Chiral Pyridinyloxazolidine Ligands for the Pd-Catalyzed Asymmetric Allylic Alkylation

Abstract

Asymmetric carbon-carbon bond-forming reaction is one of the most valuable processes for construction of enantiomerically enriched molecules. Considerable research has been done on Pd-catalyzed asymmetric allylic alkylation. In particular, the search of new chiral ligands is an important chapter in the area and remains an area of intense research. We have previously found that phosphinooxazolidines 1 bearing sp nitrogen donor are useful ligands in the asymmetric allylic alkylation. The oxazolidines obtainable by simple synthetic route seem to be potential ligands for the asymmetric catalysis. As part of our continuing interest in oxazolidines, we herein disclose the preparation of new chiral pyridinyloxazolidines and their application in asymmetric allylic alkylation. The oxazolidines 2-4 were obtained through condensation of commercially available 2-pyridinecarboxaldehyde and optically pure (S)-N-methylalaninol, (S)-N-methylvalinol and (1R,2S)-ephedrine in good yields of 80%, 84%, and 90% respectively. The reaction leads to the formation of new