Thiophosphoramide catalyzed asymmetric Michael addition of cyclopentanone to chalcones

Thiophosphoramide 1b was found to be an effective bifunctional organocatalyst in the asymmetric Michael reaction of cyclopentanone to various chalcones, affording the corresponding adducts in satisfactory yields with moderate to excellent diastereo- (up to 90/10 dr) and enantioselectivities (up to 92% ee).

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2-((S)-3-Oxo-1,3-diphenylpropyl)cyclopentanoneC20H20O2[α]D20=-25.4 (c 1.0, CHCl3)90/10 (anti/syn), 92% ee (anti)Source of chirality: asymmetric organocatalysisAbsolute configuration: (S)

2-((S)-3-Oxo-3-phenyl-1-(4-trifluoromethylphenyl)-propyl)cyclopentanoneC20H19NO4[α]D20=-93.4 (c 1.0, CHCl3)60/40 (anti/syn), 71% ee (anti)Source of chirality: asymmetric organocatalysisAbsolute configuration: (S)

2-((S)-3-Oxo-3-phenyl-1-(4-trifluoromethylphenyl)-propyl)cyclopentanoneC21H19F3O2[α]D20=-23.2 (c 1.1, CHCl3)65/35 (anti/syn), 66% ee (anti)Source of chirality: asymmetric organocatalysisAbsolute configuration: (S)

2-((S)-1-(4-Bromophenyl)-3-oxo-3-phenylpropyl)cyclopentanoneC20H19BrO2[α]D20=-27.4 (c 1.0, CHCl3)71/29 (anti/syn), 61% ee (anti)Source of chirality: asymmetric organocatalysisAbsolute configuration: (S)

2-((S)-1-(4-Methylphenyl)-3-oxo-3-phenylpropyl)-cyclopentanoneC21H22O2[α]D20=-39.2 (c 1.0, CHCl3)90/10 (anti/syn), 62% ee (anti)Source of chirality: asymmetric organocatalysisAbsolute configuration: (S)

2-((S)-1-(4-Methoxyphenyl)-3-oxo-3-phenylpropyl)-cyclopentanoneC21H22O3[α]D20=-30.2 (c 1.0, CHCl3)85/15 (anti/syn), 65% ee (anti)Source of chirality: asymmetric organocatalysisAbsolute configuration: (S)

2-((S)-3-(4-Bromophenyl)-3-oxo-1-phenylpropyl)-cyclopentanoneC20H19BrO2[α]D20=-21.6 (c 1.0, CHCl3)80/20 (anti/syn), 59% ee (anti)Source of chirality: asymmetric organocatalysisAbsolute configuration: (S)

2-((S)-1-(2-Methoxyphenyl)-3-(4-nitrophenyl)-3-oxopropyl)cyclopentanoneC21H21NO5[α]D20=-16.8 (c 0.70, CHCl3)60/40 (anti/syn), 64% ee (anti)Source of chirality: asymmetric organocatalysisAbsolute configuration: (S)

2-((S)-1-(4-Methoxyphenyl)-3-(4-nitrophenyl)-3-oxopropyl)cyclopentanoneC21H21NO5[α]D20=-10.0 (c 1.0, CHCl3)64/36 (anti/syn), 60% ee (anti)Source of chirality: asymmetric organocatalysisAbsolute configuration: (S)

2-((S)-1-(4-Methoxyphenyl)-3-(4-nitrophenyl)-3-oxopropyl)cyclopentanoneC21H22O2[α]D20=-15.3 (c 0.30, CHCl3)72/28 (anti/syn), 57% ee (anti)Source of chirality: asymmetric organocatalysisAbsolute configuration: (S)