Asymmetric total synthesis of a putative sex pheromone component from the parasitoid wasp Trichogramma turkestanica

Abstract

SummaryVirgin females of the parasitoid wasp Trichogramma turkestanica produce minute amounts of a sex pheromone, the identity of which has not been fully established. The enantioselective synthesis of a putative component of this pheromone, (6S,8S,10S)-4,6,8,10-tetramethyltrideca-2E,4E-dien-1-ol (2), is reported as a contribution to this identification. Catalytic asymmetric conjugate addition of methylmagnesium bromide and stereoselective Horner–Wadsworth–Emmons olefinations are used as the key steps, and 2 was obtained in 16 steps with an overall yield of 4.4%.

Structure elucidation of female-specific volatiles released by the parasitoid wasp Trichogramma turkestanica (Hymenoptera: Trichogrammatidae)

“…However, ozonolysis of a natural sample [ 29 ] containing the two compounds, followed by reductive work-up, would yield syn , syn -2,4,6-trimethylnonanol, the enantiomers of which can be easily separated by using heptakis-[2,3-di- O -methyl-6- O -( tert -butyldimethylsilyl)]-β-cyclodextrin (50% in OV1701) as the stationary GC phase, operated at 100 °C. Under these conditions, the (2 S ,4 S ,6 S )-enantiomer [ 30 ] is the later eluting stereoisomer, giving an α-value of ( t r 2 : t r 1 ) = 1.019 (see Supporting Information File 1 , Figure S4).…”

Strategies for the Synthesis of Deoxypropionates

“…26 The monooxygenase seems to be also involved in N-oxidation and dihydration to give borrelidin (16). Strong support for this hypothesis came from the recent isolation of borrelidin B (35) by Linington 27 from a Streptomyces species from marine sediment.…”

“…Subsequent base-catalyzed isomerization yielded the α,β-unsaturated thioester 59, which could be submitted to catalytic 1,4-addition giving either syn-product 60 in 83% yield (syn/anti 96:4, 92% ee) or the corresponding anti-product 61 in 77% yield (syn/anti 8:92, 85% ee) depending on the type of Josiphos ligand (+)-47a and (-)-47a, respectively. Catalytic conjugate additions were applied by Minnaard and Feringa to a variety of other target molecules such as (-)-lardolure (6), 34 the putative pheromone component (6S,8S,10S)-4,6,8,10-tetramethyltrideca-2E,4E-dien-1-ol of a parasitoid wasp, Trichogramma turkestanica, 35 and phthioceranic acid (11a). 36 Following a similar approach, Loh reported the synthesis of siphonarienal (1), siphonarienone (2) and the stereotriad C14-C20 of antibiotic TMC-151 A utilizing TolBINAP as the chiral ligand instead of the Josiphos ligand 47.…”

Chiral methyl-branched pheromones

“…330 The rst insect spiroketal is chalcogran, with no methyl branches but an ethyl branch, released from a bark beetle. 331 The methyl-branched spiroacetals act as a male sex pheromone of fruit ies and bark beetles (105 and 106), a female sex pheromone of wild bees (109), an aggregation pheromone of a shield bug (110), and a defense substance of wasps, walking sticks, and rove beetles (107, 108, and 111). The mono-and dimethyl spiroacetals (105)(106)(107)(108)(109) are biosynthesized by the cyclization of unbranched 2-ketones, 332,333 but the biosynthetic precursors of the trimethyl spiroacetals (110 and 111) have a methyl branch.…”

“…Recently, this reaction was used for the synthesis of (6S,8S,10S)-35. 110 Commercially available Tol-BINAP [2,2 0 -bis(di-p-tolylphosphino)-1,1 0 -binaphthyl] is another useful ligand that was employed for synthesizing the (3R,5S)-3,5-dimethyl pheromone (92) (R-4-4c). 278 The rst methylation of (E)-2-decenoate used the (S)-ligand, and the second methylation of (E)-5-methyl-1-dodecenoate, which was obtained by a two-step reaction, used the (R)-ligand.…”