Calix[4, 5]tetrolarenes: A New Family of Macrocycles.

The facile and efficient one-step synthesis and the full characterization of novel π-electron rich macrocycles, calix-[n]tetrolarenes (n = 4, 5), are described. The tetramer and the much rarer sized pentamer were easily prepared by reaction of the commercially available, partially methylated 1,2,3,5-benzenetetrol with paraformaldehyde under TFA catalysis, with a total isolated yield of 73%. The reaction is solvent sensitive, and the number of methylated oxygens also affects the tetramer/pentamer distribution. The compounds formed may be considered as "chimeric" macrocycles of calixarene and pyrogallol[n]arene that may serve as new building blocks in host-guest and supramolecular chemistry.