- Oxidative Deprotection of p-Methoxybenzyl Ethers via Metal-Free Photoredox Catalysis
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An efficient and greener deprotection method for p-methoxybenzyl (PMB) ethers using a metal-free visible light photoredox catalyst and air and ammonium persulfate as the terminal oxidants is presented. Various functional groups and protecting groups were tolerated in the developed method to achieve good to excellent yields in short reaction times. Significantly, the developed method was compatible with PMB ethers derived from primary, secondary, and tertiary alcohols and a gram-scale reaction. Mechanistic studies support a proposed reaction mechanism that involves single electron oxidation of the PMB ether.
- Ahn, Deok Kyun,Kang, Young Woo,Woo, Sang Kook
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p. 3612 - 3623
(2019/03/11)
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- Synthesis of (4: E,6 Z,10 Z)-hexadeca-4,6,10-trien-1-ol and (4 E,6 E,10 Z)-hexadeca-4,6,10-trien-1-ol, the pheromone components of cocoa pod borer moth Conopomorpha cramerella
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A concise and efficient synthesis of the pheromone components of the cocoa pod borer moth, namely (4E,6Z,10Z)-hexadeca-4,6,10-trien-1-ol and (4E,6E,10Z)-hexadeca-4,6,10-trien-1-ol, starting from commercially available materials, was reported. The overall yield was 30.4% and 27.4%, respectively. The stereoselective formation of (E,Z)- or (E,E)-conjugated double bond relied on Sonogashira coupling with (E)-5-bromopent-4-en-1-ol prepared from (E)-5-bromopent-4-enal and the stereoselective hydrogenation of the enyne, while the 10Z-double bond was formed by Wittig reaction from 4-hydroxybutanal and n-hexyltriphenylphosphonium bromide.
- Huang, Fei,Zhang, Yushun,Yao, Yun,Yang, Wanqiu,Tao, Yunhai
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p. 35575 - 35580
(2017/07/28)
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- An Improved and Convenient New Synthesis of the Pheromone Components of the Tomato Leafminer Tuta absoluta
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A convenient new synthesis of the two pheromone components of the tomato pest Tuta absoluta in high overall yields and high stereoselectivity (30% yield, E,Z,Z 97% for the major compound and 23% yield, E,Z 99% for the minor component) is reported. The approaches compare favorably with others previously described.
- Puigmartí, Marc,Bosch, Ma Pilar,Guerrero, Angel
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p. 961 - 968
(2015/03/30)
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- A convenient triisobutylaluminium (TIBAL)-promoted Johnson-Claisen approach to γ,δ-unsaturated alcohols
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Mixed ortho esters derived from allylic alcohols undergo methanol elimination in the presence of triisobutylaluminium (TIBAL) at room temperature to form mixed ketene acetals. TIBAL then promotes immediate Claisen rearrangement of these intermediates, and
- Cosgrove, Kelly L.,McGeary, Ross P.
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experimental part
p. 1749 - 1752
(2009/12/04)
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- One-pot regio- and stereoselective cyclization of 1,2,n-triols
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A simple and efficient process to cyclize triols containing a 1,2-diol functionality with a pendant hydroxyl group is presented. The one-pot procedure converts the 1,2-diol into an ortho ester in situ, which upon treatment with a Lewis acid generates a cyclic acetoxonium intermediate. This intermediate is subsequently trapped by the pendant hydroxyl group to generate a cyclic ether. The stereochemistry of the 1,2-diol is transferred to the product with complete fidelity (inversion at the site of cyclization), and the reaction proceeds with high regioselectivity. The process is akin to the Lewis acid-catalyzed intramolecular ring-opening of epoxides with hydroxyl groups yielding cyclic ethers of various sizes with regio- and stereochemical control. Copyright
- Zheng, Tao,Narayan, Radha S.,Schomaker, Jennifer M.,Borhan, Babak
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p. 6946 - 6947
(2007/10/03)
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- Mammalian exocrine secretions. XII: Constituents of interdigital secretions of bontebok, Damaliscus dorcas dorcas, and blesbok, D. d. phillipsi
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In addition to the nine compounds identified in the interdigital secretion of the bontebok, Damaliscus dorcas dorcas, in a previous study, 76 compounds belonging to different compound types, were identified in the interdigital secretions of the bontebok and the blesbok, D. d. phillipsi. These compounds include alkanes, alcohols, aldehydes, ketones, fatty acids, terpenoids, γ-lactones, an isopropyl ester, long-chain hydroxyesters, 2- substituted pyridines, phenols, steroids, and dimethylsulfone. No qualitative differences were found between secretions from the two sexes or from animals from different habitats. Although no attempt was made to correlate territorial behavior or other behavioral phenomena with the qualitative composition of interdigital secretions from individual animals, available information seems to indicate that quantitative differences probably do not have a major semiochemical function. Only two species of bacteria, Bacillus brevis and Planococcus citreus, were found in the interdigital pouches of male and female members of the two subspecies, regardless of the habitat of the animals. B. brevis synthesized, among other unidentified constituents, (Z)-3-penten-2-ol, 2-hexanone, 2-octanone, 2-nonanone, tetradecanoic acid, pentadecanoic acid, heptadecanoic acid, octadecanoic acid, (Z)-9-hexadecenoic acid, and isopropyl hexadecanoate in vitro, while P. citreus produced, among others, the γ-lactones dodecan-4-olide and (Z)-6-dodecen-4-olide, which is one of the major constituents of the interdigital secretions of both subspecies. Some components of the interdigital secretions are not present in the interdigital glandular tissue, and the possibility is discussed that these compounds could be produced by microbiological activity in the interdigital pouch.
- Burger,Nell,Spies,Le Roux,Bigalke,Brand
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p. 2057 - 2084
(2007/10/03)
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- Identification of the sex pheromone of Scrobipalpula absolute; determination of double bond positions in triple unsaturated straight chain molecules by means of dimethyl disulphide derivatization
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The sex pheromone of Scrobipalpula absoluta (Meyrick) (Lepidoptera: Gelechiidae) was identified as a 92:8 mixture of (3E,8Z,11Z)-3,8,11-tetradecatrienyl acetate (1) and (3E,8Z)-3,8-tetradecadienyl acetate (2) through mass spectrometric investigation of the dimethyl disulphide derivatives of excised sex pheromone glands. It is the first time that this method was used for triple unsaturated straight chain molecules. Compound (2) was identified as a new pheromone component. A synthetic mixture of the two identified compounds proved to be attractive in wind tunnel experiments.
- Griepink, Frans C.,Van Beek, Teris A.,Posthumus, Maarten A.,De Groot, Aede,Visser, J. Hans,Voerman, Simon
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p. 411 - 414
(2007/10/02)
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- A New Synthesis of (Z)-Heneicos-6-en-11-one, Sex Pheromone of Douglas Fir Lepidoptera Orgyia pseudotsugata
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2-Octyn-1-ol (II) on hydrogenation over Lindlar's catalyst provides (Z)-2-octen-1-ol (III).Conversion of III into the corresponding bromide (IV) with PBr3 and subsequent alkylation of ethyl monosodiomalonate with IV in benzene/DMF mixture gives the diester (V) in high yield.Removal of one carbethoxy group of (V) on heating with NaCl/H2O in DMSO affords ethyl 4(Z)-decenoate (VI) which on LAH reduction yields the carbinol (VII).Treatment of VII with PBr3 in dry ether furnishes the bromide (VIII) which easily forms Grignard reagent (IX) with dry Mg turnings in anhyd.THF.The reagent (IX) on reaction with undecanal furnishes (Z)-heneicos-6-en-11-ol (X).Oxidation of X with Corey's reagent provides (Z)-heneicos-6-en-11-one (I).
- Vig, O. P.,Sharma, M. L.,Verma, N. K.,Malik, Neera
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p. 950 - 951
(2007/10/02)
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