A total synthesis of ([plus-minus])-trans-chrysanthemic acid

The total synthesis of ([plus-minus])-trans-chrysanthemic acid (1) from eucarvone (66) via intermediate [delta][cubed]-4-methylcaren-5-one (68)is discussed. The present synthetic scheme proceeds by ozonolysis of carenone 68 to a key intermediate, keto-acetal 73. Reductive elimination of the enol diethyl phosphate of acetal 73 leads to olefin aldehyde 58 which is ultimately oxidized to ([plus-minus])-trans-chrysanthemic acid.