Triple Thorpe–Ingold Effect in the Synthesis of 18‐Membered C₃ Symmetric Lactams Stacking as Endless Supramolecular Tubes

Abstract

Three C 3 symmetric macrolactams were very efficiently cyclized from their linear precursors. Adequately located substituents are responsible for the enhancement of reactivity that is not observed in the unsubstituted parent. DFT calculations show that the properly folded cyclization precursor, the reactive conformer, is more populated than other conformers, leading to a decrease of free energy of activation. The crystal structure of the ring substituted with three very bulky esters indicates that tubular stacking is preserved.

Modulating the shuttling motion of [2]rotaxanes built of p-xylylenediamine units through permethylation at the benzylic positions of the ring

“…Previous reports have shown the benefits of the Thorpe–Ingold effect in related [2 + 2] macrocyclization processes. 17 However, this low yield, compared to the one previously reported by using the parent p -xylylenediamine (97%) suggests the instability of the supramolecular intermediates leading to the rotaxane 7 and the apparently moderate affinity of the octamethylated macrocycle for the fumaramide binding site. The introduction of the methyl groups at the ring could affect the electronics of its amide functions playing a key role during the supramolecular recognition between the rotaxane precursors.…”

Hydrogen‐Bonded Organic Frameworks Based on Endless‐Stacked Amides for Iodine Capture and Detection

“…[31,32] The self-assembly of specific building blocks via noncovalent interactions into various well-defined architectures such as 1D columns, 2D layered networks and 3D PMCs has been demonstrated in a myriad of examples. [9,[33][34][35][36][37][38][39][40] Among those, hydrogen-bonded organic frameworks (HOFs) have rapidly become an important class of welldefined PMCs connected by H-bond and which exhibit high crystallinity, recyclability and simple preparation conditions. [38][39][40][41][42][43][44][45] However, the weaker nature of H-bond compared to covalent bonds remains a hurdle in the construction of HOFs with permanent porosity.…”