Total Synthesis, Proof of Absolute Configuration, and Biosynthetic Origin of Stylopsal, the First Isolated Sex Pheromone of Strepsiptera

Abstract

The asymmetric total synthesis of the diastereomers of stylopsal establishes the absolute configuration of the first reported sex pheromone of the twisted-wing parasite Stylops muelleri as (3R,5R,9R)-trimethyldodecanal. The key steps for the diastereo- and enantiodivergent introduction of the methyl groups are two different types of asymmetric conjugate addition reactions of organocopper reagents to α,β-unsaturated esters, whereas the dodecanal skeleton is assembled by Wittig reactions. The structure of the natural product was confirmed by chiral gas chromatography (GC) techniques, GC/MS and GC/electroantennography (EAD) as well as field tests. An investigation into the biosynthesis of the pheromone revealed that it is likely to be produced by decarboxylation of a 4,6,10-trimethyltridecanoic acid derivative, which was found in substantial amounts in the fat body of the female, but not in the host bee Andrena vaga. This triple-branched fatty acid precursor thus seems to be biosynthesized de novo through a polyketide pathway with two consecutive propionate-propionate-acetate assemblies to form the complete skeleton. The simplified, motionless and fully host-dependent female exploits a remarkable strategy to maximize its reproductive success by employing a relatively complex and potent sex pheromone.

We do not select, nor are we choosy: reproductive biology of Strepsiptera (Insecta)

“…Female S. melittae continue to release pheromones until they mate, upon which they immediately and drastically decrease pheromone emission (Tolasch et al ., ). Mated females have only trace amounts of pheromone in their cephalothorax and are not attractive to males (Lagoutte et al ., ).…”

Total Synthesis, Stereochemical Assignment, and Field‐Testing of the Sex Pheromone of the Strepsipteran Xenos peckii

“…Comparison of spectral data derived from these materials to those of the natural pheromone, along with results from a field trapping experiment, unambiguously demonstrate that (3 R ,5 S ,9 R ,7 E ,11 E )‐3,5,9,11‐tetramethyl‐7,11‐tridecadienal is the X. peckii sex pheromone. The pheromone differs both in its unsaturation and termination of the polyketide chain from the recently reported ( R , R , R )‐3,5,9‐trimethyldodecanal ( 2 ) pheromone of the bee parasitoids S. mellittae and S. muelleri . Despite these differences, the two strepsipteran pheromones still bear an astounding resemblance not only in their molecular structure and functional group but also in their stereochemistry, suggesting similar pathways for their biosyntheses.…”

“…[1] She emits al ong-range, male-attractant sex pheromone, which we recently identified as (7E,11E)-3,5,9,11-tetramethyl-7,11-tridecadienal (1) ( Figure 1). [2] While this structurally unusual pheromone resembles that of the bee parasitoids S. mellittae and S. muelleri (Strepsiptera:S tylopidae) [(3R,5R,9R)-trimethyldodecanal (2)], [3][4][5] these two aldehydes (i.e., 1 and 2)a re the only pheromonesknown in the entire order Strepsiptera.…”

Tandem-, Domino- and One-Pot Reactions Involving Wittig- and Horner-Wadsworth-Emmons Olefination

“…As oxidants, activated MnO 2 [43][44][45][46], barium permanganate [47,48], tetra-n-propylammonium perruthenate (TPAP)/N-methylmorpholine N-oxide (NMO) [49][50][51][52][53][54] and TPAP/N,N,N′,N′-tetramethylenediamine dioxide (TMEDAO 2 ) [55], o-iodoxybenzoic acid (IBX) [56][57][58], Dess-Martin periodinane [59][60][61], DMSO-oxalyl chloride (Swern conditions) [62][63][64], DMSO-SO 3 -pyridine (Parikh-Doering oxidation) [38,39] or DMSO-SO 3 -triethylamine [65], pyridinium chlorochromate (PCC) or PCC/celite [66][67][68][69] as well as pyridinium dichromate (PDC) [70] such as PDC encapsulated in sol gel [71] (27) [72], nanoparticulate ruthenium supported on highly porous aluminum oxyhydroxide [73] or on silica gel [74], and nickel nanoparticles [75,76] Tandem-, Domino-and One-Pot Reactions Involving Wittig-and Horner-Wadsworth-Emmons... http://dx.doi.org/10.5772/intechopen.70364using activated MnO 2 [79]. Over the years, this process has been used more often [40,[80][81][82]…”