Stereospecific Synthesis of (E,Z)- and (Z,Z)-Hexadeca-10,12-dienal. Sex Pheromone Components of Diaphania hyalinata

Abstract

Isomeric ( E , Z )-and ( Z , Z )-hexadeca-10,12-dienal were prepared, stereospecifically, in 51% and 43% overall yields from dec-1-yne.Diaphania hyalinata and Diaphania nitidalis are pyralid species that exhibit similar life cycles and habits. The former feeds upon the foliage of pumpkin and other cucurbits, 2 whereas the latter is particularly destructive to cantaloupe, cucumber and muskmelon. 3 The damage caused make these crops unsuitable for marketing. The isomers ( E , Z )-hexadeca-10,12-dienal (1) and ( Z , Z )-hexadeca-10,12-dienal (2) were isolated, as minor components, from the extracts of ovipositors of female melonworm, D. hyalinata , 2 while trace amounts of 1 were found in extracts from pickleworm adults of D. nitidalis . 3 These compounds, along with others, represent essential components of the sex pheromones of these species. Previous syntheses of the ( E , Z )-isomer 1 have involved Wittig condensation of butyltriphenylphosphorane with ( E )-12-(2-tetrahydropyranyloxy)dodec-2-enal, 4 followed by oxidation. The major drawback of this procedure is the generation of a mixture of E and Z isomers in the Wittig reaction. The ( Z , Z )-isomer has been prepared by the Ca-diotÐChodkiewicz coupling of pent-1-yne with undec-10yn-1-ol, followed by reduction of the triple bond with dicyclohexylborane to the corresponding dienol. 2 The alcohols ( E , Z )-and ( Z , Z )-hexadeca-10,12-dien-1-ol have been synthesized stereospecifically, by the palladium-catalyzed cross-coupling reaction between an hydroxyalkenylborane and the appropriate haloalkene in the presence of a base. 5 The overall %yields reported for the syntheses of these alcohols, from undec-10-en-1-ol, are 41 and 27% respectively. 5 In this paper we report stereospecific syntheses of the isomeric dienals 1 and 2 in 51 and 43% overall yields from dec-1-yne (3) . The syntheses utilized the common precursor tert -butyldimethylsilyl undec-10-ynyl ether (6) which was prepared from dec-1-yne (3) by coupling of its lithium acetylide with paraformaldehyde, at low temperature, to give undec-2-yn-1-ol ( 4 ) in 93% (Scheme 1). The latter was isomerized to undec-10-yn-1-ol (5) in 98% by a zip-Stereospecific Synthesis of ( E , Z )-and ( Z , Z )-Hexadeca-10,12-dienal.

New Synthesis of (11Z,13Z)-11,13-Hexadecadienal, the Female Sex Pheromone of the Navel Orangeworm

“…7) Among these six syntheses, four of them introduced the formyl group by final oxidation of 1-hexadecadienol with either pyridinium chlorochromate (PCC) 2,4,5) or pyridinium dichromate (PDC). 7) Bishop and Morrow recorded a synthesis of 2.8 kg of 1, in which the formyl group was introduced into their intermediate as a diethylacetal, and final deprotection afforded 1.…”

“…The construction of the (Z,Z)-conjugated diene system has been achieved in the past by a number of different protocols: the Wittig reaction coupled with partial hydrogenation of acetylene, 2) hydroboration-protonolysis of 1,3-diyne, 4) diimide reduction of acetylene and palladium-catalyzed coupling, 5) organocopper chemistry, 6) palladium-catalyzed coupling and hydroborationprotonolysis, 7) and copper-catalyzed Grignard coupling and hydroboration-protonolysis. 8) A critical examination of all the published syntheses indicates that the preparation of 1 in a multi-gram-scale was not an easy task due to the non-reproducibility of some of the earlier works.…”

“…A solution of dicyclohexylborane was prepared by adding dropwise a boranedimethyl sulfide complex (1.8 ml, d 1.287, 2.3 g, 30 mmol) to a stirred and ice-cooled solution of cyclohexene in dry THF (2 M, 26 ml, 52 mmol) at 5-10 C under argon. The mixture was stirred for 30 min at [5][6][7][8][9][10] C to give a slurry of crystalline dicyclohexylborane. A solution of 9 (2.7 g, 8.8 mmol, 5 ml) was added dropwise to the stirred and ice-cooled mixture.…”

Metal‐Catalyzed Cross‐Coupling Reactions of Organoboron Compounds with Organic Halides

“…Alkenyl-alkynyl coupling reactions provides a method for synthesizing such enynes or dienes (Scheme 2-50). The reaction between (E)-1-alkenylborane and 1-bromo-1-alkyne stereoselectively provides (E)-enyne (208), which is then converted into (E,Z)-hexadeca-10,12-dienal, a sex pheromone of the melon worm [323]. On the other hand, (Z)-enyne (210) is obtained from the correspond-ing coupling reaction of the (Z)-1-alkenylboron compounds (209) [324].…”

Crystal structures and biological activity of 1,1,4-triphenyl-substituted 1,3-enyne compounds

“…1,3-Enynes are also very useful building blocks in organic synthesis (Geary et al, 2012;Cabezas & Oehlschlager, 1999).…”