Hemiacetal pheromone

The hemiacetal pheromone was first prepared in low yield as a mixture of isomers (Scheme 20) [108]. Thus, oxidative coupling of the dianion of ( )-3-hexenoic acid 127 and LiAlH4 reduction of the resulting diacid produced a mixture of diols from which the EyE-meso isomer 128 could be separated. The meso... 

Determination of absolute configuration (2). hemiacetal pheromone of Biprorulus bibax... 

Suzuki T, Morita K, Ikemiyagi H, Watanabe K, Hiroi K, Katoh T (2006) Synthesis of the hemiacetal pheromone of the spined citrus bug biprorulus bibax utilizing an iridium catalyzed oxidative lactonization. Heterocycles 69 457-461... 

Scheme 27 summarizes Yamamoto s synthesis of lardolure (16), the aggregation pheromone of the acarid mite, Lardoglyphus konoi [45]. The key-step was the transformation of acetal A to hemiacetal B. 

Hemiacetal 25 [(3 ,4S,l E)-3,4-bis(r-butenyl)tetrahydro-2-furanol] is the male pheromone of the spined citrus bug (Biprorulus bibax). Scheme 38 summarizes Mori s synthesis of 25 [61]. Claisen rearrangement (A B) and lipase-catalyzed asymmetric acetylation [meso-C >(5S,6R)-D] were the two key steps of the synthesis. Further purification of D was executed at the stage of its crystalline derivative E. In this particular case, the unnatural (3S,4R,l E)-25 was as active as the natural (3R,4S,VE)-25. Accordingly, a more efficient synthesis of ( )-25 was achieved by the rearrangement of F, avoiding the use of toxic HMPA [62]. 

Synthesis of Oxygen Heterocycles (Excluding Epoxides, Hemiacetals, Lactones and Acetals) as Pheromones... 

Photolysis of the hypoiodite of hemiacetal 139 results in carbon-carbon bond cleavage to produce an iodolactone 140, Eq. 96 [83], The iodoalkyl side chain was subsequently homologated to afford the sex pheromone of the rove beetle. 

Different alcohols and protected alcohols (as hemiacetals, silyl, methoxymethyl or phenyl ethers) were lithiated at the d-position to give the corresponding organolithium compounds. In the case of alcohols, a previous deprotonation of the hydroxyl functionality is required. The chiral intermediate 197 was prepared from the phenylsulfanyl derivative 196 first by deprotonation followed by carbon-sulfur bond cleavage with LiDTBB at low temperature. The reaction of the dianionic system 197 with y- and d-lactones in the presence of cerium(III) salts gave, after hydrolysis, spiroketal pheromones 198 (Scheme 2.27) [163]. 

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