- Amberlyst A 21 as new and efficient surface catalyst for the cleavage of 2-nitrocycloalkanones
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Ring cleavage of 2-Nitrocycloalkanones with methanol/Amberlyst A 21 gave methyl ω-nitroalkanoates, O2NCH2(CH2)(n)CO2Me where n = 3-6, 8-10,13, in high yield. Subsequent Nef reaction gave the corresponding ω-oxo compounds which were isolated, in the case of methyl 7-oxoheptanoate and methyl 8-oxooctanoate only, or reduced directly with sodium borohydride to give ω-hydroxyalkanoates. A new formal synthesis of exaltolide (15-pentadecanolide) is also reported.
- Ballini,Petrini,Polzonetti
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Read Online
- An efficient synthesis of (R)-(+)-recifeiolide and related macrolides by using enantiomerically pure (R)-(-)-5-methyl-2,2,2-triphenyl-l,2λ5- oxaphospholane
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E-(R)-(+)-8-Dodece- 11-olide, which is known as recifeiolide, was synthesized by a six-step reaction starting from (R)-(+)-propene oxide in a total yield of 53 %. The key step of this synthesis is the preparation of (R)-(-)-methyl 11-hydroxy-8-dodecenate using (R)-(-)-5-methyl-2,2,2- triphenyl-1,2λ5-oxaphospholane. By using this method, enantiomerically pure 13- and 14-membered macrolides were also synthesized.
- Okuma, Kentaro,Hirabayashi, Syun-ichi,Ono, Masaaki,Shioji, Kosei,Matsuyama, Haruo,Bestmann, Hans J.
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- Ozone: A versatile reagent for solid phase synthesis
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Ozone is a versatile reagent which is well adapted to solid phase synthesis: terminal double bonds can he efficiently converted into alcohols, aldehydes or carboxylic acids depending on the reaction conditions.
- Sylvain, Catherine,Wagner, Alain,Mioskowski, Charles
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Read Online
- Synthesis of 1-octacosanol and GC-C-IRMS discrimination of samples from different origin
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Lately, long-chain primary alcohols have been investigated in depth on account of their biological activities. In particular, 1-octacosanol (C 28H57OH), the main component of policosanol, the hypolipidaemic fatty alcohol mixture obtained from sugar cane wax, has been the subject of a multitude of pharmacological studies. The aim of this work was to search a convenient synthetic protocol for the preparation of 1-octacosanol in a gram scale. The key step was a Wittig reaction between the octadecyltriphenylphosphonium ylide and the methyl 10-oxodecanoate. Some steps were further improved by power ultrasound and microwave irradiation, either alone or in combination. Our methodology is suitable for a rapid generation of homologues by varying the chain length in the alkyl halide. Due to the high commercial value, a series of 1-octacosanol samples, either isolated from natural sources or from synthesis (different origin and suppliers), were analysed by gas chromatography-combustion-isotopic ratio mass spectrometry (GC-C-IRMS) and according to the carbon isotopic content, classified on the basis of their origin.
- Cravotto, Giancarlo,Calcio Gaudino, Emanuela,Barge, Alessandro,Binello, Arianna,Albertino, Andrea,Aghemo, Costanza
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- A ROUTE TO LARGE CARBOCYCLES USING AN ALICYCLIC CLAISEN REARRANGEMENT.
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A potentially general route to large carbocycles is described involving a Claisen rearrangement of silyl enolates derived from appropriate unsaturated macrolides.
- Cameron, Andrew G.,Knight, David W.
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- Novel Photooxidation of Alkenes Sensitized by p-Dimethoxybenzene
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Photoexcited p-dimethoxybenzene catalyses oxidative cleavage of various alkenes to corresponding carbonyls in the presence of oxygen.
- Bhalerao, Uday T.,Sridhar, Madabhushi
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Read Online
- Identification and biosynthesis of (E,E) -10,12-Tetradecadienyl acetate in spodoptera littoralis female sex pheromone gland
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A miner component of the sex pheromone gland of the Egyptian cotton leafworm, Spodoptera littoralis, has been identified as (E,E)-10,12-tetradecadienyl acetate. Structural elucidation has been carried out by isobutane-chemical ionization mass spectrometry of the fatty acyl biosynthetic precursor-derived methyl ester. To assign the stereochemistry of the double bonds, the four isomers of both 10,12-tetradecadienyl acetates and methyl 10,12-tetradecadienoates have been synthesized and their gas chromatography retention times and mass spectra have been compared to those of the corresponding natural compounds. Mass-labeling experiments showed that the (E,E)-10,12-tetradecadienoyl moiety is biosynthetically derived from (Z)-11-tetradecenoic acid in the insect pheromone gland.
- Navarro, Isabel,Mas, Esther,Fabrias, Gemma,Camps, Francisco
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Read Online
- A General Approach to Intermolecular Olefin Hydroacylation through Light-Induced HAT Initiation: An Efficient Synthesis of Long-Chain Aliphatic Ketones and Functionalized Fatty Acids
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Herein, an operationally simple, environmentally benign and effective method for intermolecular radical hydroacylation of unactivated substrates by employing photo-induced hydrogen atom transfer (HAT) initiation is described. The use of commercially available and inexpensive photoinitiators (Ph2CO and NHPI) makes the process attractive. The olefin hydroacylation protocol applies to a wide array of substrates bearing numerous functional groups and many complex structural units. The reaction proves to be scalable (up to 5 g). Different functionalized fatty acids, petrochemicals and naturally occurring alkanes can be synthesized with this protocol. A radical chain mechanism is implicated in the process.
- Guin, Joyram,Paul, Subhasis
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supporting information
p. 4412 - 4419
(2021/02/05)
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- NEMATODE DETERRENT COMPOSITIONS
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The present disclosure provides compositions comprising a nematode deterrent comprising a compound of Formula I. Also provided are related articles of manufacture, uses and methods.
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Paragraph 0019; 0136
(2020/01/08)
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- DIHYDROOROTIC ACID DEHYDROGENASE INHIBITOR
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The present invention provides a novel dihydroorotic acid dehydrogenase inhibitor which is applicable to various diseases. When used as an active ingredient, a compound represented by formula (I): (wherein X represents a halogen atom, R1 represents a hydrogen atom, R2 represents an alkyl group containing 1 to 7 carbon atoms, R3 represents -CHO, and R4 represents -CH2-CH=C(CH3)-R0 (wherein R0 represents an alkyl group containing 1 to 12 carbon atoms which may have a substituent on the terminal carbon and/or on a non-terminal carbon, etc.)), an optical isomer thereof or a pharmaceutically acceptable salt thereof has a high inhibitory effect on dihydroorotic acid dehydrogenase and can be used as an immunosuppressive agent, a therapeutic agent for rheumatism, an anticancer agent, a therapeutic agent for graft rejection, an antiviral agent, an anti-H. pylori agent, a therapeutic agent for diabetes or the like.
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Paragraph 0072; 0073; 0074
(2015/04/15)
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- Precise supramolecular control of selectivity in the Rh-catalyzed hydroformylation of terminal and internal alkenes
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In this study, we report a series of DIMPhos ligands L1-L3, bidentate phosphorus ligands equipped with an integral anion binding site (the DIM pocket). Coordination studies show that these ligands bind to a rhodium center in a bidentate fashion. Experiments under hydroformylation conditions confirm the formation of the mononuclear hydridobiscarbonyl rhodium complexes that are generally assumed to be active in hydroformylation. The metal complexes formed still strongly bind the anionic species in the binding site of the ligand, without affecting the metal coordination sphere. These bifunctional properties of DIMPhos are further demonstrated by the crystal structure of the rhodium complex with acetate anion bound in the binding site of the ligand. The catalytic studies demonstrate that substrate preorganization by binding in the DIM pocket of the ligand results in unprecedented selectivities in hydroformylation of terminal and internal alkenes functionalized with an anionic group. Remarkably, the selectivity controlling anionic group can be even 10 bonds away from the reactive double bond, demonstrating the potential of this supramolecular approach. Control experiments confirm the crucial role of the anion binding for the selectivity. DFT studies on the decisive intermediates reveal that the anion binding in the DIM pocket restricts the rotational freedom of the reactive double bound. As a consequence, the pathway to the undesired product is strongly hindered, whereas that for the desired product is lowered in energy. Detailed kinetic studies, together with the in situ spectroscopic measurements and isotope-labeling studies, support this mode of operation and reveal that these supramolecular systems follow enzymatic-type Michaelis-Menten kinetics, with competitive product inhibition.
- Dydio, Pawel,Detz, Remko J.,Reek, Joost N. H.
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supporting information
p. 10817 - 10828
(2013/08/23)
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- NOVEL DIHYDROXYBENZENE DERIVATIVES AND ANTIPROTOZOAL AGENT COMPRISING SAME AS ACTIVE INGREDIENT
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Novel compounds below are useful for preventing or treating diseases caused by protozoans. At least one of a compound represented by Formula (I) (wherein, X represents a hydrogen atom or a halogen atom; R1 represents a hydrogen atom; R2 represents a hydrogen atom or a C1-7 alkyl group; R3 represents -CHO, -C(=O)R5, -COOR5 (wherein R5 represents a C1-7 alkyl group), -CH2OH or -COOH; and R4 represents a C1-16 alkyl group having one or more substituents on a terminal carbon atom and/or non-terminal carbon atom(s), a C2-16 alkenyl group having one or more substituents on a terminal carbon atom and/or non-terminal carbon atom(s), or a C2-16 alkynyl group having one or more substituents on a terminal carbon atom and/or non-terminal carbon atom(s)), an optical isomer thereof, and a pharmaceutically acceptable salt is used.
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Paragraph 0082-0084
(2013/09/26)
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- Palladium-catalyzed reduction of carboxylic acids to aldehydes with hydrosilanes in the presence of pivalic anhydride
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A palladium catalyst system that allows the reduction of carboxylic acids to the corresponding aldehydes with hydrosilanes as reducing agent and pivalic anhydride as an indispensable reagent has been developed. A simple mixture of commercially available bis(dibenzylideneacetone)palladium(0) [Pd(dba) 2], tri(para-tolyl)phosphane and methylphenylsilane realized the reduction of various aliphatic carboxylic acids as well as benzoic acids to aldehydes in good to high yields. Copyright
- Fujihara, Tetsuaki,Cong, Cong,Terao, Jun,Tsuji, Yasushi
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supporting information
p. 3420 - 3424
(2013/12/04)
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- Palladium-catalyzed reduction of acid chlorides to aldehydes with hydrosilanes
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An efficient synthesis of aldehydes from acid chlorides with hydrosilanes as a reducing agent in the presence of a palladium catalyst has been achieved. A simple mixture of commercially available Pd(dba)2 and Mes 3P as a catalyst realized the reduction of various acid chlorides including aliphatic acid chlorides and a, P-unsaturated acid chlorides to the corresponding aldehydes in good to high yields under mild reaction conditions. Georg Thieme Verlag Stuttgart ? New York.
- Fujihara, Tetsuaki,Cong, Cong,Iwai, Tomohiro,Terao, Jun,Tsuji, Yasushi
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supporting information
p. 2389 - 2392
(2013/07/19)
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- Divergent process for C10, C11 and C12 ω-amino acid and α,ω-dicarboxylic acid monomers of polyamides from castor oil as a renewable resource
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Polyamides have great potentials for diverse applications and the present production of their monomers mostly relies on resources from fossil fuel. Starting from undecylenic acid, a natural resource, we have developed both divergent and efficient processes for C10, C11 and C 12 ω-amino acid and α,ω-dicarboxylic acid monomers of the polyamides.
- Koh, Moo-Hyun,Kim, Hyeonjeong,Shin, Nara,Kim, Hyun Su,Yoo, Dongwon,Kim, Young Gyu
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experimental part
p. 1873 - 1878
(2012/08/07)
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- Kinetic analysis of terminal and unactivated C-H bond oxyfunctionalization in fatty acid methyl esters by monooxygenase-based whole-cell biocatalysis
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The alkane monooxygenase AlkBGT from Pseudomonas putida GPo1 constitutes a versatile enzyme system for the ω-oxyfunctionalization of medium chain-length alkanes. In this study, recombinant Escherichia coli W3110 expressing alkBGT was investigated as whole-cell catalyst for the regioselective biooxidation of fatty acid methyl esters to terminal alcohols. The ω-functionalized products are of general economic interest, serving as building blocks for polymer synthesis. The whole-cell catalysts proved to functionalize fatty acid methyl esters with a medium length alkyl chain specifically at the ω-position. The highest specific hydroxylation activity of 104 U gCDW-1 was obtained with nonanoic acid methyl ester as substrate using resting cells of E. coli W3110 (pBT10). In an optimized set-up, maximal 9-hydroxynonanoic acid methyl ester yields of 95% were achieved. For this specific substrate, apparent whole-cell kinetic parameters were determined with a Vmax of 204±9 U gCDW -1, a substrate uptake constant (KS) of 142±17 μM, and a specificity constant Vmax/KS of 1.4 U g CDW-1 μM-1 for the formation of the terminal alcohol. The same E. coli strain carrying additional alk genes showed a different substrate selectivity. A comparison of biocatalysis with whole cells and enriched enzyme preparations showed that both substrate availability and enzyme specificity control the efficiency of the whole-cell bioconversion of the longer and more hydrophobic substrate dodecanoic acid methyl ester. The efficient coupling of redox cofactor oxidation and product formation, as determined in vitro, combined with the high in vivo activities make E. coli W3110 (pBT10) a promising biocatalyst for the preparative synthesis of terminally functionalized fatty acid methyl esters. Copyright
- Schrewe, Manfred,Magnusson, Anders O.,Willrodt, Christian,Buehler, Bruno,Schmid, Andreas
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experimental part
p. 3485 - 3495
(2012/03/26)
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- Remote supramolecular control of catalyst selectivity in the hydroformylation of alkenes
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In the pocket: The supramolecular interactions between a Rh phosphine catalyst equipped with an anion-binding pocket and alkenes that contain anionic functionalities (see picture) provide an excellent design concept to achieve remote control of the regioselectivity in hydroformylation reactions. The 4-pentenoate and 3-butenylphosphonate, which fit tightly between the Rh center and the pocket, were hydroformylated with unprecedented selectivity.
- Dydio, Pawea,Dzik, Wojciech I.,Lutz, Martin,De-Bruin, Bas,Reek, Joost N. H.
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supporting information; experimental part
p. 396 - 400
(2011/03/16)
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- Process for Preparation of Hexadecyl Cis-9-Tetradecenoate and Hexadecyl Cis-10-Tetradecenoate
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Hexadecyl cis-9-tetradecenoate commonly known as Cetyl myristoleate (CMO) is being used for the treatment of osteoarthritis and other joint inflammatory diseases, cis-9-Tetradecenoic acid (cis-9-myristoleic acid) is the main precursor for the preparation of CMO. As there are limited natural plant sources for cis-9-tetradecenoic acid, the present invention aimed at the synthesis of cis-9-tetradecenoic acid methyl ester from oleic acid methyl ester. As oleic acid is not available in pure form, this has to be isolated from oleic acid-rich oils like olive oil. cis-10-Tetradecenoic acid methyl ester, an isomer of cis-9-tetradecenoic acid was also prepared from undecenoic acid methyl ester, a derivative of castor oil. Undecenoic acid is easily available commercially in pure form. Hexadecyl cis-9-tetradecenoate and hexadecyl c/s-10-tetradecenoate were prepared by enzymatic transesterification of cis-9-tetradecenoic acid methyl ester and cis-10-tetradecenoic acid methyl ester with 1-hexadecanol (cetyl alcohol) respectively. Both the isomers of cetyl myristoleate were evaluated for anti arthritis, blocking inflammation and reduction of adjuvant-induced arthritis in rats.
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Page/Page column 4
(2011/11/12)
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- Mild and selective hydrozirconation of amides to aldehydes using Cp 2Zr(H)Cl: Scope and mechanistic insight
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An investigation of the use of Cp2Zr(H)Cl (Schwartz's reagent) to reduce a variety of amides to the corresponding aldehydes under very mild reaction conditions and in high yields is reported. A range of tertiary amides, including Weinreb's amides, can be converted directly to the corresponding aldehydes with remarkable chemoselectivity. Primary and secondary amides proved to be viable substrates for reduction as well, although the yields were somewhat diminished as compared to the corresponding tertiary amides. Results from NMR experiments suggested the presence of a stable, 18-electron zirconacycle intermediate that presumably affords the aldehyde upon water or silica gel workup. A series of competition experiments revealed a preference of the reagent for substrates in which the lone pair of the nitrogen is electron releasing and thus more delocalized across the amide bond by resonance. This trend accounts for the observed excellent selectivity for tertiary amides versus esters. Experiments regarding the solvent dependence of the reaction suggested a kinetic profile similar to that postulated for the hydrozirconation of alkenes and alkynes. Addition of p-anisidine to the reaction intermediate resulted in the formation of the corresponding imine mimicking the addition of water that forms the aldehyde.
- Spletstoser, Jared T.,White, Jonathan M.,Tunoori, Ashok Rao,Georg, Gunda I.
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p. 3408 - 3419
(2007/10/03)
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- Stille reactions catalytic in tin: A "Sn-F" route for intermolecular and intramolecular couplings
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(Chemical Equation Presented) Polymethylhydrosiloxane (PMHS) made hypercoordinate by KF(aq) allows Me3SnH to be recycled during a Pd(0)-catalyzed hydrostannation/Stille cascade. Starting with a variety of alkynes, in situ vinyltin formation is followed by Stille reaction with aryl, styryl, benzyl, or vinyl electrophiles present in the reaction mixture. Both inter- and intramolecular versions of the process are possible with tin loads of approximately 6 mol %. Regeneration of the organotin hydride is believed to proceed through a Me3SnF intermediate. Given the aggregated nature of organotin fluorides and the ability to use these organotins in substoichiometric quantities, the hazards and purification problems associated with the removal of organotin wastes from reaction mixtures are minimized.
- Gallagher, William P.,Maleczka Jr., Robert E.
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p. 841 - 846
(2007/10/03)
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- A PROCESS FOR PREPARING LONG CHAIN SATURATED OR UNSATURATED OXYGENATED COMPOUNDS
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A process for preparing long chain saturated or unsaturated oxygenated compounds. The process for the preparation of long-chain saturated or unsaturated oxygenated compounds having from 20 to 36 carbon atoms, selected from the group consisting of polycosanoic acids, their alkyl esters, polycosanols and corresponding compounds having an unsaturated hydrocarbon chain comprises the operation of reacting, in accordance with the Wittig or Peterson olefination reaction, a phosphorus ylide RP(Ar)3, wherein R is a saturated or unsaturated hydrocarbon chain containing one or more ethylenic and/or acetylenic unsaturations and Ar is aryl, or the corresponding α-silylcarbanion, respectively, with an n-alkanoic acid, formylated in the terminal position, or with its corresponding alkyl ester.
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- Conversion of (Z)-1,4-dihydroxyalk-2-enes into 2,5-dihydrofurans and of alkane-1,4-diols into tetrahydrofurans via acid-catalysed cyclisation of the monoisoureas formed by their copper(I)-mediated reactions with dicyclohexylcarbodiimide
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(Z)-1,4-dihydroxyalk-2-enes were converted into 2,5-dihydrofurans and alkane-1,4-diols were converted into tetrahydrofurans via acid-catalysed cyclisation of the monoisoureas. The reaction involved protonation of the carbodiimide by acidic phenol followed by reaction with alkanol. Pd/CaCo3-quinoline catalyst system was employed in the presence of a little triethylamine to overcome partial hydrogenolysis.
- Duffy, Michael G.,Grayson, David H.
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p. 1555 - 1563
(2007/10/03)
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- New Pd-catalyzed selective reduction of carboxylic acids to aldehydes.
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A catalyst generated in situ from palladium acetate and tricyclohexylphosphine efficiently catalyzes the reduction of carboxylic acids with sodium hypophosphite in the presence of pivalic anhydride to give aldehydes with high selectivity. The low cost and convenient handling of the reagents makes this process a valuable alternative to hydrogenations and metal hydride reductions.
- Goossen, Lukas J,Ghosh, Keya
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p. 836 - 837
(2007/10/03)
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- Ruthenium-catalyzed oxidative cleavage of olefins to aldehydes
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Three oxidation protocols have been developed to cleave olefins to carbonyl compounds with ruthenium trichloride as catalyst (3.5 mol %). These methods convert olefins that are not fully substituted to aldehydes rather than carboxylic acids. While aryl olefins were cleaved to aromatic aldehydes in excellent yields by using the system of RuCl3-Oxone-NaHCO3 in CH3CN-H2O (1.5:1), aliphatic olefins were converted into alkyl aldehydes with RuCl3-NaIO4 in 1,2-dichloroethane-H2O (1:1) in good to excellent yields. It is noteworthy that terminal aliphatic olefins were cleaved to the corresponding aldehydes in excellent yields by using RuCl3-NaIO4 in CH3CN-H2O (6:1).
- Yang,Zhang
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p. 4814 - 4818
(2007/10/03)
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- A new family of polymerizable lyotropic liquid crystals: Control of feature size in cross-linked inverted hexagonal assemblies via monomer structure
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An efficient and versatile synthesis of a series of polymerizable amphiphilic mesogens that affords control over tail length and position of the polymerizable group is described. The synthesis employs a novel and facile method of preparing styrene ethers. The monomers are sodium salts of styrene ether-modified fatty acids that can be used to form cross-linkable inverted hexagonal (HII) lyotropic liquid crystal (LLC) phases at ambient temperature with controllable nanometer-scale dimensions. Examination of a series of regioisomers with the same alkyl chain length but with the styrene ether group at different locations along the chain revealed that the position of the styrene ether has a profound effect on the dimensions of the resulting HII phase at a fixed temperature and composition. Increasing overall monomer tail length also has a significant, although smaller, effect on the unit cell dimensions of the LLC phase. By controlling the structure of the LLC monomer in this manner, cross-linked HII phases with interchannel distances (ICD) ranging from 29 to 54 A can be obtained. Furthermore, changing the counterion from Na+ to tetraalkylammonium ions leads to further expansion of the HII unit cell to a maximum ICD of 65 A, as well as to the production of a lamellar phase. Use of these monomers affords a new and unparalleled degree of control over phase structure and dimensions for the production of nanostructured organic materials.
- Reppy,Gray,Pindzola,Smithers,Gin
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p. 363 - 371
(2007/10/03)
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- Stille couplings catalytic in tin: a "Sn-F" approach.
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A new tin recycling method for Stille couplings catalytic in tin is reported. PMHS made hypercoordinate by KF((aq)) allows Me(3)SnH to be efficiently recycled during a Pd(0)-catalyzed hydrostannation/Stille cascade. Relative to previously disclosed protoc
- Maleczka Jr.,Gallagher
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p. 4173 - 4176
(2007/10/03)
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- Methylenephenylsulfone appended acetals and ketals: New class of carbonyl protective groups cleavable by DBU
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3-phenylsulfonyl 1,2 propane diol, readily obtainable by dihydroxylation of commercially available allylphenylsulfone, acts as an efficient and new protection reagent for both aldehydes and ketones. This protective group is elegantly removed by use of 1,8-diazabicyclo[5.4.0]-7-undecene (DBU), under nonaqueous conditions.
- Chandrasekhar,Sarkar, Sanjita
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p. 2401 - 2404
(2007/10/03)
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- Synthesis and nematocidal activity of aralkyl- and aralkenylamides related to piperamide on second-stage larvae of Toxocara canis
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Seventy-nine aralkyl- and aralkenylamides related to piperamides were synthesized and their nematocidal activity against second-stage larvae of dog roundworm, Toxocara canis, was examined. The activity was greatly dependent on the alkyl chain length and the nature of the amine moiety, but was scarcely affected by the presence or absence of double bond(s) in the chain. The alkyl chain lengths which showed the strongest activity in a series of homologues were m=11 for the pyrrolidine amides and m=13 for the N- methylpiperazine amides. Although piperamides (3,4-methylenedioxyphenyl homologues) showed the strongest activity among the homologues tested, methoxy substituent(s) on the aromatic ring did not have much effect on the activity. However, conversion of the methoxy group to a hydroxy group greatly decreased the activity and shortened the chain length giving the strongest activity. Calculated log P values of non-phenolic aryl-piperamides fell in the range from 3.5 to 4.5, whereas those of hydroxyphenyl-piperamides were smaller, suggesting that different mechanisms are involved in the nematocidal activity of phenolic and non-phenolic compounds.
- Kiuchi, Fumiyuki,Nakamura, Norio,Saito, Makiko,Komagome, Kazue,Hiramatsu, Hirokuni,Takimoto, Noriaki,Akao, Nobuaki,Kondo, Kaoru,Tsuda, Yoshisuke
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p. 685 - 696
(2007/10/03)
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- A mild and convenient deprotection of 4-phenyl 1,3-dioxolane derivatives under catalytic hydrogenation
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A new procedure for deprotection of 4-phenyl 1,3-dioxolanes to liberate free carbonyl compound under catalytic hydrogenation conditions is described.
- Chandrasekhar,Muralidhar,Sarkar, Sanjita
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p. 2691 - 2694
(2007/10/03)
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- Synthesis of Very Long Fatty Acid Methyl Esters
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Phosphoranes, produced by treating alkyltriphenylphosphonium bromides with lithium hexamethyldisilazide, reacted with ω-oxo esters to give modest yields of the corresponding methyl cis-alkenoates.By an alternative method, treatment of ω-iodo esters with the complexes formed from reactions of alkylcopper(I) and Grignard reagents gave methyl alkanoates, cis-alkenoates, and methylene-interrupted cis,cis-alka-dienoates and cis,cis,cis-trienoates.The stereochemical integrity of the esters was determined by 13C NMR spectroscopy.
- Kling, Marcel R.,Easton, Christopher J.,Poulos, Alf
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p. 1183 - 1190
(2007/10/02)
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- SYNTHESIS OF PHEROMONES, IV. CHEMISTRY OF THE WITTIG REACTION, I. EFFECTS OF REACTION CONDITIONS ON THE STEREOSELECTIVITY AND YIELD OF THE WITTIG REACTION
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The reactions of nonstabilized triphenylphosphorus ylides with aldehydes have been studied in detail.The stereochemistry and yields of the alkene products are highly dependent upon base used for the generation of the ylide, the solvent and reaction temperature.The synthesis of sex pheromone components by Wittig reaction are also described.
- Vinczer, Peter,Juvancz, Zoltan,Novak, Lajos,Szantay, Csaba
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p. 797 - 820
(2007/10/02)
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- Synthese de lactones a cycle moyen: Application a la synthese du pentadecanolide-15 et du phoracantholide I
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Medium ring size lactones can be prepared from bifunctional commercial starting compounds in high yields, using a few step sequence.Lactonisation is obtained by cyclization of the free ω-hydroxyacids or by the cyclization of ω-hydroxyacids having the hydroxy and carboxy group protected.
- Cossy, Janine,Pete, Jean-Pierre
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p. 989 - 994
(2007/10/02)
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- ISOLATION, STRUCTURE AND SYNTHESIS OF MAESANIN, A HOST DEFENSE STIMULANT FROM AN AFRICAN MEDICINAL PLANT MAESA LANCEOLATE
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The isolation, characterization and an efficient synthesis of maesanin 1, a host defense stimulant isolated from an African medicinal plant Maesa lanceolate, is reported.
- Kubo, Isao,Kim, Mujo,Ganjian, Iraj,Kamikawa, Tadao,Yamagiwa, Yoshiro
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p. 2653 - 2660
(2007/10/02)
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- A New Synthesis of 8-(ω-Carbomethoxyhexyl)-11-hydroxycyclopent-8(12)-ene-9-one, a Versatile Prostaglandin Intermediate
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8-(ω-Carbomethoxyhexyl)-11-hydroxycyclopent-8(12)-ene-9-one (V), a versatile prostaglandin synthon, has been synthesised starting from easily accesible undecylenic acid (VI).The synthesis involves preparation of dihydroxy undecanoic acid (IX) and its methyl ester (X), methyl 9-formylnonanoate (XI), the monoester (XII) and the corresponding unsaturated acid (XIII), γ-lactone (XIV), cyclopentenone acid (XV) and finally the all important PG-intermediate 2-(ω-carbomethoxyhexyl)cyclopentenone (IV).Its reduction with sodium borohydride gives the saturated alcohol (XVI), which via oxidation with Jones' reagent and bromination-dehydrobromination sequence could be converted back to IV.However, IV, on reduction with aluminium isopropoxide gives the allylic alcohol (XXIII), which is converted via acetylation into the acetate (XXIV).Subsequent oxidation of acetate (XXIV) with t-butyl chromate yields the keto-acetate (XXV), which on reduction with aluminium isopropoxide furnishes the hydroxy acetates (XXXII).The hydroxyl group in XXXII is protected as tetrahydropyranyloxy derivative (XXXIII).Hydrolysis of XXXIII with alkali leads to the hydroxy acids (XXXIV).Oxidation of XXXIV with Jones' reagent at low temperature for a short period yields the keto-acid (XXXV), which is esterified to give the ester (XXXVI).Finally, removal of the pyranyloxy group from XXXVI furnishes the versatile synthon (V), identical with the sample prepared by a known procedure.
- Thakur, S. B.,Jadhav, K. S.,Bhattacharyya, S. C.
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p. 675 - 683
(2007/10/02)
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- Model Studies on the Synthesis of Medium-sized and Large Carbocycles using the Ireland Enolate Claisen Rearrangement
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Model studies have shown that the enolate Claisen rearrangement, a modification (developed by R.E.Ireland et al.) of the original Claisen rearrangement, can successfully be applied to the elaboration of medium-sized and large carbocycles from O-silyl enolates of suitable unsaturated macrolides (Scheme).The rearrangements are largely non-stereoselective, a fact which can be rationalised in terms of the intermediacy of both chair- and boat-like transition states and possibly because, in some cases, both the (E)- and (Z)-enolate of the macrolides are involved.
- Cameron, Andrew G.,Knight, David W.
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p. 161 - 168
(2007/10/02)
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- PROSTANOIDS. XII. SYNTHESIS OF THE KEY SYNTHONS AND SOME α-HOMOANALOGS OF 11-DEOXYPROSTAGLANDIN E1
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The cuprate synthesis of the di-, tri,- tetra,- and pentahomoanalogs of 11-deoxyprostaglandin E1 was realized from the corresponding α-homo-2-(butoxycarbonylalkenyl)-2-cyclopenten-1-ones.The latter were obtained by the condensation of 1-morpholinocyclopentene with α,ω-aldehydo esters, prepared by ozonolytic cleavage of cyclic olefins, E,E,E-cyclododecatriene, and undecylenic acid.
- Tolstikov, G. A.,Miftakhov, M. S.,Valeev, F. A.,Akhmetvaleev, R. R.,Khalilov, L. M.,Panasenko, A. A:
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- SYNTHESIS OF SELENOACETALS
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This paper reports our results concerning the syntheses of various bis(alkylseleno)alkanes and some of their arylseleno analogues by different methods.The scope and limitation of each of them are presented.
- Clarembeau, M.,Cravador, A.,Dumont, W.,Hevesi, L,Krief, A.,et al.
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p. 4793 - 4812
(2007/10/02)
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- A NOVEL STEREOCONTROLLED SYNTHESIS OF (Z,Z)-3,13-OCTADECDIEN-1-YL ACETATE, THE SEX PHEROMONE OF SYNANTHEDON SPECIES
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Starting from 10-undecenoic acid, a stereocontrolled synthesis of (Z,Z)-3,13-octadecadien-1-yl acetate with high sterochemical purity was achieved by the use of Wittig-olefinations for the introductions of (Z)-double bonds.
- Vinczer, Peter,Baan, Gabor,Novak, Lajos,Szantay, Csaba
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p. 2701 - 2704
(2007/10/02)
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- ISOLATION, STRUCTURE AND SYNTHESIS OF MAESANIN, A HOST DEFENSE STIMULANT FROM AN AFRICAN MEDICINAL PLANT MAESA LANCEOLATA
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The isolation, characterization and an efficient synthesis of maesanin 1, a host defense stimulant isolated from an African medicinal plant Maesa lanceolata is reported.
- Kubo, Isao,Kamikawa, Tadao,Miura, Iwao
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p. 3825 - 3828
(2007/10/02)
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- Stereochemistry of Deconjugative Alkylation of Ester Dienolates. Stereospecific Total Synthesis of the Litsenolides
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Deconjugative protonations, alkylations, and aldol condensations of the dienolates from (Z)-2-alkenoates give the corresponding (E)-3-enoate products, whereas dienolates from (E)-2-enoates give mainly the (Z)-3-enoate products.These generalizations are exploited in stereospecific total syntheses of litsenolides A2, B2, and C2.
- Kende, Andrew S.,Toder, Bruce H.
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p. 163 - 167
(2007/10/02)
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