Scent glands chemistry

A prominent characteristic of most true bugs is their use of defensive chemicals produced in specialized scent glands, usually found in the abdomen in im-matures, and in the metathorax in adults. However, this pattern is not absolute species that feed on poisonous plants from which they sequester toxic chemical defenses tend to have reduced or modified glands [8,26-28]. Many of these species are also aposematic, vividly advertising their toxicity to would-be predators. The defensive chemistry of bugs has been the subject of a number of reviews [4,6,8,9,12,29,30] and will only be summarized here, with a focus on compounds with interesting or unusual chemistry. 

The chemistry shown in Eq. (21) uses a / -amino selenide as a radical precursor. /S-Amido radical cyclizations in which y -amido selenides served as the radical precursors have also been reported. One example has been described within the context of an approach to the ABC-ring system of manzamine A [47]. Another appears in an efficient synthesis of indolizidine 72, a component of castoreum derived from the Canadian beaver scent gland (Eq. 22) [48]. It is notable that allylic strain plays a role in the latter free-radical cyclization, as the furyl residue undoubtedly occupies an axial site on the incipient tetrahydropiperidone ring. 

Lederer, E. 1946. Chemistry and biochemistry of the scent glands of the beaver Castor fiber). Nature, 157, 231-232. 

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