New Phosphite-Oxazoline Ligands for Efficient Pd-Catalyzed Substitution Reactions

摘要

Palladium-catalyzed asymmetric allylic substitution is a versatile,widely used process in organic synthesis for the enantioselective formation of C-C and C-heteroatom bonds.The past decade has seen a huge advance in enantiocontrol in the Pd-catalyzed allylic substitution reactions.However,the catalytic systems developed to date generally have two important drawbacks (Figure 1).First,they show a high substrate specificity (i.e.,high ee's are obtained in disubstituted linear hindered substrates and low ee's are obtained in cyclic and unhindered linear substrates,or vice versa).Second,the reaction rates are usually low (i.e.,usually TOF's <= 100 mol centre dot mol centre dot h)~(-1)).