Ketocalixarenes: Versatile yet still Unexplored Macrocycles

Ketocalix[n]arenes can be prepared via oxidation of the methylene groups of protected calix[n]arenes. The presence of carbonyl groups at the bridges alters the preferred conformation and reactivity of the macrocycle and provides an entry point (via nucleophilic additions reactions) to a wide array of methylene-substituted derivatives as well as calix[n]radialenes.

1 Introduction

2 Synthesis of Ketocalix[n]arenes

2.1 Ketocalix[4]arene Derivatives

2.2 Systems Possessing both Carbonyl and Bromomethane Bridges

2.3 Pentaoxoketocalix[5]arene and Hexaoxoketocalix[6]arene Derivatives

2.4 Monooxo- and Dioxoketocalix[6]arenes

3 Conformation of Ketocalixarenes

4 Reactions of Ketocalixarenes

4.1 Alkylation of the OH Groups

4.2 Intramolecular Aromatic Nucleophilic Substitution

4.3 Reduction of the Carbonyl Groups

4.4 Reaction of 5c with PhLi

4.5 Reaction with tert-Butyllithium

5 From Ketocalix[n]arenes to Calix[n]radialenes and Calix[n]rotanes

6 Summary and Outlook