5-Ethyl-6-methylheptan-2-one

The two ethyl-homologous carbonyl compounds (286) and (289) have so far only been found in tea oil (49J). The possibility that 5-ethyl-6-methylheptan-2-one (286) originates from the metabolism of a monocyclic monoterpene cannot be excluded (49J), although this ketone seems more likely to be formed by oxidative biodegradation of the sitosterol side chain. Thus, for instance, all the aroma compounds (282) to (291) listed here except (286) and (289) were detected in tobacco oil (777, J42, 306, 463, 590). 

Within Hymenoptera, pheromones produced by workers in social colonies are the best studied across many genera, principally in ants [6], with those eliciting trail following most extensively studied. The distinct behavior and the relative ease of the bioassay have resulted in chemical identifications in many species [ 113,114]. Those that have been recently identified are listed in Table 5. In addition, several alarm and recruitment signals have recently been identified. Many of the compounds recently identified in ants have previously been reported as trail or alarm pheromones in other ant species. For example, methyl 4-methylpyrrole-2-carboxylate 64, 3-ethyl-2,5-dimethylpyrazine 65, (9Z)-hexadec-9-enal 66,4-methylheptan-3-ol 67, and methyl 6-methylsalicy-late 68 have been identified as trail pheromone components, and heptan-2-one 69,4-methylheptan-3-one 70, formic acid 71, undecane 61,4-methylheptan-3-ol 67, methyl 6-methylsalicylate 68, and citronellal 72 have been identified as alarm pheromone components [6]. The use of the same chemicals across genera, with some used for very different functions, is an interesting phenomenon. 

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