A facile and efficient preparation of pillararenes and a pillarquinone.

Calixarenes 1 and their derivatives have attracted considerable attention over the past two decades. This attention can be attributed to their applications in areas as diverse as gas adsorption, nanotubes, catalysis, DNA recognition and fullerene chemistry. Recently, many calixarene analogues have been developed in supramolecular chemistry, such as calixpyrroles, thiacalixarenes, and homooxacalixarenes. In contrast to the vast literature about the meta-bridged cyclooligomers 1, very little is known about their para-bridged analogues 2, called pillar[n]arenes (Scheme 1). Recently, the