The Mannich reaction Mechanism O H COH R-C-C-CHO-NR H R-C-CH,=CH R a B-aminoketone an enole R a Mannich base +H HM以、82H2QHc=NR an iminium ion14 The Mannich Reaction: Mechanism H C H O HNR'' 2 NR'' 2 C H 2 HO H + + H + -H 2 O H 2 C NR 2 '' R' C OH CH R C O R CH 2R' H + H + an enole an iminium ion a β-aminoketone R' C O C H R CH 2 N R 2 '' a Mannich base