Efficient Synthesis of Functionalized [7]Helicenes

J Org Chem. 1998 Oct 16;63(21):7456-7462. doi: 10.1021/jo981380y.

Abstract

[7]Helicenebisquinones can be made easily and in quantity by reacting the silyl enol ethers of a 9,10-dialkoxy-, or better a 9,10-disiloxy-, 3,6-diacetylphenanthrene, with p-benzoquinone. If an ethyl enol ether is used in place of the silyl enol ether, the transformation proceeds in much lower yield. The [7]helicenes are efficiently resolved into their enantiomers, and absolute configurations are assigned.