Yields of Suzuki couplings involving indoles depended upon (i) whether arylboronic acids or arylpinacolboronate esters were used, (ii) whether the heterocycle was the aryl halide or the arylboron coupling partner, and (iii) whether the heterocycle was protected or not. Highest yields, which were unaffected by incorporating Boc or Tos protection at the heterocyclic nitrogen, were obtained when indole bromides were reacted with phenylboronic acids. When indolylboronic acids were reacted with phenyl bromides, yields were somewhat lower and depended on the nitrogen substituent, being highest in the absence of protection, lower in the presence of the Boc group, and lowest of all with the Tos group. Arylpinacolboronate esters were less reactive than arylboronic acids. They required considerably longer reaction times and furnished generally lower yields of biaryl. Furthermore, irrespective of whether the heterocycle was the aryl bromide or the arylpinacolboronate ester, these yields were highest when it was protected with the Tos group. Yields were lower with the Boc group, and unprotected heterocycles gave only traces of biaryl. Careful selection of arylboron reagent, of coupling partner roles, and of protecting groups are essential to ensuring optimum results in these Suzuki couplings. These results may also be relevant to couplings involving other substrates.

Large-scale field experiments on the Mediterranean corn borer, Sesamia nonagrioides Lefèbvre (Lepidoptera: Noctuidae), were carried out in 2004 -2006 on maize [ Zea mays L. (Poaceae)] fields using ( Z )-11-hexadecenyl trifluoromethyl ketone, an antagonist analog of the pheromone of this species, to evaluate a possible reduction of damage caused by this pest. The effect of the treatments on the European corn borer, Ostrinia nubilalis Hübner (Lepidoptera: Crambidae), a sympatric species, was also determined. Evaluation of the success of the experiments was assessed by counting (i) the number of males caught by pheromone traps in treated and untreated fields, (ii) the number of plants attacked by both insects in both plots, and (iii) the number of larvae present in infested plants in both fields. Effectiveness of the treatment was high for the second generation of the Mediterranean corn borer, the most harmful to the crop (86 -90% reduction in the number of plants attacked and 67 -98% reduction in the number of larvae per plant in treated fields in comparison to untreated fields), and moderate for the third generation (reduction of 41-71% and 33 -77%, respectively). Treatments were also effective for the second generation of the European corn borer (61 -75% reduction in the number of plants attacked, 58 -78% reduction in the number of larvae found per plant) as well as for the third generation (69 -97% and 70 -98% reduction, respectively). By plotting the amount of the antagonist remaining on the dispensers after 40 -45 days of exposure with time, the mean release rate of the compound was calculated to be 2.2%/day in 2004, 1.95%/day in 2005, and 2.1%/day in 2006, with 26% of the initial compound remaining after 20 days of experimentation. The emission rate appears to cover the flight of the most damaging second generation of both insects. Prospects of using trifluoromethyl ketones as new potential agents for pest control are also outlined.

The differing antagonist activity of (Z)-13-hexadecen-2-one (Z11 -14 : MK, 1) and its 1,1,1-trifluoro derivative (Z11 -14 : TFMK, 2), two closely related analogues of the European corn borer pheromone Ostrinia nubilalis (Z strain), and their rationale is reported. Both chemicals exhibited some electrophysiological activity, and topical application of 10 pg of pheromone analogue on male antennae was sufficient to induce significantly lower depolarization responses to the pheromone versus untreated insects. In a wind tunnel, the number of European corn borer males attracted to sources containing mixtures of 1 + pheromone in ratios ! 1 : 1 was significantly lower than the number attracted to a source containing pheromone alone. Source contact behaviour was dramatically impaired when the 1 + pheromone blend reached a ratio of 10 : 1, in which only 2 % of males displayed source contact in the presence of antagonist. When compound 1 was present at the source, males usually flew upwind with occasional downwind reversals; when compound 2 was present at the lure, males performed wider crosswind reversals, with little progress toward the source. In the field, traps baited with mixtures of both compounds with the pheromone in ratios of 5 : 1 and 10 : 1 elicited a significantly decreased number of male catches. In esterase inhibition assays, compound 2 was a potent inhibitor (IC 50 = 70 nM), whereas the nonfluorinated compound 1 was not. The different activity of both compounds is presumed to be due to different mechanisms of action; considerations for using methyl ketone analogues as new behavioural antagonists of the pheromone are outlined.

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