Efficient asymmetric synthesis of [7]helicene bisquinones

The efficient one-pot six-step domino process which occurs when (SS)-2-(p-tolylsulfinyl)-1,4-benzoquinone (1) reacts with 3,6-divinyl-1,2,7,8-tetrahydrophenanthrenes 2a-c allowed enantioselective access to [7] helicene bisquinones 3a-c with excellent optical purities (96 to >99% ee).