Broad-horned flour beetle

The aggregation pheromone of the broad-horned flour beetle (Gnatocerus cornutus) was reported to be (lJR,4i, 5S)-(+)-acoradiene (33) by Tebayashi et al. [72]. Scheme 47 shows Mori s synthesis of (lRy4Ry5S)-33 [73]. The key-step was the ring-closing olefin metathesis of A to give B. An X-ray analysis of C confirmed the structure shown. The product (lJR,4JR,5S)-33, however, was different... 

While the pheromones of Tenebrio and Tribolium originate from a mixed biosynthesis, those produced by males of the broad horned flour beetle, Gnatho-cerus cornutus, represent true terpenes. Initially, the configuration of this new pheromone had been erroneously proposed to be (IR,4R,5S) a-acoradiene [325] however, independent syntheses of pure stereoisomers [326,327] proved the correct structure to show (lS,4A,5A)-configuration 165. The scope of the synthesis is shown by Mori (see chapter by Mori in volume 1 and [15]). A minor component of the G. cornutus was reported to be a-cedren-14-al 166 [328]. 

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