Efficient Synthesis of Functionalized [7]Helicenes.
[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.
Fox
Joseph M.
JM
Department of Chemistry, Columbia University, New York, New York 10027.
Goldberg
Naomi R.
NR
Katz
Thomas J.
TJ