Process comprising the use of new iridium catalysts for enantioselective hydrogenation of 4-substituted 1,2-dihydroquinolines

A process for preparing a compound of formula (Ia) or (Ib),

• wherein
• R1 is selected from the group consisting of C1-C6-alkyl, C1-C6-haloalkyl, C1-C6-alkoxy-C1-C6-alkyl, C3-C6-cycloalkyl, C6-C14-aryl, or C6-C14-aryl-C1-C4-alkyl,
• wherein the C1-C6-alkyl, C3-C6-cycloalkyl and the C1-C6-alkoxy in the C1-C6-alkoxy-C1-C6-alkyl moiety, are optionally substituted by 1 to 3 substituents independently selected from the group consisting of halogen, C1-C4-alkoxy, C1-C4-haloalkyl, C1-C4-haloalkoxy and phenyl, wherein the phenyl may be substituted by one to five substituents selected independently from each other from halogen, C1-C4-alkyl, C1-C4-alkoxy, C1-C4-haloalkyl, and C1-C4-haloalkoxy, and
• wherein the C6-C14-aryl and the C6-C14-aryl in the C6-C14-aryl-C1-C4-alkyl moiety in each case is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy and C1-C4-haloalkoxy,
• R2 and R3 are the same and are selected from the group consisting of hydrogen, C1-C6-alkyl, C1-C6-haloalkyl and C1-C6-alkoxy-C1-C6-alkyl,
• or
• R2 and R3 together with the carbon which they are bound to, form a C3-C6-cycloalkyl ring,
• R4 is hydrogen, C1-C6-alkyl, C1-C6-haloalkyl, C1-C6-alkoxy, C1-C6-haloalkoxy, C1-C6-alkylamino, C2-C6-alkenyl, C2-C6-alkynyl, C3-C6-cycloalkyl, C3-C6-cycloalkyl-C1-C4-alkyl, C2-C6-alkenyloxy, 9-flurorenylmethyleneoxy, C6-C14-aryl, C6-C14-aryloxy, C6-C14-aryl-C1-C4-alkyloxy or C6-C14-aryl-C1-C4-alkyl,
• wherein the C6-C14-aryl as such or as part of a composite substituent is unsubstituted or substituted by one to five substituents selected from the group consisting of halogen, C1-C4-alkyl, C1-C4-haloalkyl, C1-C4-alkoxy and C1-C4-haloalkoxy,
• n is 0, 1, 2, 3 or 4,
• each substituent R5, if present, is independently selected from the group consisting of halogen, C1-C6-alkyl, C1-C6-haloalkyl, C1-C6-alkoxy, hydroxyl, amino and —C(═O)—C1-C6-alkyl,
• the process comprising enantioselective hydrogenation of a compound of formula (II)
• wherein the substituents R1, R2, R3, R4, R5 and the integer n are each as defined for the compound of formula (Ia) or (Ib),
• in presence of a chiral iridium catalyst,
• wherein the chiral iridium catalyst is of the general formula (Va) or (Vb)
• wherein
• R6 is 2,6-diethyl-4-methylphenyl,
• R7 is hydrogen,
• R8 is methyl,
• R9 and R10 are both cyclohexyl,
• Y is a non-coordinating anion selected from the group consisting of [B(R18)4]− and [Al{OC(CF3)3}4]−of formula (VII),
• wherein R18 is 3,5-bis(trifluoromethyl)phenyl.