30434-65-2Relevant academic research and scientific papers
Improved synthesis of the pheromone of the longtailed mealybug
Zou, Yunfan,Millar, Jocelyn G.
, p. 2319 - 2321 (2010)
A short and efficient synthesis of the longtailed mealybug pheromone featuring an Ireland-Claisen rearrangement as the key step is described.
Sex Pheromone of the Invasive Mealybug Citrus Pest, Delottococcus aberiae (Hemiptera: Pseudococcidae). A New Monoterpenoid with a Necrodane Skeleton
Vacas, Sandra,Navarro, Ismael,Marzo, Javier,Navarro-Llopis, Vicente,Primo, Jaime
, p. 9441 - 9449 (2019)
Native to sub-Saharan Africa, Delottococcus aberiae De Lotto (Hemiptera: Pseudoccidae) is an invasive mealybug that has been recently reported in Europe, seriously damaging citrus production in eastern Spain. In this study, we isolated and determined the structure of the sex pheromone of D. aberiae, to provide a highly specific and effective lure for detecting, monitoring, and potentially controlling this pest. The volatile profile of D. aberiae virgin and mated females was studied by aeration and collection of effluvia in Porapak-Q. The resulting extracts were analyzed by gas chromatography coupled to mass spectrometry (GC-MS), revealing a candidate compound specific of virgin females. GC-MS and nuclear magnetic resonance spectroscopy data evidenced a new compound, (4,5,5-trimethyl-3-methylenecyclopent-1-en-1-yl)methyl acetate, with an unusual β-necrodol skeleton. This compound was synthesized and shown to be attractive to male D. aberiae in both laboratory and field experiments. A GC analysis using an enantioselective stationary phase and polarimetry analyses of the synthetic enantiomers showed the natural compound emitted by virgin females to be the-enantiomer.
Sex pheromone of the longtailed mealybug: A new class of monoterpene structure
Millar, Jocelyn G.,Moreira, Jardel A.,McElfresh, J. Steven,Daane, Kent M.,Freund, Amy S.
, p. 2683 - 2685 (2009)
The sex pheromone of the longtailed mealybug, identified as 2-(1,5,5-trimethylcyclopent-2-en-1-yl)ethyl acetate, represents the first example of a new monoterpenoid skeleton. A [2,3]-sigmatropic rearrangement was used in a key step during construction of the sterically congested tetraalkylcylopentene framework.
The chemoselective cyclisation of unsymmetrical γ-diketones to cyclopentenones by ditected aldol reaction using a magnesium chelate
Cadman, Michael L. F.,Crombie, Leslie,Freeman, Stephen,Mistry, Jayshree
, p. 1397 - 1408 (2007/10/02)
The feasibility of synthesising disubstituted cyclopent-2-enones chemoselectively from unsymmetrical γ-diketones, using an aldol reaction directed by magnesium chelation, has been studied.Treatment of 3,3-dimethylhexane-2,5-dione 15 with aqueous sodium hydroxide (0.5 mol dm-3) gives a mixture of 3,5,5-trimethyl- 12 and 3,4,4-trimethylcyclopent-2-enone 14 in an isomer ratio 2.2:1.Insertion of an α-methoxycarbonyl grouping as a control element allows formation of a magnesium chelate 17 when treated with magnesium methoxide, and the major product is then mainly the undehydrated aldol 21.This, when treated with aqueous sodium hydroxide (0.5 mol dm-3) to dehydrate, hydrolyse and decarboxylate, gives the 3,5,5-trimethyl- and 3,4,4-trimethylcyclopent-2-enones in a nearly chemospecific ratio of 1:49.When 3-methoxycarbonyl-4,4-dimethylhexane-2,5-dione 16 is treated with aqueous sodium hydroxide (0.5 mol dm-3), omitting the magnesium methoxide treatment, the corresponding ratio of cyclopentenones was still an interesting 1:7.3.Treatment with sodium methoxide in methanol gives, by contrast γ-lactone 27.Treatment of undecane-4,7-dione 34 with aqueous sodium hydroxide (0.5 mol dm-3) at reflux gives 2,3-dipropylcyclopent-2-enone 36 and 3-butyl-2-ethylcyclopent-2-enones 35 in a ratio of almost 1:1.Treatment of 6-methoxycarbonylundecane-4,7-dione 33 with magnesium methoxide in methanol gives undehydrated aldol which when treated with aqueous sodium hydroxide gives the dipropylcyclopent-2-enone 36 and 3-butyl-2-ethylcyclopent-2-enones 35 in 9:1 ratio.Conversely, the 5-methoxycarbonyldione 32 gives a corresponding ratio of 36 to 35 of 1:9.The best ratios attained, 1:15 for 36 and 35 from 32 and 20:1 for 36 and 35 from 33, were when magnesium methoxide in refluxing benzene or toluene were employed.There is still a strong chemoselective effect when the magnesium treatment is omitted.Preliminary examination of the corresponding cyclohex-2-enone systems gave poorer chemoselectivities when either procedure was employed. 6-Methoxycarbonyldodecane-5,9-dione 52 gave 2,3-dipropyl-54 and 3-butyl-2-ethyl-cyclohex-2-enone 55 in a ratio of ca. 4:1 whilst the 5-methoxycarbonyldodecane-4,8-dione 53 gave a 1: ca. 4 ratio.
Nazarov Reaction of Trisubstituted Dienones: Mechanism Involving Wagner-Meerwein Shift
Motoyoshiya, Jiro,Yazaki, Toshikazu,Hayashi, Sadao
, p. 735 - 740 (2007/10/02)
The Nazarov reactions of trisubstituted α,α'-dienones were studied.Whereas α,β-dimethyl-β'-alkyl α,α'-dienones gave 2,3-dimethyl-4-alkyl-2-cyclopentenones when heated in concentrated sulfuric acid, the reaction of β,β-dimethyl-β'-alkyl α,α'-dienones afforded 3,4-dimethyl-4-alkyl-2-cyclopentenones as the rearranged products.A mechanistic investigation using two deuterated dienones suggests that the Nazarov reactions of the latter dienones are accompanied by Wagner-Meerwein shifts to form the most stable carbocations.
Keto ethers. IV. Products formed on reaction of dihydro-2,2,5,5-tetramethyl-3(2H)-furanone with strong acids
Yates, Peter,Burke, Patrick Michael
, p. 1695 - 1704 (2007/10/02)
Reaction of tetrahydro-2,2,5,5-tetramethyl-3(2H)-furanone (1) with 96 or ca. 100percent sulfuric acid or hot polyphosphoric acid followed by aqueous quenching gave the following products: 2-hydroxy-2,5-dimethyl-4-hexen-3-one (3), 2,4,4-trimethyl-2-cyclopenten-1-one (7), 3,5,5-trimethyl-2-cyclopenten-1-one (8), tetrahydro-2,3,5,5-tetramethylfuran-2,3-diol (11), 2,5-dihydro-3,5,5-trimethyl-2-methylenefuran (17) and its dimer 20, 2,5-dihydro-2,3,5,5-tetramethyl-2-furanol (18), 4-hydroxy-2,4-dimethyl-2-pentenoic acid γ-lactone (22), 2,3,5-trimethyl-2-cyclopenten-1-one (23), and tetramethylfuran (25).In 96percent sulfuric acid the products arise by ring opening, ring opening followed by reclosure to carbocyclic products, methyl migration from C-2 to C-3 to give rearranged furan derivatives, and oxidation.In ca. 100percent sulfuric acid or hot polyphosphoric acid further methyl migrations can occur to give 23 and 25.
