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Macrolide lactones, the so called cucujolides derived from unsaturated fatty acids, are aggregation pheromones of cucujid grain beetles. Thirty years ago, Oehlschlarger et al. showed that (3Z,6Z)-dodeca-3,6-dien-11-olide (4) and the respective 12-olide (7) attract the sawtoothed grain beetle Oryzaephilus surinamensis, whereas (5Z,8Z,13R)-tetradeca-5,8-dien-13-olide (5) increases the response synergistically. The frass of this beetle is attractive for its parasitoid Cephalonomia tarsalis, which potentially can be used for pest control. A GC/MS analysis of attractive frass showed the presence of 5, together with an unknown isomer. Cucujolide V was tentatively identified also in the femoral glands, pheromone-releasing structures, of the Madagascan mantelline frog Spinomantis aglavei. Therefore, a new route to synthesize doubly unsaturated macrolides allowing the flexible attachment of the side chain was developed. A straightforward method to obtain Z configured macrolides involves ring-closing alkyne metathesis (RCAM) followed by Lindlar-catalyzed hydrogenation. This methodology was extended to homoconjugated diene macrolides by using RCAM after introduction of one Z configured double bond in the precursor by Wittig reaction. A tungsten benzylidyne complex was used as the catalyst in the RCAM reaction, which afforded the products in high yield at room temperature. With the synthetic material at hand, the unknown isomer was identified as the new natural product (5Z,8Z,12R)-tetradeca-5,8-dien-12-olide, cucujolide X (8). Furthermore, the route also allowed the synthesis of cucujolide V in good yield. The natural products were identified by the synthesis of enantiomerically pure or enriched material and gas chromatography on chiral phases. The new macrolide (R)-8 proved to be biologically active, attracting female O. surinamensis, but no males. The synthetic material allowed the identification of (R)-5 in both the beetle and the frog., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Pollination by sexual deception is arguably one of the most unusual liaisons linking plants and insects, and perhaps the most illustrative example of extreme floral specialization in angiosperms. While considerable progress has been made in understanding the floral traits involved in sexual deception, less is known about how this remarkable mimicry system might have arisen, the role of pre-adaptations in promoting its evolution and its extent as a pollination mechanism outside the few groups of plants (primarily orchids) where it has been described to date. In the Euro-Mediterranean region, pollination by sexual deception is traditionally considered to be the hallmark of the orchid genus Ophrys. Here, we introduce two new cases outside of Ophrys, in plant groups dominated by generalized, shelter-mimicking species. On the basis of phylogenetic reconstructions of ancestral pollination strategies, we provide evidence for independent and bidirectional evolutionary transitions between generalized (shelter mimicry) and specialized (sexual deception) pollination strategies in three groups of flowering plants, and suggest that pseudocopulation has evolved from pre-adaptations (floral colours, shapes and odour bouquets) that selectively attract male pollinators through shelter mimicry. These findings, along with comparative analyses of floral traits (colours and scents), shed light on particular phenotypic changes that might have fuelled the parallel evolution of these extraordinary pollination strategies. Collectively, our results provide the first substantive insights into how pollination sexual deception might have evolved in the Euro-Mediterranean region, and demonstrate that even the most extreme cases of pollinator specialization can reverse to more generalized interactions, breaking 'Cope's rule of specialization'.