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

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.

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