Chiral phosphine-prolineamide as an organocatalyst in direct asymmetric aldol reactions

Chiral phosphine-prolineamide 1a was employed as an organocatalyst in direct asymmetric aldol reactions of various aromatic aldehydes with ketones. Cyclohexanone led to the aldol products in up to 98% ee and with good diastereoselectivity using 10 mol % of TFA and 30 mol % of prolineamide 1a in DMF at 0 °C.

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(S)-N-(2-Diphenylphosphinophenyl)pyrrolidine-2-carboxamideC23H23N2OP[α]D25=-39.3 (c 0.30, CHCl3)Source of chirality: l-(−)-prolineAbsolute configuration: (S)

(S)-N-(2-Diphenylphosphorylphenyl)pyrrolidine-2-carboxamideC23H23N2O2P[α]D25=+36.8 (c 0.30, CHCl3)Source of chirality: l-(−)-prolineAbsolute configuration: (S)