Influence of the hydrogen bond on the iteroselective O-alkylation of calix[4]resorcinarenes

Synthesis of calixresorcarenes using magnetic poly triazine-benzene sulfonamide-SO3H

“…13 C NMR (75 MHz, DMSO- d 6 ) δ ppm: 55.26, 59.35, 102.38, 106.69, 113.19, 121.22, 129.91, 138.19, 152.84, 156.96. 30 MS: m / z = 920 [M+].…”

Efficient Separation of C-Tetramethylcalix[4]resorcinarene Conformers by Means of Reversed-Phase Solid-Phase Extraction

“…This allows hydrogen bonding with the bpe dimers that are redirected into the cavity to facilitate bond formation. However, sometimes under different synthesis conditions, the presence of conformer mixtures is reported, which makes it difficult to properly characterize each of the products, and there are frequent difficulties for separation since the reaction product behaves as a single compound viewed through TLC and liquid chromatography (LC), but the 1 H NMR and 13 C NMR spectrum is consistent with there being two isomers.…”

“…For most of the cases reported in the synthesis of C -tetramethylcalix­[4]­resorcinarene, the most stable conformation is the crown type. It is established from the deep cavities formed and their stabilization by means of hydrogen bonds mediated by the hydroxyl groups present. − Other unusual conformations have been reported, such as rcct -diamond for C -tetramethylcalix­[4]­resorcinarene, which is rarely observed, and the rcct -boat for C -tetramethyl-2-nitrocalix­[4]­resorcinarene . In the C4 v conformation, intramolecular hydrogen bonds between adjacent phenolic hydroxyl groups preserve the crown structure.…”

Iteroselectivity, the missing sibling of chemo-, regio- and stereoselectivities

“…In 2014, we proposed to name this selectivity "iteroselectivity" 5 and, since then, this term was used in various articles. 6,7,8,9,10,11,12,13,14 To the best of our knowledge, the concepts arising from this type of selectivity have not been yet properly named and defined in the literature.…”