Pd-katalysierte asymmetrische Synthese allylischer Sulfone und Stereochemie der Lithiumsalze chiraler allylischer Alpha-tert-Butylsulfonyl-Carbanionen

The Pd(0)-catalyzed allylic sulfonation of allylic substrates with Lithium tert-Butylsulfinate in presence of chiral bisphospines leads to chiral allylic tert-Butylallylsulfones in high yields up to 96% and selectivities up to 98%. Deprotonation of said compounds in alpha-position to their sulfonyl-group forms alpha-tert-Butylsulfonylcarbanions, which are characterized by a hindered rotation around the alpha-C-S-bond and consequently configurative stability at appropriately low temperatures. Last-named renders the chiral anionic species capable for enantioselective C-C-bond formation with reactive electrophiles. The present work particularly deals with structural investigations of Lithium salts of alpha-tert-Butylsulfonylcarbanions in crystal as well as in solution and with the approximation and improvement of their configurative stability