Nasutitermes octopilis

J.W. Lauher, and M.S. Collins Two New Tetracyclic Diterpenes from the Defense Secretion of the Neotropical Termite Nasutitermes octopilis. Tetrahedron Lett. 3827-3830 (1979). 

A range of monoterpenes has been identified from Nasutitermes species (Prestwich, 1979 Baker and Walmsley, 1982) of which a-pinene, /J-pinene, limonene, terpinolene, and myrcene are the most common. In Trinervitermes gratiosus, intraspecific variations occur (Prestwich, 1978) in allopatric populations from Kenya. Major soldiers produce a-pinene. Minor soldiers from two populations produce a-pinene, -pinene, camphene, and limonene, but only a-pinene in the other group. More pronounced variations occur in the diterpenes, and populations of this species and T. bettonianus (Prestwich and Chen, 1981) are easily distinguished on the basis of the diterpene profiles of major and minor soldiers (Fig. 16.15). These population differences are not due to diet, and injection of labelled precursors (Prestwich et al., 1981) into Nasutitermes octopilis has demonstrated that the soldiers are capable of synthesizing the mono- and diterpenoid components of their secretion. 

Total syntheses of diterpenoid hydrokempenones have been accomplished by Paquette et al.,f using the Pd-catalyzed [3 + 2] cycloaddition methodology. One example is outlined on Scheme 43 and describes the synthesis of an isomeric compound 208 of 3/3-hydroxy-7/3-kemp-8(9)-en-6-one, a defense secretion agent of the neotropical species Nasutitermes octopilis. 3-AUcoxy-2-cyclohexenone 204 was efficiently functionalized and transformed to bicylic adduct 205 via a Robinson annulation reaction. Reduction of the double bond followed by condensation of dimethyl carbonate and oxidation gave the keto ester 206, which was treated with [2-(acetoxymethyl)-3-allyl]trimethylsilane, palladium acetate, and triisopropyl phosphite in refluxing tetrahydrofuran to afford a 98% yield of 207. Substituted methylenecyclopentane 207 was then functionalized by stereoselective reduction and protections, and final closure was done under basic conditions after an ozonolysis step. A modified Barton-McCombie reaction produced the desired tetracyclic adduct 208. 

Thirty-nine diterpenes from frontal glands of termites are listed by Wheeler and Duffield in Handbook of Natural Pesticides Vol. IVB, Pheromones (ed. Morgan and Mandava, CRC Press, Boca Raton, 1985, pp. 159), more have been isolated since. It is clear these are insect-produced via the isoprenoid route. When the soldiers of Nasutitermes octopilis were injected with C-labelled acetic acid or mevalonolactone, the C was incorporated into tri- and tetra-cyclic diterpenes (Prestwich, Jones and Collins, Insect Biochemistry, 1981,11, 331). 

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See also in sourсe #XX -- [ ]

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