Stereochemical studies on pheromonal communications

Abstract

Pheromonal communications are heavily dependent on the stereochemistry of pheromones. Their enantioselective syntheses could establish the absolute configuration of the naturally occurring pheromones, and clarified the unique relationships between absolute configuration and bioactivity. For example, neither the (R)- nor (S)-enantiomer of sulcatol, the aggregation pheromone of an ambrosia beetle, is behaviorally active, while their mixture is bioactive. Recent results as summarized in the present review further illustrate the unique and diverse relationships between stereochemistry and bioactivity of pheromones.

Attraction of Redbay Ambrosia Beetle, Xyleborus Glabratus, To Leaf Volatiles of its Host Plants in North America

“…The vast majority of the identified compounds in leaf and wood redbay volatiles were chiral, however, the enantiomeric composition of these volatiles was not determined in this study. Given that stereochemical properties of enantiomers impacts odor and other biological activities, such as insect behavior (Brenna et al 2003;Mori 2014), enantiomeric compositions of wood and leaf volatiles of Laureacea coupled with behavioral bioassays should be conducted to determine if specific enantiomers are more effective attractants for X. glabratus. Nonetheless, our field trapping data proved that the blend of available synthetic chemicals tested here was attractive to X. glabratus.…”

The Lutzomyia longipalpis complex: a brief natural history of aggregation-sex pheromone communication

“…This is particularly pertinent if there are multiple sympatric species using pheromones as their primary mode of communication. The specificity of the message can be achieved in a multitude of ways including variation in overall composition, the presence and composition of stereoisomers [11, 12] or the ratio of specific components all of which may lead to qualitative and quantitative differences in the signal emitted [5, 13, 14]. Even subtle changes in the pheromone blend (the specific ratios of chemicals within a pheromone) [15] or partitioning of communication channels through temporal or seasonal differences in pheromone production and emission as well as shifts in circadian activity [16–18] may result in individuals being unable to detect one another [9, 18, 19] and thus lead to speciation.…”

“…Many insect semiochemicals are chiral compounds where the biological activity of each enantiomer differs, where the “unnatural” enantiomer (that not produced by the insect) may be equally active, less active (but enhancing the activity of the natural isomer) or even inhibiting the activity of the active isomer [11]. Our understanding of the stereospecificity of either CEMB-1 or CEMB-2 molecules is incomplete.…”

Practical Synthesis of both Enantiomeric Amino Acid, Mannich, and Aldol Derivatives by Asymmetric Organocatalysis

“…For example, both enantiomers of naturally occurring limonene smell differently; ( S )‐limonene smells of lemons, while enantiomeric ( R )‐limonene smells of oranges . In addition, insects use chiral chemical messengers (pheromones) as sex attractants; one of the enantiomers of the insect pheromone, olean, attracts male fruit flies, while its enantiomer operates on the female of the species . Hence, biology is quite sensitive to chirality and the activity of drugs also depends on which enantiomer is utilized.…”