Palladium‐Catalyzed Highly Enantioselective Arylation of Cyclic N ‐Sulfonyl α‐Ketimino Esters towards the Synthesis of α‐Quaternary Chiral Amino Acid Derivatives

We have developed a highly effective palladium/PHOX catalyst system for efficient asymmetric 1,2‐addition of arylboronic acids to six‐membered 1,2,6‐thiadiazine‐1,1‐dioxide type cyclic N ‐sulfonyl α‐iminoesters. The protocol allows convenient synthesis of a variety of nearly optically pure α‐quaternary amino acid derivatives under mild reaction conditions. The synthetic utility of the reaction is demonstrated by simple product transformations. It allows the convenient construction of α,γ‐substituted chiral γ‐lactams having two carbon stereogenic centres, including one quaternary centre, in a highly enantiomerically pure form. This chemistry may be used to generate analogous molecules of BMS‐561392 for bioactivity screening and drug discovery.