Reversal of stereochemistry by adding Ti(OiPr)4 in the enantioselective phenylacetylene addition to aldehydes using l-prolinol-backbone ligand

The readily synthesized chiral ligand 1 in combination with Ti(OiPr)4 provided the products with opposite absolute configuration in significant enantiomeric excesses and high yields. The ratio of Ti(OiPr)4 to the ligand had great influence on the enantiomeric excess of the product.