Terpenoids double bond activation

Although various transition-metal complexes have reportedly been active catalysts for the migration of inner double bonds to terminal ones in functionalized allylic systems (Eq. 3.2) [5], prochiral allylic compounds with a multisubstituted olefin (Rl, R2 H in eq 2) are not always susceptible to catalysis or they show only a low reactivity [Id]. Choosing allylamines 1 and 2 as the substrates for enantioselective isomerization has its merits (1) optically pure citronellal, which is an important starting material for optically active terpenoids such as (-)-menthol, cannot be obtained directly from natural sources [6], and (2) both ( )-allylamine 1 and (Z)-allylamine 2 can be prepared in reasonable yields from myrcene or isoprene, respectively, The ( )-allylamine 1 is obtained from the reaction of myrcene and diethylamine in the presence of lithium diethylamide under Ar in an almost quantitative yield (Eq. 3.3) [7], The (Z)-allylamine 2 can also be prepared with high selectivity (-90%) by Li-catalyzed telomerization of isoprene using diethylamine as a telomer (Eq. 3.4) [8], Thus, natural or petroleum resources can be selected. 

Introducing a sulfur atom to the carbonyl significantly increased the activity of the resulting compounds (B) on JHE and some but not all other esterases, possibly by bioisosterically mimicking Q5) the a,ft double bond of the natural JHs. Based on this finding, a series of aliphatic, aromatic (2,8.) and terpenoid (9) derivatives were synthesized. The most active compound of these series was 3-octylthio-l,1,l-trifluoro-2-propanone (OTFP). 

More epoxides (1) with juvenile hormone activity (Vol. 2, p. 7) have been made by epoxidizing the Wittig products of citronellal (2), and some of these substances also increase silk production.Reduction of the double bond sometimes increases the activity against Oncopeltus fasciatus. Insecticidal activity is also reported for certain terpenoid cyclopropanes [e.g. (3), made from limonene and ethyl diazoacetate] and for isobornyl thiocyanoethyl ether (made from cam-phene and ethylene chlorohydrin followed by treatment with potassium thiocyanate). The insect-repelling activity shown by thujic acid amides (4) is... 

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