- A short synthesis of (Z)-15-methylhexadec-11-enoic acid
-
The biologically intriguing (Z)-15-methylhexadec-11-enoic acid, a component of Myxococcus xanthus and Cyamopsis tetragonolobus, has been synthesized in 19% overall yield via the Wittig reaction of 4-methyl-1-pentyltriphenylphosphonium bromide and 10-bromodecanal. The title compound displayed marginal cytotoxicity against human cervix carcinoma (HeLa) and Chinese hamster ovary (CHO) cells.
- Reyes, Elba D.,Carballeira, Néstor M.
-
-
Read Online
- Tribromoisocyanuric acid/triphenylphosphine: A new system for conversion of alcohols into alkyl bromides
-
An efficient and facile method has been developed for the conversion of alcohols into alkyl bromides under neutral conditions using tribromoisocyanuric acid and triphenylphosphine (molar ratio 1.0:0.7:2.0, alcohol/ tribromoisocyanuric acid/triphenylphosphine) in dichloromethane at room temperature. This method can be applied for the conversion of primary, secondary, benzylic and allylic alcohols, and their corresponding bromides are obtained in 67-82 percent yield. Tertiary alcohols do not react under these conditions.
- De Andrade, Vitor S.C.,De Mattos, Marcio C.S.
-
p. 975 - 979
(2014/06/24)
-
- Synthesis of disparlure analogues, using resolution on microcrystalline cellulose triacetate-I
-
The gypsy moth, Lymantria dispar, uses a chiral epoxide, (+)-(7R,8S)-2-methyl-7,8-epoxyoctadecane, (+)-disparlure, as its main sex attractant. The moths can detect both enantiomers of disparlure and respond differently to each one. In an effort to understand the structure-activity relationships of the gypsy moth olfactory system, we prepared the analogues of (+)- and (-)-disparlure. The key intermediate in route to the analogues was 2-epoxytridecan-1-ol. Herein we report the resolution of 2-epoxytridecan-1-yl esters on microcrystalline cellulose triacetate and the synthesis of 5-oxa and (5Z)-ene analogues of (+)- and (-)-disparlure. An effort to make 5-aza analogues resulted in the formation of anti-5-(1-hydroxy-1-undecyl)-3-(3-methylbutyl) oxazolidin-2-one. The analogues were tested for their electroantennogram responses and for their ability to bind to pheromone-binding protein 1 (PBP1). We found that the 5-oxa analogues gave strong responses and that the antenna and the PBP1 no longer distinguish the enantiomers of the 5-oxa analogues. The analogues all bound the PBP1 with similar affinity to (-)-disparlure.
- Inkster, James A. H.,Ling, Ivy,Honson, Nicolette S.,Jacquet, Loic,Gries, Regine,Plettner, Erika
-
p. 3773 - 3784
(2007/10/03)
-
- Nuapapuin A and sigmosceptrellins D and E: New norterpene cyclic peroxides from a southern Australian marine sponge, Sigmoseeptrella sp.
-
A Sigmosceptrella sp. from the Great Australian Bight, Australia, has yielded the new norditerpene cyclic peroxide, nuapapuin A (2a), and the norsesterterpene cyclic peroxide sigmosceptrellin D (3a), characterized as the corresponding methyl esters 2b and 3b. The crude methylated sponge extract also yielded the new norsesterterpene cyclic peroxide sigmosceptrellin E methyl ester (4). Relative stereochemistry about C2, C3, and C6 was assigned by established empirical rules and absolute stereochemistry by the advanced Mosher procedure. A plausible biosynthetic pathway has been proposed that rationalizes key transformations in the biosynthesis of all known norterpene cyclic peroxides and related norterpene ketones, dienes and sigmosceptrins.
- Ovenden, Simon P. B.,Capon, Robert J.
-
p. 214 - 218
(2007/10/03)
-
- Asymmetric synthesis of A-factor
-
The synthesis of enantlopure A-factor ['autoregulatory factor'; (3R)-(-)-2-(6-methylheptanoyl)-3-hydroxymethylbutano-4-lactone] by the completely diastereoselective benzyloxymethylation of (4R)-3-(3-phenylpropanoyl)-4-isopropyloxazolidin-2-one is reported.
- Crawforth, James M.,Fawcett, John,Rawlings, Bernard J.
-
p. 1721 - 1725
(2007/10/03)
-
- Enantioselective synthesis of α-methyl carboxylic acids using a DiTOX chiral auxiliary
-
Five α-methyl carboxylic acids have been prepared with high e.e.s using 1,3-dithiane 1-oxide (DiTOX) units as the stereocontrolling elements and sources of chirality.
- Page, Philip C. Bulman,McKenzie, Michael J.,Allin, Steven M.,Klair, Sukhbinder S.
-
p. 13149 - 13164
(2007/10/03)
-
- Neutral Compounds from Male Castoreum of North Americal Beaver, Castor canadensis
-
North American beavers (Castor canadensis) mark their territories with castoreum, the strong-smelling paste in their castor sacs. In their own territories, beavers respond with scent marking to experimental scent marks that consist of strange castoreum (or selected components). In part, the unique odor of castoreum is due to large amounts of phenolic compounds and neutral compounds. Purified neutral compounds were analyzed by GC, GC-MS, and NMR; identities of the neutral compounds were confirmed by comparing the properties of authentic compounds with those of the isolated compounds. We identified 13 neutral compounds that had not been reported before for castoreum. Most of these are oxygen-containing monoterpens. Of the nine neutral compounds reported by Lederer (1949), only three are confirmed in our analysis; the other six neutral compounds are either absent or are not volatile enough to be detected by our methods. Eight compounds - 6-methyl-1-heptanol, 4,6-dimethyl-1-heptanol, isopinocamphone, pinocamphone, two linalool oxides, and their acetates - were synthesized for structure identification and bioassays.
- Tang, Rong,Webster, Francis X.,Mueller-Schwarze, Dietland
-
p. 1745 - 1762
(2007/10/03)
-
- Studies related to fatty acid desaturation. Part I: Preparation of methyl-substituted nonanols, nonyl bromides and total synthesis of new branched oleic acids
-
Convenient pathways for the synthesis of seven structurally defined isomers of methyl-nonanols and methyl-nonylbromides are described.These synthons are used to perform Wittig reactions between convenient phosphoranes and aldehydes in order to obtain seven new octadecenoic acids bearing a methyl grouping on carbons 11 to 17. branched nonan-1-ols / branched 1-nonylbromides / Wittig reactions / methyl 9-bromononanoate / methyl 8-formyloctanoate / methyl 11 or 17-methyloctadec-9-enoates
- Genard, S.,Patin, H.
-
p. 397 - 406
(2007/10/02)
-
- The Synthesis and Mesomorphic Properties of 4-Methyl-Pentyloxyphenylthio-4'-Substituted Benzoates
-
Three different series of branched chain alkoxy thioesters of the type p-X-C6H4-C(O)S-C6H4-p-O(CH2)mCH(CH3)(CH2)nCH3 with m = 0-3, n = 3-0; X = R, RO and C9CO2 and R varying between C6 and C12 were synthesized by esterification of 4-substituted benzoic acids with the branched chain alkoxy thiol using the carbodiimide method.Mesomorphic properties were determined by hot-stage polarizing microscopy and compared with those for analogous straight-chain thioesters.Clearing temperatures were always lower in the branched chain than in the straight chain series, but the amount of lowering decreased as the methyl group was moved out along the branched chain away from the benzene ring.Melting temperatures were more variable, as expected, often showing little variation between the 1,2 and 2,1 isomers but increasing considerably for the 3,0 isomer until temperatures were either equal to or slightly higher than those in the straight-chain compounds.The smectic C phase was enhanced usually at the expense of the nematic phase.Nematic-smectic C combinations predominated with the smectic A phase occurring as a short phase range only in the RO-2,1 and X = R series.The most mesophases were usually observed in the 2,1 series; moving the methyl group further out along the chain tended to give restoration of the nematic phase as the predominant phase.The biphenyl thioester p-C8H17O-C6H4-C6H4-C(O)S-C6H4-p-OCH2CH2CH(Me)Et was also synthesized and showed an enantiotropic sequence of SC, SA and N phases with a monotropic smectic G phase which supercooled considerably.Transition temperatures were all > 100 deg C.The thiols with m > 0 were prepared by alkylation of sodium 4-hydroxybenzene-sulfonate with the branched chain bromide, conversion to the sulfonyl chloride and reduction to the thiol.When m = 0, synthesis was by alkylation of 4-bromophenol with the branched chain bromide, treatment with cuprous thiobutane and cleavage of the butyl group with NaNH2.
- Neubert, M. E.,Shenouda, I. G.
-
-
- A New Synthesis of (Z)-7,8-Epoxy-2-methyloctadecane (Disparlure)
-
Alkylation of the dianion of propargyl alcohol with 1-bromodecane in Li/liq.NH3 affords tridec-2-yn-1-ol (II) which on hydrogenation in the presence of Lindlar's catalyst yields tridec-2Z-en-1-ol (III).Treatment of III with MsCl/Et3N in anhyd.CH2Cl2 at low temperature gives the mesylate (IV) which undergoes smooth coupling reaction with 1-bromo-4-methylpentane (V) to produce 2-methyloctadec-7Z-ene (VI).Reactions of VI with m-chloroperbenzoic acid in anhyd.CH2Cl2 furnishes the title compound (I).
- Vig, O. P.,Sharma, M. L.,Kumari, Sarla,Vohra, Neelam
-
p. 860 - 861
(2007/10/02)
-
- Microbial Oxidation of Sterol Side-Chains
-
Several sterol metabolising microorganisms, Pseudomonas convexa, P. stutzeri, Micrococcus sp., Cephalosporium longisporum and Moraxella sp. were isolated from soil on 2-cyclopentyl-6-methyl heptane and cholestane as carbon sources.All these organisms were shown to have the capacity of oxidizing the eight carbon side chain of cholesterol.Excepting P. convexa, the organisms needed a chelating agent for prevention of steroid ring degradation.The Moraxella sp. proved to be the most versatile as it degraded cholesterol derivatives such as 3β-methoxy cholest-5-ene, 3β-chloro cholest-5-ene, 3,5-cyclocholestan-6-one and potassium cholesteryl sulphate to the corresponding 17-keto steroids in 10-50percent yield in shake flasks.It also gave high yields of estrone from both 19-hydroxy-3β-acetoxy cholest-5-ene and 19-hydroxy-3β-acetoxy sitost-5-ene.Two new enzymes one carrying out the oxidative O-demethylation of 6β-methoxy 3,5-cyclocholestane and the other, the isomerisation of i-steroids to normal 3β-hydroxy-Δ5 steroids were discovered.Immobilized Moraxella cells in agar carried out the side chain degradation of cholesteryl sulphate to yield 3β-hydroxy androst-5-en-17-one sulphate and the 19-hydroxy-3β-acetoxy derivatives of both cholesterol and sitosterol to estrone in high yields.The half life of entrapped cells was estimated to be 28 days.
- Bhattacharyya, P. K.,Rao, M. Krishna,Natarajan, Rama Devi,Ramgopal, Malathi,Madyastha, Prema,Madyastha, K. M.
-
-