A palladium-catalyzed cyanation of alkenyl halides using acetone cyanohydrin is described. A number of structurally diverse alkenylic nitrile containing compounds was prepared in one step under optimized conditions. The reaction proved to be efficient, chemoselective, easy to perform, and tolerant of a number of functional groups.

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Rh(II)-catalyzed oxonium ylide formation-[2,3] sigmatropic rearrangement of α-diazo-β-ketoesters possessing γ-cyclic unsaturated acetal substitution, followed by acid-catalyzed elimination-lactonization, provides a concise approach to 1,7-dioxaspiro[4.4]non-2-ene-4,6-diones. The process creates adjacent quaternary stereocenters with full control of the relative stereochemistry. An unsymmetrical monomethylated cyclic unsaturated acetal leads to hyperolactone C, where ylide formation-rearrangement proceeds with high selectivity between subtly nonequivalent acetal oxygen atoms.

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The sacoglossan mollusc-derived metabolite, tridachiahydropyrone (3), and its proposed biosynthetic precursors (1 and 2) form part of a complex chemical defence system against predators and harmful UV light. Here, we provide supporting biophysical evidence that the metabolites become selectively localised at cell membranes and outline a binding scheme that accommodates the observed data. The possibility that localised lipid domains within the membrane have an effect on the localisation is also addressed.