Easy Synthesis of Functionalized Hetero[7]helicenes.

Hetero[7]helicenebisquinones can be synthesized easily on a multigram scale by combining the silyl enol ethers of 3,6-diacetyldibenzofuran, 3,6-diacetyldibenzothiophene, and 3,6-diacetylcarbazole with p-benzoquinone. They can be resolved into their enantiomers by a procedure that had previously been used to resolve carbohelicenebisquinones. Their absolute configurations are assigned.