Synthesis of New Schiff Base-Camphorsulfonyl Amide Ligands and in situ Screening in the Asymmetric Additions of Organozinc Reagents to Aldehydes.

We have designed and synthesized a new library of highly modular Schiff base-camphorsulfonyl amide ligands from readily available starting materials. These ligands have been used in the asymmetric addition of diethyl zinc to aldehydes in good yields (up to 91%) and high enantioselectivities (up to 93%). Moreover, when the ligands were used in the asymmetric addition of phenylacetylene to aldehydes, good yields and moderate to high ee values (up to 90%) were obtained. The introduction of the camphorsulfonyl moiety into the ligands is highly critical for the selectivities of the reactions.