Investigations into the enantioselective C-protonation of prostereogenic enolate(s) derived from N,N′-diisopropyl-2-phenylpropanamide using suicide C-based proton sources

The synthesis of enantiomerically enriched (−)-(R)-N, N′-diisopropyl-2-phenylpropanamide was achieved in up to 69% enantiomeric excess by symmetrisation of the corresponding racemic amide by addition of sec-BuLi (to give the corresponding achiral lithium enolate) and subsequent desymmetrisation by the addition of a chiral C-based proton source. We discuss potential factors that may be responsible for this observed enantioselectivity and comment on the role of the chiral acid.