Fatty acids,part 21: ring opening reactions of synthetic and natural furanoid fatty esters

Methyl 2,5-disubstituted C₁₈ furanoid fatty ester (viz. methyl 9,12-epoxyoctadeca-9,11-dienoate) was readily converted to methyl 9,12-dioxostearate using mineral or maleic acid. Conversion of the naturally occurring 2,3,5-trisubstituted furanoid fatty ester (viz. methyl 10,13-epoxy-11-methyloctadeca-10,12-dienoate) to the corresponding methyl 10,13-dioxo-11-methylstearate was much slower in rate under similar reaction conditions. The case of separating the dioxo derivatives from a mixture of other common fatty esters was demonstrated and the cyclodehydration of the isolated dioxo derivatives to the parent furanoid ester was rapidly achieved using dilute BF₃-methanol complex.