Constitutional isomers of brominated-functionalized copillar[5]arenes: synthesis, characterization, and crystal structures

Abstract

Constitutional isomers of brominated-functionalized pillar[5]arenes were synthesized using a co-cyclization strategy.

Spatially Designed Supramolecular Anion Receptors Based on Pillar[5]arene Scaffolds: Synthesis and Halide Anion Binding Properties

“…The synthesis of 1,4-bis(2-bromoethoxy)benzene, 1-(1,4-bis(2-bromoethoxy))-2,3,4,5-dimethoxy-pillar [5]arene, 1,1-Pillar-a, 1,2-(1,4-bis(2bromoethoxy))-3,4,5-dimethoxy-pillar [5]arene, 1,2-Pillar-a, and 1,3-(1,4-bis(2-bromoethoxy))-2,4,5-dimethoxy-pillar [5]arene, 1,3-Pillar-a have been previously discussed. 31 1 H NMR Titration. Briefly, 0.5 mL samples of 1-DUP, 1,2-BUP, and 1,3-BUP solutions were prepared at a concentration of 5.0 mM in DMSO-d 6 .…”

“…The first step in the synthesis of a ureabased anion receptor is the use of suitable functionalized pillar [5]arenes, namely, 1A/2A-dibromoethoxy-pillar [5]arene (1,1-Pillar-a), 1,2-tetrabromoethoxy-pillar [5]arene (1,2-Pillar-a), and 1,3-tetrabromoethoxy-pillar [5]arene (1,3-Pillara). 31 The bromo-functionalized pillar [5]arenes were converted to amino derivatives by the reaction with sodium azide (NaN 3 ), followed by catalytic hydrogenation. The target ureafunctionalized pillar [5]arenes were obtained upon the reaction with p-nitrophenyl benzylcarbamate (Figure 1a).…”

“…On the basis of such systems, constitutional isomers of urea-functionalized pillar[5]­arenes were synthesized following the strategy outlined in Scheme . The first step in the synthesis of a urea-based anion receptor is the use of suitable functionalized pillar[5]­arenes, namely, 1A/2A-dibromoethoxy-pillar[5]­arene ( 1,1-Pillar-a ), 1,2-tetrabromoethoxy-pillar[5]­arene ( 1,2-Pillar-a ), and 1,3-tetrabromoethoxy-pillar[5]­arene ( 1,3-Pillar-a ) . The bromo-functionalized pillar[5]­arenes were converted to amino derivatives by the reaction with sodium azide (NaN 3 ), followed by catalytic hydrogenation.…”

“…All other reagents and solvents were of reagent grade purity and used without further purification. The synthesis of 1,4-bis­(2-bromoethoxy)­benzene, 1-(1,4-bis­(2-bromoethoxy))-2,3,4,5-dimethoxy-pillar[5]­arene, 1,1-Pillar-a , 1,2-(1,4-bis­(2-bromoethoxy))-3,4,5-dimethoxy-pillar[5]­arene, 1,2-Pillar-a , and 1,3-(1,4-bis­(2-bromoethoxy))-2,4,5-dimethoxy-pillar[5]­arene, 1,3-Pillar-a have been previously discussed …”

“…The isolated regioisomers were fully characterized by NMR and MS analyses. The structures of the isomers were assigned when their crystal structures were obtained from X-ray signal crystal diffraction analysis, which showed their different substitutional group distributions . The yield of regioisomers could be controlled through manipulation of the feed ratio of hydroquinone derivatives.…”