IAN-amines: New reagents for organic and organometallic synthesis

A straightforward synthesis of the first axially chiral beta-diketimine ligands derived from I&barbelow;soquinoline and 2-A&barbelow;minoN&barbelow;aphthalene (IAN-amines) has been achieved. These potentially bidentate ligands combine the strengths of the beta-diketimine framework with the axial chirality of binaphthyl systems. rac-R-IAN Amines were accessed in 3 linear steps and enantiopure IAN-amine in 4 linear steps. Facile derivatization provided access to a sterically and electronically diverse library of these new reagents. The barrier to atropisomerization was determined for a series of N-substituted IANs, and all members of the series are configurationally stable at room temperature. IAN-Amines are competent ligands for coordination with a variety of metal and Lewis acidic centers and their use in a range of new reactions as organic and organometallic catalysts has been studied. The complexation event to form bis(beta-diketimine) Zr(IV) complexes with rac-R-IAN demonstrated a highly diastereoselective process with a single diastereomer being produced of the 13 potential diastereomeric products. Validation of the IAN-amines as chiral non-racemic catalysts was achieved through their implementation in the enantioselective addition of diethylzinc to aldehydes. The mechanism of asymmetry transfer was investigated for this well-studied reaction. These chiral monodentate pyridine ligands were implemented as Bronsted acid catalysts for the aza-Henry reaction.