Chirality Transfer in Acyclic Allylic Systems and New Pd-Catalyzed Heck Reaction/C-H Activation Cascades
In the first part, the use of chirality transfer in acyclic allylic systems was assessed for an intra- and an intermolecular reaction. The thermal [2,3] sigmatropic rearrangement of acyclic allylic phosphinites proved to be highly enantioselective, even at 110 °C and led to enantiomerically pure allylic phosphine oxides. The substitution pattern of the substrate and the reaction conditions were fully optimized.The chirality transfer concept was also used intermolecularly in asymmetric allylic substitution reactions. This allowed to build up enantiomerically pure quaternary centers. The product were then reacted to obtain enantionerically pure tertiary alcohols, desymmetrized 1,3 diols and aldol compounds. In a second part, it was found that Heck reaction leading to neopentylic palladium species underwent, in the absence of nucleophile, a C-H activation reaction, leading to spiro cyclopropyl compounds.