A novel and efficient direct aldol condensation from ketones and aromatic aldehydes catalyzed by proline–TEA through a new pathway

A novel and efficient direct aldol condensation from various ketones and a wide range of aldehydes was catalyzed by l-proline–TEA (triethylamine) in MeOH at room temperature, affording the corresponding (E)-α,β-unsaturated ketones in excellent yields. By using the method, some complicated (E)-α,β-unsaturated ketone C-glycosides were obtained from unmodified ketone C-glycosides and aldehydes. This reaction proceeds through a new pathway, in which the specific intermediate was captured and identified.