Overview of the Synthesis and Structure of Calix[n]quinones (n=4, 6, 8).

Calix[n]quinones, a class of cyclic oligomers composed of p-benzoquinone structures connected by methylene, have multi-conjugated carbonyl structures and adjustable cavities, which make their synthesis extremely attractive. In this minireview, synthetic methods of calix[n]quinones and recent synthetic experience of our group are summarized. The merits and demerits of various synthetic methods are briefly reviewed as well. When synthesizing calix[n]quinone (n≥6) with a larger ring, the reduction-oxidation method is considered to be the most recommended.