Applications of N′-alkylated derivatives of TsDPEN in the asymmetric transfer hydrogenation of CO and CN bonds

Arene/Ru(II) complexes of (R,R)-N-alkyl-TsDPEN ligands are effective in the asymmetric transfer hydrogenation of ketones and imines in formic acid/triethylamine solution. The complex derived from the N′-Bn derivative of TsDPEN reduces monocyclic imines in up to 60% ee, whilst the N′-Me derivative of TsDPEN forms a more active catalyst than the non-alkylated analogue and reduces ketones in up to 97% ee.

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N′-(3,5-Dimethylbenzyl)-N-tosyl-1,2-diphenylethane-1,2-diamineC30H32N2O2SEe = 100%[α]D35=-36.4 (c 0.48, CHCl3)Source of chirality: enantiomerically pure starting material, (R,R)-TsDPENAbsolute configuration: (R,R)

N′-(2,4,6-Trimethylbenzyl)-N-tosyl-1,2-diphenylethane-1,2-diamineC31H34N2O2SEe = 100%[α]D23=-26.4 (c 0.36, CHCl3)Source of chirality: enantiomerically pure starting material, (R,R)-TsDPENAbsolute configuration: (R,R)

N′-(2,4,6-Trimethylbenzyl)-N-tosyl-1,2-diphenylethane-1,2-diamineC30H32N2O4SEe = 100%[α]D23=-39.1 (c 0.42, CHCl3)Source of chirality: enantiomerically pure starting material, (R,R)-TsDPENAbsolute configuration: (R,R)

N′-(4-Methylbenzyl)-N-tosyl-1,2-diphenylethane-1,2-diamineC20H30N2O2SEe = 100%[α]D32=-42.7 (c 0.5, CHCl3)Source of chirality: enantiomerically pure starting material, (R,R)-TsDPENAbsolute configuration: (R,R)

N′-(3-Methylbenzyl)-N-tosyl-1,2-diphenylethane-1,2-diamineC20H30N2O2SEe = 100%[α]D32=-35 (c 0.6, CHCl3)Source of chirality: enantiomerically pure starting material, (R,R)-TsDPENAbsolute configuration: (R,R)

Complex 24C36H37ClN2O2SRuEe = 100%[α]D31=-200.9 (c 0.007, CHCl3)Source of chirality: enantiomerically pure (R,R)-TsDPENAbsolute configuration: (R,R)

Complex 25C37H39ClN2O2SRuEe = 100%[α]D30=+116 (c 0.01, CHCl3)Source of chirality: enantiomerically pure (R,R)-TsDPENAbsolute configuration: (R,R)

Complex 26C36H37ClN2O4SRuEe = 100%[α]D31=-211.8 (c 0.005, CHCl3)Source of chirality: enantiomerically pure (R,R)-TsDPENAbsolute configuration: (R,R)

Complex 27C35H35ClN2O2SRuEe = 100%[α]D29=-266.6 (c 0.01, CHCl3)Source of chirality: enantiomerically pure (R,R)-TsDPENAbsolute configuration: (R,R)

Complex 28C37H39ClN2O2SRuEe = 100%[α]D31=-276.5 (c 0.009, CHCl3)Source of chirality: enantiomerically pure (R,R)-TsDPENAbsolute configuration: (R,R)

Complex 18C36H37ClN2O2SRuEe = 100%[α]D21=-208 (c 0.0036, CHCl3)Source of chirality: enantiomerically pure (R,R)-TsDPENAbsolute configuration: (R,R)

Complex 15C36H37ClN2O2SRuEe = 100%[α]D25=-404 (c 0.0023, CHCl3)Source of chirality: enantiomerically pure (R,R)-TsDPENAbsolute configuration: (R,R)

1-Ethyl-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinolineC13H19NO2Ee = 89%[α]D26=-50.3 (c 0.1, CH2Cl2)Source of chirality: asymmetric reduction of dihydroisoquinolineAbsolute configuration: (S)

1-Benzyl-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinolineC18H21NO2Ee = 89%[α]D30=-8.3 (c 0.1, acetone)Source of chirality: asymmetric reduction of dihydroisoquinolineAbsolute configuration: (S)

2-Phenyl-piperidineC11H15NEe = 60%[α]D25=+14.7 (c 0.08, CH2Cl2)Source of chirality: asymmetric reduction of imineAbsolute configuration: (R)

2-(4-Methoxyphenyl)-piperidineC12H17NOEe = 57%[α]D31=+11.7 (c 0.32, CH3OH)Source of chirality: asymmetric reduction of imineAbsolute configuration: (R)

2-(4-Methylphenyl)-piperidineC12H17NEe = 61%[α]D31=+36.7 (c 0.4, CHCl3)Source of chirality: asymmetric reduction of imineAbsolute configuration: (R)

2-(4-Trifluoromethylphenyl)-piperidineC12H14F3NEe = 50%[α]D33=+14.4 (c 0.17, CHCl3)Source of chirality: asymmetric reduction of imineAbsolute configuration: (R)