Unusual base dependent enantioselectivity in a transfer hydrogenation using axially chiral Ir(III)-catalysts

Abstract

New bidentate monosulfonated diamines, with an axially chiral biaryl backbone in combination with different Ir(III) complexes, were investigated in the catalytic transfer hydrogenation of acetophenone under i-PrOH/ i-PrOK conditions. The resulting catalysts showed a strong, unexpected, and unusual base dependent enantioselectivity. Less base than chiral catalyst resulted in an ( R)-configured secondary alcohol, excess of base in the ( S)-enantiomer, using ( P)-configured ligands.