Ant alarm pheromone

Example Optically active acid (16) was needed (p T 107 ) for the synthesis of an ant alarm pheromone. The branch point ( in 16) is also the chiral centre so it is better to avoid disconnections there. The 1,2 C-C disconnection (16a) is ideal as it gives synthon (17), for which we use a malonate ester, and halide (18), available from optically active alcohol (19), a major by-product from fermentation. 

Choose suitable starting materials for syntheses of the inseetioide base for diazinone (43) and the ant alarm pheromone (44). 

On the basis of the method described above, the PAPA machine (i.e., Probabilistic Automatic Pattern Analyser — a combination of photocamera/interface/ computer) has been developed by Amoore, Palmieri and Wanke 4,8), and applied in a study of ant alarm pheromone activity. The 36 radii used for hand calculation of A are substituted within PAPA by a reproducible collection of 4096 randomly selected curves. 

Hydrazones prepared from (S)- l-amino-2-(methoxymethyl)pyrrolidine (242) and acyclic ketones have been shown to undergo deprotonation and alkylation with almost complete asymmetric induction at the a-center (79AG(E)397). The ant alarm pheromone, (+)-(5)-4-methyl-3-heptanone (245), was prepared from the metallated hydrazone of diethyl ketone (243) by alkylation with n-propyl iodide and subsequent cleavage of the crude product via its JV-methyl iodide with acid (Scheme 52). The optical purity of the product was >99%. 

Mimicry by passive transfer Mimicry of ant alarm pheromones Chemical camouflage Review... 

Stoeffler, M Maier, T.S., Tolasch, T. and Steidle, J.L.M. (2007). Foreign-language skills in rove-beetles Evidence for chemical mimicry of ant alarm pheromones in myrmecophilous Pella beetles (Coleoptera Staphylinidae)../. Chem. Ecol., 33, 1382-1392. 

Electrophilic substitution. A number of chiral nucleophilic species have been described that result in optically active a-alkyl aldehydes, ketones, acids, and acid derivatives upon alkylation and (usually) subsequent hydrolytic cleavage. Enders provides a number of examples (Figure 3) one of which results in the ant alarm pheromone, 4-methyl 3-heptanone (26 2 7). Studies by A. I. Meyers of the chemistry of anions of chiral oxazolines (Figure 4) were the first of the genre, however ( 8 ). Related reactions of chiral anions of metalloenamines and hydrazones (29, 30, 31) have in common with the alkylation of oxazolines metallated azaenolate intermediates that predispose one face of an azaenolate double bond to reaction with the electrophile. 

Asymmetric a-alkylatlon of ketones (7, 10-11 8, 16-17). Enders and Eichenauer have now obtained almost complete asymmetric a-alkylation of acyclic ketones by way of hydrazones formed with 1. An example is the synthesis of (+)-(S)-4-methyl-3-heptanone (4), an ant alarm pheromone, from diethyl ketone. The hydrazone 2 was metalated and alkylated with n-propyl iodide in ether to give 3. 

Enders, D., Eichenauer, H. Asymmetric synthesis of ant alarm pheromones - a-alkylation of acyclic ketones with practically complete asymmetric induction. Arrgew. Chem. Int. Ed. Engl. 1979,18, 397. 

Synthesis of the ant alarm pheromone mannicone Examples of Chemoselectivity in Synthesis... 

The synthesis of the ant alarm pheromone mannicone 117 is a good example. Enone disconnection reveals that we need a crossed aldol condensation between the symmetrical ketone 118, acting as the enol component, and the enolisable aldehyde 119. 

Figure 3.10 Natural product synthesis imploying SAMP-RAMP hydrazones 5-(+)-4-methyl-3-heptanone, the leaf cutting ant alarm pheromone [105] serricornin, the sex pheromone of the cigarette beetle [120] S,E-4,6-dimethyl-6-octen-3-one, the defense substance of daddy longlegs [120] (+)-eremophilenolide [120] and antibiotic X-14547A [121], Stereocenters formed by asymmetric alkylation are indicated by. ...

The synthesis d of the ant alarm pheromone (3) used this strategy because the optically active acid (4) was available and only the right enantiomer alarms the ants. 

With two heteroatoms in the ring, it is often easiest to identify a readily available fragment (Table 29.2) containing both heteroatoms and disconnect it from a suitable electrophilic fragment. Hence (24), needed for a synthesis of the ant alarm pheromone mannicone (23), clearly contains hydrazine, NH2NH2. Disconnection reveals keto ester (25). 

Amoore, J.E., Palmieri, G., Wanke, E., and Blum, M.S. (1969) Ant alarm pheromone activity correlation with molecular shape by scanning computer. Science, 165, 1266-1269. 

Wright, R.H. and Brand, J.M., "Correlation of Ant Alarm Pheromone Activity with Molecular Vibration." Nature, 1972, 225-226. 

Sharma KR, Fadamiro HY. Fire ant alarm pheromone and venom alkaloids act in concert to attract parasitic phorid flies, Pseudacteon spp. J Insect Physiol 2013 59 (11) 1119-24. 

Guan and collaborators studied the effect of 14 alkylpyrazines, known to be ant alarm pheromones, in combination with bait on fire ants (Figure 12) (14JAF11924).Testing at a dose range ofO.l—1000ng,it was found that out of the 14 alkylpyrazines, 4 compounds,2,3,5-trimethylpyrazine (88),2,3-diethyl-5-methylpyrazine (89), and a mixture of 2-ethyl-3,6-dimethylpyrazine (90) and 2-ethyl-3,5-dimethylpyrazine (91) promoted a significant increase in the alarm responses. Furthermore, it was determined that out of the mixture of 2-ethyl-3,6-dimethylpyrazine (90) and 2-ethyl-3,5-dimethylpyrazine (91), the former was substantially more active than the latter. 

Used as a flavouring essence. Ant alarm pheromone. Mp 29 . Bp 260-265 , Bpi6 160 . 

To compare the extent to which chirality is induced in a given achiral molecule, Hayward (351) has measured the dichroic and isotropic molar extinction coefficients of the substance when dissolved in two different optically active solvents, and has plotted the ratio of these extinction coefficients in one solvent against the ratio in the other. This was done for a number of aliphatic ketones (351) which previously and independently had been tested as ant alarm pheromones (354). The points for a series of... 

---