Submitted to: Fruit Flies of Economic Importance International Symposium
Publication Type: Abstract Only
Publication Acceptance Date: May 6, 2002
Publication Date: N/A
Interpretive Summary: The Mediterranean fruit fly, Ceratitis capitata(Wiedemann),commonly known as the medfly, is a serious pest of over 253 varieties of fruits and vegetables. For more than 30 years, the major operational programs by federal and state agencies have deployed annually over 50,000 detection traps baited with the male medfly attractant, trimedlure. Scientists at BARC have developed a practical synthesis of ceralure B1, a superior attractant for the Mediterranean fruit fly, much exceeding the attractiveness of standard trimedlure. The new method, based on a commercially available starting material, nearly doubled the yield of an existing synthesis. It produces ceralure B1 without using chromatographic purifications and is amenable for scale-up.
Technical Abstract: Ethyl cis-5-iodo-trans-2-methyl-1-cyclcohexane-1-carboxylate (Ceralure B1) is a potent attractant for the Mediterranean fruit fly, Ceratitis capitata (Wiedemann). Scientists at BARC developed a new synthesis of Ceralure B1 that provided better yields than the existing methods. The new approach seems suitable for scale-up and commercialization. The synthesis starts with the commercially available trans-6-methyl-3-cyclohexane-1-carboxylic acid (Siglure acid), which was converted in two steps to trans-2-methyl-6-oxabicyclo[3.2.1]octan-7-one. Ring opening of the later with trichloromethylsilane provided a mixture of cis-5-iodo-trans-2-methyl-1-cyclcohexane-1-carboxylic acid and trans-5-iodo-trans-2-methyl-1-cyclcohexane-1-carboxylic acid. In the key step, the undesired trans, trans - acid was converted back to the precursor rlactone and recycled. Ongoing field studies have revealed that racemic Ceralure B1 exceeded the attractiveness of standard trimedlure by two to three times, whereas optically active (-)-Ceralure B1 was only ~ 30% more active than the racemate.