Synthesis of sesquiterpenoids related to nootkatone—structure determination by NMR using tris(dipivalomethanato)europium

✍ Scribed by T.J. Leitereg

• Book ID: 104236810
• Publisher: Elsevier Science
• Year: 1972
• Tongue: French
• Weight: 142 KB
• Volume: 13
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)84889-9

✦ Synopsis

The total synthesis of racemic nootkatone (L), a sesquiterpenoid whose (+)-antipode is found in grapefruit', has been reported independently by Schudel' and Marshal13.

The following describes a synthesis leading to a series of compounds related to 1. (+)-Dihydrocarvone4 (2) was prepared from (-)-carvone by reduction' or from (+)-limonene by oxidation6. The anion of (+)-2 (method of McQuillin7) was condensed with trans-3-penten-*-one. Dehydration with potassium tert-butoxide in DMSO afforded a mixture of enonea and startinn material.

Unchanged (+)-2 (47% by weight) was removed by distillation and a mixture of products was obtained, bp 85-115" (3pHg); spectral data indicated that these products were isomers having the general structure drawn above.