A Se···O bonding catalysis approach to the synthesis of calix[4]pyrroles

Abstract

Described herein is a chalcogen bonding catalysis approach to the synthesis of calix[4]pyrrole derivatives. The Se···O bonding interactions between selenide catalysts and ketones gave rise to the catalytic activity in the condensation reactions between pyrrole and ketones, leading to the generation of calix[4]pyrrole derivatives in moderate to high yields. This chalcogen bonding catalysis approach was efficient since only 5 mol % catalyst loading was used to promote the consecutive condensation processes while the reactions could be carried out at room temperature, thus highlighting the potential of this type of nonclassical interactions in catalyzing relative complex transformations.

Recent developments in calix[4]pyrrole (C4P)-based supramolecular functional systems

“…44 Furthermore, recently, Wang and co-workers assembled various simple and functionalized C4P structures utilizing the chalcogen bonding (Se⋯O)-catalytic approach. 45 Conversely, from a biological viewpoint, besides acting as handy ion-transporters across the lipid bilayer membrane to treat defective ion channels, 46–48 C4P-based systems serve as drug carriers for the targeted defective tissues of the body, and also participate in pharmaceutical treatments in combating deadly diseases. 49,50 Moreover, these functional materials have also been exploited in the field of sensing for a wide range of anions, metal ions, and neutral molecules, 51–55 polymers, 56 catalysis, 57,58 polymorphism, 59 molecular machines, 60,61 molecular switches, 62–65 molecular probes, 66 metal ion coordination cages, 67 organic solar cells, 68 hydrogen sorption, 69 and adsorption of pollutants.…”

“…44 Furthermore, recently, Wang and co-workers assembled various simple and functionalized C4P structures utilizing the chalcogen bonding (Se⋯O)-catalytic approach. 45 Conversely, from a biological viewpoint, besides acting as handy ion-transporters across the lipid bilayer membrane to treat defective ion channels, [46][47][48] Organic and Supramolecular Functional Materials Research Laboratory, Department of Chemistry, Jamia Millia Islamia, Jamia Nagar, Okhla, New Delhi-110025, India. E-mail: rali1@jmi.ac.in; Tel: +91-7011867613 C4P-based systems serve as drug carriers for the targeted defective tissues of the body, and also participate in pharmaceutical treatments in combating deadly diseases.…”

“…Basically, N-oxides are promising candidates as pharmaceutical agents and also act as neutral polar guests for various processes. 83 Thus, considering the importance of N-oxides, Sessler and other collaborating research groups described the recognition of pyrazine-N,N′-dioxide (45) in the solid state and in solution phase by virtue of 2/4-walled aryl extended-C4Ps (38-42, Fig. 5).…”

“…5). 84 Single-crystal X-ray studies revealed the partial cone conformation of the receptors (38)(39)(40) encapsulating a guest entity (45) in the form of 2 : 1 host-guest complexes (Fig. 5).…”

Supramolecular approaches to mediate chemical reactivity

“…In their contribution Wang and co-workers [17] reported an interesting example of chalcogen bonding catalysis approach for the synthesis of calix [4]pyrrole macrocycles. The Se•••O=C chalcogen bonding interactions between a selenide-based catalyst and the carbonyl-substrate catalyzed the macrocyclization with pyrrole.…”