An Efficient Synthesis of Methyl (±)-Jasmonate and (Z)-Jasmone

An efficient synthesis of methyl (±)-jasmonate and (Z)-jasmone is described. The Key step is a phase-transfer reaction between cyclopentane ( 9 ) and 1, 4-dibromo-2-pentene ( 6a/b ) to give the spiro [2.4]hepten-4-ones 4a and 4b .