Pyrrolidine–oxyimide catalyzed asymmetric Michael addition of α,α-disubstituted aldehydes to nitroolefins

Organocatalytic enantioselective Michael addition of α,α-disubstituted aldehydes onto nitroolefins using pyrrolidine–oxyimide catalyst was reported. The reaction works effectively under neat conditions with 15 mol % of catalyst and 10 mol % of p-nitrobenzoic acid as an additive at 0 °C; this results in the formation of Michael adducts possessing an all-carbon quaternary center with good yields and enantioselectivities.

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(R)-2,2-Dimethyl-4-nitro-3-(4-nitrophenyl)butanalC12H14N2O5[α]D25 = +9.8 (c 1, CHCl3)Source of chirality: Asymmetric synthesisAbsolute configuration: (R)

(R)-2,2-Dimethyl-4-nitro-3-phenylbutanalC12H15NO3[α]D25 = +6.9 (c 0.9, CHCl3)Source of chirality: Asymmetric synthesisAbsolute configuration: (R)

(R)-3-(4-Chlorophenyl)-2,2-dimethyl-4-nitrobutanalC12H14ClNO3[α]D25 = +4.1 (c 1.5, CHCl3)Source of chirality: Asymmetric synthesisAbsolute configuration: (R)

(R)-3-(4-Methoxyphenyl)-2,2-dimethyl-4-nitrobutanalC13H17NO4[α]D25 = −3.1 (c 1, CHCl3)Source of chirality: Asymmetric synthesisAbsolute configuration: (R)