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Tricarbonylcyclohexadienyliron salts of type (2; R2 = +), after reaction successively with a P-diketone or a pketo-ester and manganese dioxide or lead dioxide, give tricarbonyl-cis-3a.7a-dihydrofuraniron complexes of type (3). Use of deuteriated intermediates indicated that the cyclisation occurs with specific loss of the 6-endoproton.THE reactions with nucleophiles of some carboniuni salts derived from tricarbonylcyclohexadieneiron derivatives have been r e p ~r t e d . ~, ~ Such processes are potentially useful in organic synthesis if the tricarbonyliron group can be removed in good yield. This question is discussed el~ewhere,~ the usual reagents being iron(rr1) chloride or cerium(1v) salts.that manganese dioxide removes the tricarbonyliron group from its complex with 1methoxycyclohexa-1,3-diene (l), but not from the coniplex with 2-methoxycyclohexa-l,3-diene (2; R2 = H, R1 = OMe), in experiments with a mixture of the two dieiie complexes. We have now separated these complexes chromatographically, and have confirmed the original observations, although (1) was oxidised to give anisole rather than l-methoxycyclohexa-1,3-diene and (2; R1 = ORk, R2 = H) was relatively stable.In order to investigate further the capabilities of the We have reported

The oil of Santalum spicatum (R.Br.) A.DC. has been fractionated to yield 10-cis- (1) and 10-trans-2,6,10-trimethyldodeca-2,6,10-triene (2). These compounds have been synthesized by reduction of a mixture of cis- and trans-farnesyl acetate. Although not identical with the trail pheromone of Nasutitermes they have similar specific trail activities, the former being the more active.

Das Konzept von überlagerter lateraler Kontrolle ("superimposed lateral control") von Reaktivität, Stereochemie und Struktur durch Verknüpfung von komplexierten Metallatomen mit olefinischen Systemen wird entwickelt und diskutiert.