(1) Å; however, all attempts to solve this structure were unsuccessful owing to the fact that only X-ray photographic data were available at that time.…”