Highly enantioselective Rh-catalyzed transfer hydrogenation of N-sulfonyl ketimines

Several imine species comprising N-sulfinyl and N-sulfonyl ketimine, oxime, and enamine derivatives were subjected to asymmetric transfer hydrogenation in an azeotropic mixture of formic acid/triethylamine. Among them, the Rh-catalyzed transfer hydrogenation of N-sulfonyl ketimine afforded the corresponding 1-arylalkylamines in excellent yield and with high enantioselectivity.

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(S)-1-Phenyl-N-tosylethanamineC15H17NO2SEe 96%[α]D20=-64.5 (c 0.65, CHCl3)Source of chirality: asymmetric transfer hydrogenationAbsolute configuration: (S)

(S)-1-Phenyl-N-nosylethanamineC14H14N2O4SEe 96%[α]D20=-18.7 (c 0.54, CHCl3)Source of chirality: asymmetric transfer hydrogenationAbsolute configuration: (S)

(S)-1-Phenyl-N-(t-butanesulfonyl)ethanamineC12H19NO2SEe 94%[α]D20=-34.9 (c 0.51, CHCl3)Source of chirality: asymmetric transfer hydrogenationAbsolute configuration: (S)

(S)-1-(3-Methoxyphenyl)-N-tosylethanamineC16H19NO3SEe 99%[α]D20=-59.8 (c 1.28, CHCl3)Source of chirality: asymmetric transfer hydrogenationAbsolute configuration: (S)

(S)-1-(4-Methoxyphenyl)-N-tosylethanamineC16H19NO3SEe 97%[α]D20=-77.3 (c 0.59, CHCl3)Source of chirality: asymmetric transfer hydrogenationAbsolute configuration: (S)

(S)-1-(3-Chlorophenyl)-N-tosylethanamineC15H16ClNO2SEe 98%[α]D20=-70.5 (c 0.68, CHCl3)Source of chirality: asymmetric transfer hydrogenationAbsolute configuration: (S)

(S)-1-(4-Chlorophenyl)-N-tosylethanamineC15H16ClNO2SEe 99%[α]D20=-70.0 (c 0.34, CHCl3)Source of chirality: asymmetric transfer hydrogenationAbsolute configuration: (S)

(S)-1-(4-Trifluoromethylphenyl)-N-tosylethanamineC16H16F3NO2SEe 96%[α]D20=-48.1 (c 0.58, CHCl3)Source of chirality: asymmetric transfer hydrogenationAbsolute configuration: (S)

(S)-1-(2-Naphthyl)-N-tosylethanamineC19H19NO2SEe 96%[α]D20=-72.0 (c 0.5, CHCl3)Source of chirality: asymmetric transfer hydrogenationAbsolute configuration: (S)

(S)-1-Phenyl-N-tosylpropanamineC16H19NO2SEe 95%[α]D20=-52.4 (c 0.72, CHCl3)Source of chirality: asymmetric transfer hydrogenationAbsolute configuration: (S)

(S)-1-(2-Furyl)-N-tosylethanamineC13H15NO3SEe 90%[α]D20=-79.6 (c 0.55, CHCl3)Source of chirality: asymmetric transfer hydrogenationAbsolute configuration: (S)

(S)-1-(2-Benzofuryl)-N-tosylethanamineC17H17NO3SEe 83%[α]D20=-113.1 (c 0.52, CHCl3)Source of chirality: asymmetric transfer hydrogenationAbsolute configuration: (S)

(S)-1-(2-Thienyl)-N-tosylethanamineC13H15NO2S2Ee 97%[α]D20=-68.6 (c 0.61, CHCl3)Source of chirality: asymmetric transfer hydrogenationAbsolute configuration: (S)

(S)-1-(2-Benzothienyl)-N-tosylethanamineC17H17NO2S2Ee 97%[α]D20=-103.5 (c 0.72, CHCl3)Source of chirality: asymmetric transfer hydrogenationAbsolute configuration: (S)

(S)-1-Cyclopropyl-N-tosylethanamineC12H17NO2SEe 67%[α]D20=+7.5 (c 0.99, CHCl3)Source of chirality: asymmetric transfer hydrogenationAbsolute configuration: (S)