Two synthetic routes from farnesol to (±)-sesquicarene (1) involving intramolecular carbenoid cycliziation of acyclic precursors as the key step are described. The diazoketone (4) derived from 2, 6, 10-trimethylundeca-5, 9-dienoicacid (14) undergoes efficient copper- catalyzed cyclization to sesquicarone (5). Sesquicarene is obtained by pyrolysis of the sodium salt of the p-toluenesulfonylhydrazone of 5. A direct cyclization of farnesal p- ...
