Structural and synthetic studies of termite defence chemicals

The defensive secretions of three species of West Africantermite, Macrotermes bellicosus, Macrotermes subhyalinus and Ancistrotermes cavithorax have been studied; all these species were collected in Nigeria. In each case emphasis was placed onthe volatile constituents of the secretions, and analysis performed on sub-milligram quantities using a number of microscale techniques.The soldier caste of M.bellicr,sus was shown to contain amixture of naphthalene and p-toluquinone within the defence secretion whereas M.subhyalinus utilized long-chain hydrocarbons. Extensive studies have been made into the defence secretion of A.cavithorax following initial segregation of the major and minor soldier castes. The main constituent from the major soldiers was found to be a novel, bicyclic furanosesquiterpenoid named ancistrofuran. Smaller amounts of abicyclic sesquiterpenoid dialdehyde were also present accompanied by c - and p -cyclogeraniolene and toluene. In contrast, the secretion from the minor soldiers was found to contain exclusively, a novel mono cyclofarn esyl dialdehyde named ancistrodial. The structures assigned to ancistrodial and ancistrofuran have been confirmed by total synthesis. For the latter, the synthesisof a trans-ring Junction for the bicyclic system was required and extensive studies have been made into methods of formation of derivatives with this feature and the corresponding cisanalogues, which are somewhat more stable. Accordingly, the corresponding phenyl-substituted analogues of ancistrofuranand its congeners have been prepared. During the course of this work, extensive studies on the methods of cyclic ether formation were carried out.