Intramolecular S_NAr Reactions in a Large-Ring Ketocalix[6]arene

Ketocalix[6]arene 2e was prepared by CrO₃ oxidation of the methylene groups of 2a, followed by hydrolysis of the acetate groups. 2e undergoes intramolecular S_NAr reactions under the usual methylation conditions (MeI, base), yielding mono- and dixanthone calixarene derivatives.