Insect pheromones and their analogs. XIV. Synthesis of muscalure ? The sex pheromone ofMusca domestica

Odinokov, V. N.; Ishmuratov, G. Yu.; Balezina, G. G.; Bakhitov, R. Sh.; Толстиков, Г. А.

doi:10.1007/bf00574217

Cited by 2 publications

(3 citation statements)

References 8 publications

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“…This spectrum is in agreement with previously reported spectral data. 37 Hept-3-yn-1-yl(methyl)sulfane (7). Hept-3-yn-1-yl(methyl)sulfane was synthesized using a literature procedure 34 in 14% yield.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Mechanistic Studies of Formal Thioboration Reactions of Alkynes

et al. 2017

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Several formal heteroborylative cyclization reactions have been recently reported, but little physical-organic and mechanistic data is known. We now investigate the catalyst-free formal thioboration reaction of alkynes to gain mechanistic insight into B-chlorocatecholborane (ClBcat) in its new role as an alkynophilic Lewis acid in electrophilic cyclization/dealkylation reactions. In kinetic studies, the reaction is second order globally; first order with respect to both the 2-alkynylthioanisole substrate and the ClBcat electrophile, with activation parameters of ΔG‡ = 27.1 ± 0.1 kcal mol−1 at 90 °C, ΔH‡ = 13.8 ± 1.0 kcal mol−1 and ΔS‡ = −37 ± 3 cal mol−1 K−1, measured over the range of 70–90°C. Carbon kinetic isotope effects supported a rate-determining AdE3 mechanism wherein alkyne activation by neutral ClBcat is concerted with cyclative attack by nucleophilic sulfur. A Hammett study found a ρ+ of −1.7, suggesting cationic charge buildup during the cyclization and supporting rate-determining concerted cyclization. Studies of the reaction with tris(pentafluorophenyl)borane (B(C6F5)3), an activating agent capable of cyclization but not dealkylation, resulted in the isolation of a post-cyclization zwitterionic intermediate. Kinetic studies via UV-vis spectroscopy with this boron reagent found second order kinetics, supporting the likely relevancy of intermediates in this system to the ClBcat system. Computational studies comparing ClBcat with BCl3 as an activating agent showed why BCl3, in contrast to ClBcat, failed to mediate the complete the cyclization/demethylation reaction sequence by itself. Overall, the results support a mechanism in which the ClBcat reagent serves a bifunctional role by sequentially activating the alkyne, despite being less electrophilic than other known alkyne-activating reagents, then providing chloride for post-rate-determining demethylation/neutralization of the resulting zwitterionic intermediate.

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Section: ■ Results and Discussionmentioning

confidence: 99%

“…Hept-3-yn-1-yl 4-methylbenzenesulfonate was synthesized using a literature procedure 37 in 58% yield. 1 H NMR (CDCl3, 600 MHz): δ 7.80 (d, J = 7.8 Hz, 2H), 7.34 (d, J = 7.7 Hz, 2H), 4.06 (q, J = 7.3 Hz, 2H), 2.51 (d, J = 7.1 Hz, 2H), 2.45 (s, 3H), 2.5 (d, J = 7.9 Hz, 2H), 1.44 (quin, J = 7.2 Hz, 2H), 0.92 (t, J = 7.4 Hz, 3H).…”

Section: Methodsmentioning

confidence: 99%

Mechanistic Studies of Formal Thioboration Reactions of Alkynes

et al. 2017

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“…The synthesis of components of G. molesta sex pheromone has been reported [3,4,[10][11][12][13][14][15]. The shortest pathway to the acetylene compounds consists of Wittig olefination of 8-acetoxyoctanal by n-butyltriphenylphosphonium bromide.…”

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confidence: 99%

Novel convenient synthesis of (Z/E)-8-dodecenyl acetates, components of the Grapholitha molesta sex pheromone

Huang

Lü

et al. 2006

Chem Nat Compd

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Insect pheromones and their analogs. XIV. Synthesis of muscalure ? The sex pheromone ofMusca domestica

Cited by 2 publications

References 8 publications

Mechanistic Studies of Formal Thioboration Reactions of Alkynes

Mechanistic Studies of Formal Thioboration Reactions of Alkynes

Novel convenient synthesis of (Z/E)-8-dodecenyl acetates, components of the Grapholitha molesta sex pheromone

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