Short synthesis of 1,3Z,6Z,9Z-tetraene hydrocarbons. Lepidopteran sex attractants

Abstract

Can. J. Chem. 64. 2427 (1986. A short, convergent synthesis of 1,3Z,6Z,9Z-tetraene hydrocarbons was developed. A key step was the regioselective alkylation of 1,s-dibromo-2-pentyne. The method was used to synthesize tetraenes of chain lengths CI8-C2", to be used in field trials as sex attractants and (or) inhibitors of the winter moth, Operophtera brumata L., and the Bruce spanworm 0 . bruceata H. (Lepidoptera: Geometridae). JOCELYN G. MILLAR et EDWARD W. UNDERHILL. Can. J. Chem. 64, 2427Chem. 64, (1986. On a lnis au point une courte synthbse convergente des hydrocarbures tetraeniques-1,3(Z),6(2),9(2). Une etape clC implique l'alcoylation rCgiosClective du dibromo-1.5 pentyne-2. On a utilisC la methode pour synthetiser des tetraknes comportant de 18 a 20 atomes de carbone; on a utilisk ces hydrocarbures pour determiner leurs proprietes cornrne attractant sexuel et (ou) inhibiteurs des espbces Operophtera brumata L. et 0 . bruceata H. (Lepidoptera; Geometridae).[Traduit par la revue]To date, two 1,3Z96Z,9Z-tetraene hydrocarbons 1 (Scheme 1) have been reported as lepidopteran sex attractants. These are the nonadecatetraene l b , which appears to be the sole component in the sex pheromone of the winter moth, Operophtera brumata L. (Lepidoptera: Geometridae) (1, 2), and the heneicosatetraene I d , which is one of several components in the sex pheromone of Utetheisa ornatrix L. (Lepidoptera: Arctiidae) (3). As these homologous hydrocarbons were found in species from two different families, it is very likely that these compounds or their homologs are sex pheromone components for other lepidopteran species as well (4). As part of our work in screening potential sex attractants, we were interested in obtaining a series of these compounds for field testing. In particular, we wanted the tetraenes l a -c to test as sex attractants and (or) inhibitors for two sympatric species, 0. brumata, mentioned above, and the Bruce spanworm, 0 . bruceata H. Both species are morphologically very similar, and can only be differentiated by dissection. In addition, they both appear to use the nonadecatetraene 1b as a sex attractant (1). One species, 0. brumata, is an economic pest of hardwoods and fruit trees (I), while the other is of lesser economicThe diol was converted to the dibromide 4 (89%) by treatment with carbon tetrabromide and triphenylphosphine (1 1). The diynes 6a-c required for the alkylation step were constructed by cuprous salt-catalyzed reaction of the Grignard reagent of the appropriate terminal alkyne 5 with propargyl bromide (12, 13).Cuprous iodide-catalyzed reaction of the Grignard reagents of the diynes 6 with dibromide 4 (12, 13) selectively gave the desired 1-bromo-3,6,9-alkatriynes 7, contaminated with small amounts (6-12%) of isomeric impurities. The impurities were easily removed by recrystallization of the crude bromotriynes from pentane at 0°C (64-6996). The pure bromotriynes 7 were stereoselectively reduced with dicyclohexylborane to the bromotrienes 8 (59-65%) (14, 15). In our hands, this method of partia...

A sex pheromone component novel to the Geometridae identified from Epirrita autumnata

“…1. The target compound was obtained in an overall yield of 15%, NMR-data and mass spectra of our intermediates (7) and (8) and of the target compound (1) were identical with those reported in the literature (Huang et al, 1983;Millar & Underhill, 1986). Upon oncolumn injection the synthetic compound showed the same mass spectrum and the same gas chromatographic retention time as the natural product.…”

“…Syntheses of this compound have been described earlier (Jain et al, 1983b;Huang et al, 1983;Millar & Underhill, 1986). Our 8-step synthesis, which follows the block principle Cl 1 + C3 + C3 + C4 by employing conventional chain elongations, is outlined in Fig.…”

Synthesis and biological activity of alkynoic acids derivatives against mycobacteria

“…2,5-Alkadiynoic acids 5 (Scheme 1.2) were obtained by coupling of an alkynylmagnesium bromide with propargyl bromide in the presence of cuprous iodide at −10°C in THF (Millar and Underhill, 1986). The condensation reaction occurred in moderate to good yield (63% to 80%).…”

Are Alkyne Reductions Chemo-, Regio-, and Stereoselective Enough To Provide Pure (Z)-Olefins in Polyfunctionalized Bioactive Molecules?

“…159,503,504,508,512,515 Scheme 59 is given as an example. Sometimes the yields are, however, moderate (54%, 509 56%, 515 65% 503 or not reported 508,512 ). Interestingly, although double bonds react with boranes (for instance, Sia 2 BH 218 ), a good chemoselectivity toward alkyne functions could be reached in the presence of alkene(s).…”