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The synthesis of β-damascone (Ⅰ), an odoriferous natural product, was investigated from 2,2,6-trimethylcyclohexanone (Ⅱ); (Ⅱ) was ethynylated by the action of monoacetylide anion prepared from acetylene and sec-butyllithium at -78℃, to give an ethynylcarbinol(Ⅲ), which was isomerized to an acetylcyclohexene(Ⅳ) by refluxing in aqueous oxalic or formic acid. (Ⅳ) was treated with sec-butyllithium, the enolate was reacted with freshly dried acetaldehyde, and the resultant β-hydroxyketone (Ⅴ) was dehydrated by TsOH to β-damascone, trans-2,6,6-trimethyl-1-crotonyl-1-cyclohexene(Ⅰ).
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