Oxygen–chlorine interactions in the transition state of asymmetric Michael additions of carbonyl compounds to β-nitrostyrene

An oxygen–chlorine interaction is reported in the transition state of the Michael addition of acetone to nitrostyrene catalyzed by enantioenriched monosulfonamides. The interaction between the oxygen from the nitro group and the chlorine at the ortho-position of the sulfonamide moiety is supported by theoretical calculations. Asymmetric Michael addition products catalyzed by monosulfonamides were obtained in moderate yields and enantioselectivities.

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N-((1R,2R)-2-Aminocyclohexyl)-2,3-dichlorobenzenesulfonamideC12H16Cl2N2O2S[α]D20 = −20 (c 0.72, CH2Cl2)Absolute configuration: (1R,2R)Source of chirality: (R,R)-1,2-diaminocyclohexane

N-((1R,2R)-2-Aminocyclohexyl)-2,5-dichlorobenzenesulfonamideC12H16Cl2N2O2S[α]D20 = −29 (c 1.1, MeOH)Absolute configuration: (1R,2R)Source of chirality: (R,R)-1,2-diaminocyclohexane

N-((1R,2R)-2-Aminocyclohexyl)-2,6-dichlorobenzenesulfonamideC12H16Cl2N2O2S[α]D20 = −30 (c 0.84, CH2Cl2)Absolute configuration: (1R,2R)Source of chirality: (R,R)-1,2-diaminocyclohexane

N-((1R,2R)-2-aminocyclohexyl)-2,5-dibromobenzenesulfonamideC12H16Br2N2O2S[α]D20 = −17 (c 6.1, MeOH)Absolute configuration: (1R,2R)Source of chirality: (R,R)-1,2-diaminocyclohexane