- Stereospecific syntheses of sex pheromones of the californian red scale and white peach scale (Homoptera: Diaspididae) based on 1,4-cis-hydrogenation of dienes
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Stereospecific syntheses of (+/-)-3-methyl-6-isopropenyl-3(Z),9-decadien-1-yl acetate and (+/-)-3,9-dimethyl-6-isopropenyl-3(Z),9-decadien-1-yl propionate (the Racemoc forms of the pheromones of the scales Aonidiella aurantii and Pseudaulascaspis pentagona) with a geometrical purity of the (Z)-trisubstituted double bond not lower than 99percent were performed.The key step in both syntheses was the 1,4-cis-hydrogenation of the corresponding ethyl 3-methyl-6-(1,1-ethylenedioxyethyl)-2,4,9-decatrienoates catalyzed with chromium carbonyl complexes.These 2,4-dienes were obtained in five conventional steps including the alkylation of ethyl acetoacetate by the appropriate 1-bromo-3-butenes and the Horner-Emmons olefination of the corresponding α-branched aldehydes. - Keywords: (+/-)-3-methyl-6-isopropenyl-3(Z),9-decadien-1-yl acetate, (+/-)-3,9-dimethyl-6-isopropenyl-3(Z),9-decadien-1-yl propionate, synthesis, aldehydoketals, ethyl 2,4-alkadienoates, 1,4-cis-hydrogenation, the Horner-Emmons olefination, ethyl acetoacetate, alkylation, arene chromium tricarbonyl complexes
- Vasil'ev, A. A.,Vlasyuk, A. L.,Kryshtal, G. V.,Serebryakov, E. P.
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- Highly efficient terpenoid pheromone syntheses via regio-and stereocontrolled processing of allyllithiums generated by reductive lithiation of allyl phenyl thioethers
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Previous work had shown that reducuve lithiation of allyl phenyl thioethers, followed by transmetallation, produces allylmetallics which react selectively with carbonyl compounds at the most or least substituted terminus; the latter results in mainly cis olefin. This technology allows extremely efficient syntheses of racemic versions of lavandulol (two-pot, 70% yield), the Comstock mealy bug pheromone (one-pot, 45% yield) and the California red scale pheromone (4-steps, 23% yield).
- McCullough, Dennis W.,Bhupathy,Piccolino, Elvio,Cohen, Theodore
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p. 9727 - 9736
(2007/10/02)
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- Carbon-carbon bond formation employing organoiron reagents. Syntheses of lavandulol and red scale pheromone
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Some aspects of the chemistry of (η1-allyl)Fp complexes [Fp =η5-C5H5Fe(CO)2] are briefly reviewed, especially the means available for their elaboration. The range of electrophiles which react with (η1-allyl)Fp complexes has been enlarged to include allyl iodides. Two examples of this reaction are given, the first leading to lavandulol 9, the second providing a short synthesis of the red scale pheromone (R,S-15).
- Celebuski,Rosenblum
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p. 5741 - 5746
(2007/10/02)
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- Charge-Directed Conjugate Addition Reactions in the Preparation of Substituted Methyl Ketones
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Charge-directed conjugated addition reactions of the tert-butyl esters of α,β-unsaturated acylphosphoranes 2 have been used to prepare a variety of substituted methyl ketones.Substituted ylides 6 are prepared by alkylating ylide anions 4 generated by the addition of nucleophiles to 2 and are converted under acidic conditions to substituted (acylmethylene)phosphoranes 12 which are hydrolyzed to methyl ketones.The utility of these unsaturated acylphosphoranes as methyl vinyl ketone equivalents in conjugate addition-alkylation reactions is demonstrated in a synthesis of the racemic form of the sex pheromone of the California red scale, 14.
- Cooke, Manning P.,Burman, Diana L.
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p. 4955 - 4963
(2007/10/02)
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