Synthesis of Both Enantiomers of 6-Methyl-3-octanone, An Alarm Pheromone of Ants of the Genus<i>Crematogaster</i>

Naoshima, Yoshinobu; Hayashi, Daijiro; Ochi, Marina

doi:10.1080/00021369.1988.10868852

Cited by 3 publications

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“…The bromide 6 was prepared as a Grignard reagent and then reacted with propionyl morpholine to get (S)-6-methyl-3-octanone (1) in 84.5% yield, and the overall yield of (S)-1 was 43.0%. In these reactions, the stereocenter of the compounds was not touched, and the spectral data of (S)-1 were in accord with the literature, as well as the specific rotation value [3].…”

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confidence: 80%

mentioning

confidence: 99%

“…6-Methyl-3-octanone was isolated and identified as a component of the alarm pheromone of Grematogaster ants [2], a pest causing serious losses of croppers throughout the world. Since effective and cost-efficient control of Grematogaster ant populations can be foreseen with the aid of the alarm pheromone, several total syntheses of the racemate and the (R) enantiomer or (S) enantiomer have been published [2][3][4][5].Recently, our group has undertaken a research program on preparation of chiral auxiliaries [6-8] and application of them to synthesize the insect pheromones [9,10]. In this paper, we have developed an efficient procedure to stereoselectively synthesize (S)-6-methyl-3-octanone (1) via a key step of asymmetric Michael addition using optically pure (4S)-4-benzyloxazolidinone as chiral auxiliary (Scheme 1).…”

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confidence: 99%

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Stereoselective synthesis of an alarm pheromone of Grematogaster ants using (4S)-4-benzyloxazolidinone as chiral auxiliary

Zhou

Chen

et al. 2010

Chem Nat Compd

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547.72.74 (S)-6-Methyl-3-octanone, a component of the alarm pheromone of Grematogaster ants, was synthesized through a key step of stereoselective Michael addition reaction using (4S)-4-benzyloxazolidinone as chiral auxiliary. The target product was obtained with an overall yield of 43.0% over six steps in high enantiomeric purity.Several insects show a remarkable ability to distinguish the stereoisomers of their chiral pheromone components [1]. For instance, specificity of response to the enantiomers of their alarm pheromones has been demonstrated for the leaf cutting ants, Atta texana and Atta cephalotes, and the myrmicine ant, Pogonomyrmex barbatus. 6-Methyl-3-octanone was isolated and identified as a component of the alarm pheromone of Grematogaster ants [2], a pest causing serious losses of croppers throughout the world. Since effective and cost-efficient control of Grematogaster ant populations can be foreseen with the aid of the alarm pheromone, several total syntheses of the racemate and the (R) enantiomer or (S) enantiomer have been published [2][3][4][5].Recently, our group has undertaken a research program on preparation of chiral auxiliaries [6-8] and application of them to synthesize the insect pheromones [9,10]. In this paper, we have developed an efficient procedure to stereoselectively synthesize (S)-6-methyl-3-octanone (1) via a key step of asymmetric Michael addition using optically pure (4S)-4-benzyloxazolidinone as chiral auxiliary (Scheme 1).

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confidence: 99%

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confidence: 99%

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Stereoselective synthesis of an alarm pheromone of Grematogaster ants using (4S)-4-benzyloxazolidinone as chiral auxiliary

Zhou

Chen

et al. 2010

Chem Nat Compd

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“…The filtrate was evaporated to afford 5 (0.86 g, 92%). The IR and NMR spectra were identical to those in the literature [3].…”

Section: S-methylhexanal (5)mentioning

confidence: 98%

L-(-)-Menthol in the Synthesis of Key Synthons for Optically Active Methyl-Branched Insect Pheromones

et al. 2005

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A synthesis of optically active 4S-methylhexanal, 1-bromo-3S-methylheptane, and 1-bromo-3S-methylundecane, which are key synthons for several methyl-branched insect pheromones, that is based on chemically selective transformations of 6-tosyloxy-and 6-iodoisopropyl-4R-methylhexanoates that are available from L-(-)-menthol was proposed.Key words: L-(-)-menthol, 6-tosyloxy-and 6-iodoisopropyl-4R-methylhexanoates, 4S-methylhexanal, 1-bromo-3S-methylheptane, 1-bromo-3S-methylundecane, insect pheromones, synthon, synthesis.We previously reported the synthesis of chiral synthons 6-tosyloxy-(2) and 6-iodo-(3) isopropyl-4R-methylhexanoates from L-(-)-menthol (1) [1]. These were used in the present work to synthesize optically pure 4S-methylhexanal (5), 1-bromo-3S-methylheptane (11), and 1-bromo-3S-methylundecane (12), which are key intermediates for the alarm pheromone of ants of the Cremotogaster and Myrmica genera (6), sex pheromones of the peach leafminer Lyonetia clerkella (13), and pine sawflies of the Diprion and Neodiprion genera (14), respectively. The syntheses of these were also reported [2].In order to prepare 4S-methylhexanal (5), tosyloxyester 2 was converted by hydride reduction, which occurred at both esters, into 4S-methylhexan-1-ol (4), which was oxidized further by the Corey method. The resulting aldehyde (5) was transformed into the pheromone (6) by the literature method [3].Compounds 11 and 12 were synthesized using catalyzed cross-coupling of the iodoester (3) with Grignard reagents 7 and 8, which were generated from ethyl-or n-hexylbromides, to give the isopropyl ester of 4S-methyloctanoic (9) or 4S-methyldodecanoic (10) acid, respectively. Alkaline hydrolysis of esters 9 and 10 with subsequent Hunsdiecker reaction of the resulting acids produced 1-bromo-3S-methylheptane (11), which was converted to the sex pheromone of the peach leafminer (13) as before [4], and 1-bromo-3S-methylundecane (12), a key synthon for the sex pheromone of pine sawflies (14) [5], respectively.Thus, the proposed synthesis of optically pure 4S-methylhexanal, 1-bromo-3S-methylheptane, and 1-bromo-3S-methylundecane, which are key synthons for several methyl-branched insect pheromones, is based on chemically selective transformations of 6-tosyloxy-and 6-iodoisopropyl-4R-methylhexanoates, which are available from L-(-)-menthol.

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“…Several syntheses of this compound as the racemate and an enantiomer are known [2][3][4][5][6]. However, many of them involve several steps and most are labor-intensive and require costly starting materials.…”

Section: Dzhemilevmentioning

confidence: 99%

One-Step Synthesis of Racemic 6-Methyloctan-3-One, an Alarm Pheromone Component of Ants of the Genus Crematogaster

2015

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Dzhemilev6-Methyloctan-3-one (1) was identified as a component of the alarm pheromone of ants of the genus Crematogaster [1]. Several syntheses of this compound as the racemate and an enantiomer are known [2][3][4][5][6]. However, many of them involve several steps and most are labor-intensive and require costly starting materials.We developed a convenient and effective synthetic pathway for a racemic analog of 1 that was based on our recently proposed regioselective carbonylation of 1-alkenes using Et 2 Zn and TaCl 5 catalyst [7].The reaction of but-1-ene with Et 2 Zn in the presence of TaCl 5 (Et 2 Zn-but-1-ene-TaCl 5 = 110:100:5; Et 2 Zn concentration 1.0 mmol/mL in hexane, 20°C, 5 h) formed organozinc compound 2. For this, hexane (20 mL) was cooled to -15°C and treated with but-1-ene (2.25 ml, 20 mmol) cooled to -30°C. Then, the solution was cooled to -15-20°C, treated with Et 2 Zn (2.25 mL, 22 mmol) and TaCl 5 (0.4 g, 1 mmol), heated gradually to room temperature, stirred for 5 h, cooled to -5°C, and treated dropwise with propionylchloride (3, 1.74 mL, 20 mmol) in hexane. All these operations were performed under a dry Ar atmosphere. The resulting reaction mixture was stirred for 2 h and treated with aqueous HCl solution (10%). The resulting 1 was extracted by Et 2 O (3 u 50 mL). The extracts were dried over anhydrous MgSO 4 . The solvent was distilled off. The residue was chromatographed (SiO 2 , hexane) to afford 1 (2.69 g, 99% pure) in 95% yield based on 3 (Scheme 1).The structure of 1 was proven using IR, PMR, and 13 C NMR spectral methods and GC-MS in addition to comparison with an authentic sample [6]. REFERENCES 1.R. M. Crewe, M. S. Blum, and C. A. Collingwood, Comp.

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Synthesis of Both Enantiomers of 6-Methyl-3-octanone, An Alarm Pheromone of Ants of the GenusCrematogaster

Cited by 3 publications

References 1 publication

Stereoselective synthesis of an alarm pheromone of Grematogaster ants using (4S)-4-benzyloxazolidinone as chiral auxiliary

Stereoselective synthesis of an alarm pheromone of Grematogaster ants using (4S)-4-benzyloxazolidinone as chiral auxiliary

L-(-)-Menthol in the Synthesis of Key Synthons for Optically Active Methyl-Branched Insect Pheromones

One-Step Synthesis of Racemic 6-Methyloctan-3-One, an Alarm Pheromone Component of Ants of the Genus Crematogaster

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