Asymmetric Hydrogenation of Isoquinolinium Salts Catalyzed by Chiral Iridium Complexes: Direct Synthesis for Optically Active 1,2,3,4‐Tetrahydroisoquinolines

The salt makes the difference: In the presence of a chiral iridium catalyst, 1- and 3-substituted as well as 1,3-disubstituted isoquinolinium salts can be hydrogenated, giving the corresponding 1,2,3,4-tetrahydroisoquinolines in high enantiomeric excess after a basic workup (see scheme). This protocol is applicable to the synthesis of the prescription drug solifenacin.