Chemoselective and enantioselective transfer hydrogenation of β,β-disubstituted nitroalkenes catalyzed by a water-insoluble chiral diamine–rhodium complex in water

Asymmetric transfer hydrogenation of β,β-disubstituted nitroalkenes catalyzed by a chiral diamine–rhodium complex in combination with HCO2Na–HCO2H as a hydrogen source in water was successfully realized with high reactivity, excellent chemoselectivity and good enantioselectivity. The metal precursor and pH value of the aqueous solution have a large influence on the reactivity and chemoselectivity. The substituents on the benzene rings and the sulfonyl groups of TsDPEN have significant effects on the enantioselectivity. This catalytic asymmetric transformation is one of the most practical pathways to obtain optically active nitroalkanes.

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(1R,2R)-N-(p-Toluenesulfonyl)-1,2-bis(3-nitrophenyl)-1,2-ethylenediamineC21H20N4O6S[α]D28=+32.9 (c 0.98, MeOH)Source of chirality: (1R,2R)-1,2-bis(3-nitrophenyl)-1,2-ethylenediamineAbsolute configuration: (R,R)

(1R,2R)-N-(3,5-Ditrifluoromethylbenzylsulfonyl)-1,2-bis(3-nitrophenyl)-1,2-ethylenediamineC22H16F6N4O6S[α]D20=+66.8 (c 0.5, MeOH)Source of chirality: (1R,2R)-1,2-bis(3-nitrophenyl)-1,2-ethylenediamineAbsolute configuration: (R,R)

(1R,2R)-N-(3,5-Ditrifluoromethylbenzylsulfonyl)-1,2-bis(2-nitrophenyl)-1,2-ethylenediamineC22H16F6N4O6S[α]D20=-77.1 (c 0.5, MeOH)Source of chirality: (1R,2R)-1,2-bis(2-nitrophenyl)-1,2-ethylenediamineAbsolute configuration: (R,R)

(1R,2R)-N-(3,5-Ditrifluoromethylbenzylsulfonyl)-1,2-bis(4-nitrophenyl)-1,2-ethylenediamineC22H16F6N4O6S[α]D20=+5.2 (c 0.5, MeOH)Source of chirality: (1R,2R)-1,2-bis(4-nitrophenyl)-1,2-ethylenediamineAbsolute configuration: (R,R)

(1R,2R)-N-(3,5-Ditrifluoromethylbenzylsulfonyl)-1,2-bis(4-methoxyphenyl)-1,2-ethylenediamineC24H22F6N2O4S[α]D20=+129.2 (c 0.5, MeOH)Source of chirality: (1R,2R)-1,2-bis(4-methoxyphenyl)-1,2-ethylenediamineAbsolute configuration: (R,R)

(1R,2R)-N-Trifluoromethanesulfonyl-1,2-bis(3-nitrophenyl)-1,2-ethylenediamineC15H13F3N4O6S[α]D20=+60.7 (c 0.5, MeOH)Source of chirality: (1R,2R)-1,2-bis(3-nitrophenyl)-1,2-ethylenediamineAbsolute configuration: (R,R)

(S)-1,2-Dimethoxy-4-(1-nitropropan-2-yl)benzeneC11H15NO4Ee = 86%[α]D20=-52.0 (c 0.60, CHCl3)Source of chirality: asymmetric transfer hydrogenationAbsolute configuration: (S)