Atroposelective synthesis of axially chiral P,S-ligands based on arynes
Résumé
The first atropo-selective aryl-aryl coupling based on arynes in the presence of a tert-butylsulfinyl group as the chiral auxiliary on the aryllithium nucleophile is described. This approach allows for the efficient access to a novel family of atropo-enantiopure biphenyl-based phosphine-thioether ligands (aR)- and (aS)-I [R = cyclohexyl, Ph]. Moreover, this new P and S donor ligands were assessed in model palladium-catalyzed allylic substitution reactions, showing good enantioselectivity (up to 98 % ee).