Chiral discrimination of 2-heptlyaminium salt by planar-chiral monohydroxy-functionalized pillar[5]arenes

Abstract

A chiral receptor was synthesized based on monohydroxy-functionalized pillar[5]arenes and its ability to discriminate alkyl aminium salts is demonstrated.

Concentration-dependent supramolecular self-assembly of A1/A2-asymmetric-difunctionalized pillar[5]arene

“…Recently, difunctionalized pillar[5]arene with hydroxy and amino groups at the A1/A2 have been synthesized by controlled de- O -methylation of permethylated pillar[5]arene using oxidation-followed-by-reduction strategy. 17 Taking advantage of our previously report approach for the synthesis of hydroxylated pillar[5]arenes, 11 a series of asymmetric A1/A2 difunctionalized pillar[5]arenes were synthesized. The approach involves co-cyclization of hydroquinone derivatives of 1,4-dimethoxybenzene and 1-benzyloxy-4-bromoalkoxybenzenes with paraformaldehyde in the presence of BF 3 ·OEt 2 , as shown in Scheme 1 .…”

“…4-Benzyloxyphenol was synthesized according to literature procedure. 11 DMF, acetonitrile and dichloroethane were distilled before use. All other reagents and solvents were of reagent grade purity and used without further purification.…”

Synthesis, functionalization, and isolation of planar-chiral pillar[5]arenes with bulky substituents using a chiral derivatization agent

“…Therefore, using our previously reported strategy 15 we attempted co-cyclization with a benzoxycontaining monomer, which enabled derivatization with a chiral agent ((S)-(+)-Mosher's acid chloride) aer complete removal of the benzyl group by catalytic hydrogenation, as shown in Scheme 2. 16 TLC analysis of synthesized Pillar-4 showed two spots with equal intensities, which were isolated by silica gel column chromatography. Fig.…”

Spontaneous and induced chiral symmetry breaking of stereolabile pillar[5]arene derivatives upon crystallisation

“…Enantiomeric P[5] conformers 8 are interconvertible to each other through a series of oxygen-through-the-annulus flipping motions of their aromatic units. 9 By introducing either bulky substituents on the rims, 10 or mechanically-interlocked structures using P[5]s as the ring component, 11 the inversion processes of P[5]s can be completely inhibited, therefore enabling the isolation of two types of atropisomers by classical resolution methods or with the help of HPLC with chiral stationary phases. On the other hand, stereolabile P[5]s with low-to-moderate inversion barriers exist in solution as optically-inactive ensembles of fluxional conformers.…”