From Central to Helical Chirality: Synthesis of P and M Enantiomers of [5]Helicenequinones and Bisquinones from (SS)‐2‐(p‐Tolylsulfinyl)‐ 1,4‐benzoquinone

Abstract
The reaction of 1,4-divinyl-1,3-cyclohexadiene, 5,8-dimethoxy- or tert-butyldimethylsilyloxy-3-vinyl-1,2-dihydrophenanthrene or 6-vinyl-7,8-dihydro-1,4-phenanthrenequinone with an excess of enantiopure (SS)-2-(p-tolylsulfinyl)-1,4-benzoquinone (2) led to the direct formation of enantioenriched dihydro[5]helicenequinones or bisquinones (50→98 % ee). A domino Diels–Alder cycloaddition/sulfoxide elimination/partial aromatization process occurs, being the absolute configuration of the final helicene defined in the aromatization step. Both M and P helimers are accessible through a stepwise enantiodivergent process if the pentacyclic dihydroaromatic intermediate resulting in the two first steps is aromatized in the presence of (±)-2, DDQ, CAN or DBU.