Synthetic Study of (+)-Nootkatone from (-)-β-Pinene

Article abstract of DOI:10.1021/jo01292a010

A facile stereoselective synthesis of (+)-nootkatone (1) has been achieved starting with (+)-nopinone (2b).The key step was the conjugate addition of methallyltrimethylsilane (20b) to trans-3-ethylidenenopinone (16), which was obtainable from 2b on the cross condensation with acetaldehyde followed by acid treatment, giving an adduct with the desired stereochemistry, 24a, as the predominant product.Dione 23, obtained from the adduct on methylation followed by ozonization, afforded nootkatone hydrochloride (26) on treatment with hydrogen chloride.Regioselective dehydrochlorination of the hydrochloride yielded 1.An alternative route in which allyltrimethylsilane was used is also described.