Hexaarylbenzenes (HABs) are precursors to hexabenzocoronenes, which exhibit liquid crystalline and light-harvesting properties. Several analogs have been prepared that are highly symmetrically substituted, either with six identically substituted aryl groups or with two differently substituted aryl groups. Recently, hexaarylbenzenes with four different aryl substituents have been prepared, but in an ABCDDC substitution pattern which allows selective elaboration of the HABs at the ortho positions. Herein we report the synthesis of heterosubstituted hexaarylbenzenes with an AABCCD substitution pattern. The general synthetic strategy involves the condensation of a diarylacetone with a substituted benzil to give a tetraarylcyclopentadienone, which can then undergo a Diels-Alder cycloaddition with a diarylethyne to give the hexaarylbenzene. However, because both the benzil condensation and Diels-Alder cycloadditions are not regioselective, we have synthesized asymmetrical diarylacetones that give hexaarylbenzenes which have two different substituents at the para positions. Asymmetric Collman carbonylative coupling of two benzyl bromides gives the asymmetrical diarylacetones in decent yields, which have then been condensed with benzil and further elaborated to give the heterosubstituted HABs.
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