Organocatalytic asymmetric aza-Michael addition of pyrazole to chalcone

An efficient enantioselective aza-Michael addition of pyrazole to chalcone was established. In the presence of the primary amine derived from cinchona alkaloid and acidic additive, the reactions afforded 1,4-adducts in high yields (up to 98%) with 68–88% ee.

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1,3-Diphenyl-3-(1H-pyrazol-1-yl)propan-1-oneC18H16N2O[α]D20=+64.3 (c 1.00, CHCl3) 76% eeAbsolute configuration: not known

1-Phenyl-3-(1H-pyrazol-1-yl)-3-p-tolylpropan-1-oneC19H18N2O[α]D20=+34.2 (c 1.00, CHCl3) 68% eeAbsolute configuration: not known

3-(3-Bromophenyl)-1-phenyl-3-(1H-pyrazol-1-yl)propan-1-oneC18H15N2OBr[α]D20=+56.9 (c 1.00, CHCl3) 82% eeAbsolute configuration: not known

1-(3-Methoxyphenyl)-3-phenyl-3-(1H-pyrazol-1-yl)propan-1-oneC19H18N2O2[α]D20=+66.5 (c 1.00 CHCl3) 77% eeAbsolute configuration: not known

3-(4-Fluorophenyl)-1-phenyl-3-(1H-pyrazol-1-yl)propan-1-oneC18H15N2OF[α]D20=+58.2 (c 1.00, CHCl3) 72% eeAbsolute configuration: not known

3-(4-(Trifluoromethyl)phenyl)-1-phenyl-3-(1H-pyrazol-1-yl)propan-1-oneC19H15N2OF3[α]D20=+60.2 (c 1.00, CHCl3) 84% eeAbsolute configuration: not known

3-(4-Bromophenyl)-1-phenyl-3-(1H-pyrazol-1-yl)propan-1-oneC18H15N2OBr[α]D20=+36.0 (c 1.00, CHCl3) 83% eeAbsolute configuration: not known

3-(3-Nitrophenyl)-1-phenyl-3-(1H-pyrazol-1-yl)propan-1-oneC18H15N3O3[α]D20=+27.9 (c 0.80, CHCl3) 80% eeAbsolute configuration: not known

3-(4-Bromophenyl)-1-(3-chlorophenyl)-3-(1H-pyrazol-1-yl)propan-1-oneC18H14N2OClBr[α]D20=+27.8 (c 1.00, CHCl3) 76% eeAbsolute configuration: not known

1-(4-Methoxyphenyl)-3-(1H-pyrazol-1-yl)-3-p-tolylpropan-1-oneC20H20N2O2[α]D20=+32.1 (c 1.00, CHCl3) 83% eeAbsolute configuration: not known

3-(4-Methoxyphenyl)-1-phenyl-3-(1H-pyrazol-1-yl)propan-1-oneC19H18N2O2[α]D20=+12.5 (c 1.00, CHCl3) 30% eeAbsolute configuration: not known

1-(3-Chlorophenyl)-3-phenyl-3-(1H-pyrazol-1-yl)propan-1-oneC18H15N2OCl[α]D20=+49.0 (c 1.00, CHCl3) 66% eeAbsolute configuration: not known

3-(3,5-Dimethyl-1H-pyrazol-1-yl)-1,3-diphenylpropan-1-oneC20H20N2O[α]D20=+124.4 (c 1.00, CHCl3) 72% eeAbsolute configuration: not known