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 ...
