Inorganic-Base-Catalysed Synthesis of a,b-Unsaturated Ketones and 3,5 Disubstituted Cyclohex-2-en-1-ones

Both acyclic and cyclic , -unsaturated ketones are important synthetic intermediates for many functional molecules. A simple and efficient strategy for providing either , -unsaturated methyl ketones or 3,5-disubstituted cyclohex-2-en-1-ones as the only product under appropriate reaction conditions was developed. When barium hydroxide was used as the catalyst, the reaction between aldehydes and ketones resulted in the formation of 3,5-disubstituted cyclohex-2-en-1-ones in high yield via a five-step domino reaction. On the other hand, potassium-carbonate-catalysed Claisen-Schmidt reactions between aldehydes and ketones furnished , -unsaturated ketone in high yields.