The rearrangement of fatty cyclopropenoids in the presence of boron trifluoride

The destruction of the cyclopropenoid ring system of methyl 9,10 methyleneoctadec-9-enoate (methyl sterculate) with boron trifluoride etherate has been shown to give a complex mixture of products, including methyl esters of C₁₉ allenes (12%), a C₁₈ alkyne (11%) and a variety of C₁₉ and C₂₀ conjugated dienes containing either a methyl or methylene branch. The methylene group lost from the methyl sterculate reactant in the formation of methyl octadec-9-ynoate is incorporated into a second molecule of reactant to yield a mixture of methyl 9-methylene-trans-nonadec-10-enoate and the 11-methylene-trans-9-isomer.