- STUDIES ON THE IDENTIFICATION AND SYNTHESES OF INSECT PHEROMONES XXI. STEREOSELECTIVE SYNTHESIS OF ALL THE POSSIBLE OPTICAL ISOMERS OF THE MOSQUITO OVIPOSITION ATTRACTANT PHEROMONE.
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All the four optical isomers of the oviposition attractant pheromone of the mosquito Culex pipiens fatigans were synthetized via Sharpless asymmetric epoxidation.
- Guo-qiang, Lin,Hai-jian, Xu,Bi-chi, Wu,Guong-zhong, Guo,Wei-shan, Zhou
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- Enantioselective synthesis of four isomers of 3-hydroxy-4- methyltetradecanoic acid, the constituent of antifungal cyclodepsipeptides W493 A and B
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Four possible stereoisomers of 3-hydroxy-4-methyltetradecanoic acid were enantioselectively synthesized by using Sharpless epoxidation and a subsequent epoxide-ring opening reaction with trimethylaluminum as the key steps. The absolute configuration of the β-oxyacid component of antifungal cyclodepsipeptides W493 A and B was consequently determined as 3S,4R.
- Nihei, Ken-Ichi,Hashimoto, Kimiko,Miyairi, Kazuo,Okuno, Toshikatsu
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- Bulky Cyclometalated Ruthenium Nitrates for Challenging Z-Selective Metathesis: Efficient One-Step Access to α-Oxygenated Z-Olefins from Acrylates and Allyl Alcohols
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α-Oxygenated Z-olefins are ubiquitous in biologically active molecules and serve as versatile handles for organic synthesis, but their syntheses are often tedious and less selective. Here we report the efficient Z-selective metathesis of various terminal
- Gan, Quan,Grubbs, Robert H.,Ko, Jeong Hoon,Samkian, Adrian E.,Xu, Yan
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supporting information
(2021/12/10)
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- Synergistic Relay Reactions To Achieve Redox-Neutral α-Alkylations of Olefinic Alcohols with Ruthenium(II) Catalysis
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Herein, we report a ruthenium-catalyzed redox-neutral α-alkylation of unsaturated alcohols based on a synergistic relay process involving olefin isomerization (chain walking) and umpolung hydrazone addition, which takes advantage of the interaction between the two rather inefficient individual reaction steps to enable an efficient overall process. This transformation shows the compatibility of hydrazone-type “carbanions” and active protons in a one-pot reaction, and at the same time achieves the first Grignard-type nucleophilic addition using olefinic alcohols as latent carbonyl groups, providing a higher yield of the corresponding secondary alcohol than the classical hydrazone addition to aldehydes does. A broad scope of unsaturated alcohols and hydrazones, including some complex structures, can be successfully employed in this reaction, which shows the versatility of this approach and its suitability as an alternative, efficient means for the generation of secondary and tertiary alcohols.
- Kan, Jian,Li, Chao-Jun,Li, Chen-Chen,Li, Jianbin,Lv, Leiyang,Qiu, Zihang
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supporting information
p. 4544 - 4549
(2020/02/04)
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- New strategy for production of primary alcohols from aliphatic olefins by tandem cross-metathesis/hydrogenation
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Primary alcohols are widely used in industry as solvents and precursors of detergents. The classic methods for hydration of terminal alkenes always produce the Markovnikov products. Herein, we reported a reliable approach to produce primary alcohols from terminal alkenes combining with biomass-derived allyl alcohol by tandem cross-metathesis/hydrogenation. A series of primary alcohol with different chain lengths was successfully produced in high yields (ca. 90percent). Computational studies revealed that self-metathesis and hydrogenation of substrates are accessible but much slower than cross-metathesis. This new methodology represents a unique alternative to primary alcohols from terminal alkenes.
- Jia, Ruilong,Zuo, Zhijun,Li, Xu,Liu, Lei,Dong, Jinxiang
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supporting information
p. 1525 - 1529
(2019/11/11)
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- Copper-Catalyzed Perfluoroalkylation of Allyl Phosphates with Stable Perfluoroalkylzinc Reagents
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A general and practical method for copper-catalyzed cross-coupling of allyl phosphates with stable perfluoroalkylzinc reagents has been developed. The reaction proceeds under mild reaction conditions with high efficiency, good functional group tolerance, and high regio- A nd stereoselectivities and provides general, straightforward, and useful access to allyl-perfluoroalkyl compounds. Preliminary mechanistic studies reveal that the allyl copper intermediate may be involved in the catalytic cycle.
- Liu, Lihua,Bao, Xifei,Xiao, Hua,Li, Junlan,Ye, Feifan,Wang, Chaoqin,Cai, Qinhua,Fan, Shilu
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p. 423 - 434
(2019/01/08)
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- In Situ Generation of Ru-Based Metathesis Catalyst. A Systematic Study
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A systematic study for the in situ generation of Ru-based metathesis catalysts was described. Assembly of commercially available and inexpensive reagents [Ru(p-cymene)Cl2]2, SIPr·HCl, and n-BuLi led to the formation of 18 electron arene-ruthenium complexes that, in the presence of additives such as alkynes, cyclopropenes, and diazoesters, generated highly selective and efficient catalytic systems applicable to a variety of olefin metathesis transformations. Notably, we were able to achieve a productive TON of 4500 for the self-metathesis of methyl oleate, a reaction which could be easily upscaled to 2 kg.
- Müller, Daniel S.,Raoul, Yann,Le N?tre, Jér?me,Baslé, Olivier,Mauduit, Marc
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p. 3511 - 3518
(2019/04/01)
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- Synthetic method for American white moth sex pheromone
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The invention provides a synthetic method for an American white moth sex pheromone. 2-propargyl alcohol which is cheap and easy to obtain is used as a raw material, the American white moth sex pheromone a (9S,10R)-9,10-epoxy-(3Z,6Z)-3,6-heneicosadiene is synthesized in a high enantioselectivity and high yield, and enantiomer excess e.e. achieves 99% or more. According to the synthetic method for the American white moth sex pheromone, the production process is safer, the costs are low, the selectivity is higher, and the synthetic method is more energy-saving and environmentally friendly.
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Paragraph 0019; 0020; 0023; 0025
(2018/04/01)
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- Stereoretentive Olefin Metathesis Made Easy: In Situ Generation of Highly Selective Ruthenium Catalysts from Commercial Starting Materials
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The in situ preparation of highly stereoretentive ruthenium-based metathesis catalysts is reported. This approach completely avoids the isolation of intermediates and air-sensitive catalysts, thus allowing for the rapid access and evaluation of numerous dithiolate Ru catalysts. A procedure was established to perform cross-metathesis reactions without the use of a glovebox, and on a small scale even Schlenk techniques are not required. Consequently, the chemistry displayed in this report is available to every practicing organic chemist and presents a powerful approach for the identification of new stereoretentive catalysts.
- Müller, Daniel S.,Curbet, Idriss,Raoul, Yann,Le N?tre, Jér?me,Baslé, Olivier,Mauduit, Marc
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supporting information
p. 6822 - 6826
(2018/10/31)
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- Synthesis and Application of Stereoretentive Ruthenium Catalysts on the Basis of the M7 and the Ru-Benzylidene-Oxazinone Design
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A series of new stereoretentive ruthenium catalysts bearing the dithiocatecholate ligand was synthesiszed on the basis of the M7 and Ru-benzylidene-oxazinone design. The activity of the catalysts was tested in ring-opening cross-metathesis reactions, ring
- Dumas, Adrien,Müller, Daniel S.,Curbet, Idriss,Toupet, Lo?c,Rouen, Mathieu,Baslé, Olivier,Mauduit, Marc
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supporting information
p. 829 - 834
(2018/03/21)
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- High-value alcohols and higher-oxidation-state compounds by catalytic Z-selective cross-metathesis
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Olefin metathesis catalysts provide access to molecules that are indispensable to physicians and researchers in the life sciences. A persisting problem, however, is the dearth of chemical transformations that directly generate acyclic Z allylic alcohols, including products that contain a hindered neighbouring substituent or reactive functional units such as a phenol, an aldehyde, or a carboxylic acid. Here we present an electronically modified ruthenium-disulfide catalyst that is effective in generating such high-value compounds by cross-metathesis. The ruthenium complex is prepared from a commercially available precursor and an easily generated air-stable zinc catechothiolate. Transformations typically proceed with 5.0 mole per cent of the complex and an inexpensive reaction partner in 4-8 hours under ambient conditions; products are obtained in up to 80 per cent yield and 98:2 Z:E diastereoselectivity. The use of this catalyst is demonstrated in the synthesis of the naturally occurring anti-tumour agent neopeltolide and in a single-step stereoselective gram-scale conversion of a renewable feedstock (oleic acid) to an anti-fungal agent. In this conversion, the new catalyst promotes cross-metathesis more efficiently than the commonly used dichloro-ruthenium complexes, indicating that its utility may extend beyond Z-selective processes.
- Koh, Ming Joo,Khan, R. Kashif M.,Torker, Sebastian,Yu, Miao,Mikus, Malte S.,Hoveyda, Amir H.
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p. 181 - 186
(2015/03/30)
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- CATALYSTS FOR EFFICIENT Z-SELECTIVE METATHESIS
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The present application provides, among other things, compounds and methods for metathesis reactions. In some embodiments, provided compounds promote highly efficient and highly Z-selective metathesis. In some embodiments, provided compounds and methods are particularly useful for producing allyl alcohols. In some embodiments, provided compounds have the structure of formula I. In some embodiments, provided compounds comprise ruthenium, and a ligand bonded to ruthenium through a sulfur atom.
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Paragraph 00643-00645
(2015/01/09)
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- Enantiomer and conformer recognition of (+) and (-)-disparlure and their analogs by the pheromone binding proteins of the gypsy moth, Lymantria dispar
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Adult female gypsy moths produce a sex pheromone (+)-(7R,8S)-2-methyl-7,8- epoxyoctadecane, (+)-disparlure, to attract male gypsy moths. To better understand the recognition of (+)-disparlure by the male's olfactory system, we synthesized racemic and enantiopure oxa and thia analogs of (+)-disparlure (ee > 98%). Ab initio calculations of the conformeric landscapes around the dihedral angles C5-6-7-8 and C7-8-9-10 of (+)-disparlure and corresponding dihedral angles of analogs revealed that introduction of the heteroatom changes the conformeric landscape around these important epitopes. The energy difference between HOMO and LUMO decreased after oxygen or sulfur was introduced into the backbone. Consistent with this, an enhancement of binding affinity between sulfur analogs and the pheromone-binding proteins (PBPs) was observed in vitro. Docking of the pheromone and analogs onto models of the two known PBPs of the gypsy moth revealed that the internal binding pocket of PBP1 showed higher selectivity than that of PBP2, consistent with in vitro binding assays. Further energy analysis revealed that enantiomers adopted different conformations with different energies when docked in the internal binding pocket of PBPs, resulting in enantiomer discrimination of PBPs towards disparlure and its analogs.
- Yu, Yang,Plettner, Erika
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supporting information
p. 1811 - 1822
(2013/04/24)
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- Asymmetric synthesis of both enantiomers of disparlure
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Starting from propargyl alcohol (12), and on the basis of Zhou's modified Sharpless asymmetric epoxidation, the sex pheromone of the Gypsy moth, disparlure (+)-8 and its enantiomer (-)-8 have been synthesized, each in six steps, with overall yields of 29% for (+)-8 and 27% for (-)-8 (ee>98%). The use of the sequential coupling tactic renders the method flexible, which is applicable to the synthesis of other cis-epoxy pheromones. Copyright
- Wang, Zhigang,Zheng, Jianfeng,Huang, Peiqiang
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experimental part
p. 23 - 28
(2012/03/10)
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- Toward a modular, bidirectional synthesis of (-)-mucocin
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A convergent stereoselective synthesis of the C13-C34 fragment of (-)-mucocin is described. The salient features include (a) the bidirectional synthesis of the C-2 symmetric C13-C21 subunit, (b) regio- and stereoselective preparation of a 1,3-diol derivative from a diene activated by NBS via intramolecular nucleophilic sulfinyl group participation, (c) utilizing the self-metathesis reaction to prepare a functionalized C10 alkene, and (d) regio- and stereoselective intermolecular epoxide opening to construct the ether bond between C20 and C24. An organocatalytic α-hydoxylation has been employed to create the C4 stereogenic center of C1-C12 subunit. Attempted union of the two subunits utilizing the B-alkyl Suzuki coupling did not succeed.
- Raghavan, Sadagopan,Subramanian, S. Ganapathy
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experimental part
p. 7529 - 7539
(2011/10/12)
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- Structure-Activity relationship of aliphatic compounds for nematicidal activity against pine wood nematode (Bursaphelenchus xylophilus)
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Nematicidal activity of aliphatic compounds was tested to determine a structure-activity relationship. There was a significant difference in nematicidal activity among functional groups. In a test with alkanols and 2E-alkenols, compounds with C8-C11 chain length showed 100% nematicidal activity against pine wood nematode, Bursaphelenchus xylophilus, at 0.5 mg/mL concentration. C6-C10 2E-alkenals exhibited >95% nematicidal activity, but the other compounds with C 11-C14 chain length showed weak activity. Nematicidal activity of alkyl acetates with C7-C11 chain length was strong. Compounds belonging to hydrocarbons, alkanals, and alkanoic acetates showed weak activity at 0.5 mg/mL concentration. Nematicidal activity of active compounds was determined at lower concentrations. At 0.25 mg/mL concentration, whole compounds except C8 alkanol, C8 2E-alkenol, and C7 alkanoic acid showed >80% nematicidal activity. C 9-C11 alkanols, C10-C11 2E-alkenols, C8-C9 2E-alkenals, and C9-C10 alkanoic acids showed >80% nematicidal activity at 0.125 mg/mL concentration. Only C11 alkanol exhibited strong nematicidal activity at 0.0625 mg/mL concentration, the lowest concentration that was tested. 2010 American Chemical Society.
- Seo, Seon-M.I.,Junheon, Kim,Eunae, Kim,Park, Hye-M.I.,Kim, Young-Joon,Park, I.L.-Kwon
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experimental part
p. 1823 - 1827
(2010/09/09)
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- Cobalt-catalyzed trimethylsilylmethylmagnesium-promoted radical alkenylation of alkyl halides: A complement to the Heck reaction
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A cobalt complex, [CoCl2(dpph)] (DPPH = [1,6- bis(diphenylphosphino)hexane]), catalyzes an intermolecular styrylation reaction of alkyl halides in the presence of Me3SiCH2MgCl in ether to yield β-alkylstyrenes. A variety of alkyl halides including alkyl chlorides can participate in the styrylation. A radical mechanism is strongly suggested for the styrylation reaction. The sequential isomerization/styrylation reactions of cyclopropylmethyl bromide and 6-bromo-1-hexene provide evidence of the radical mechanism. Crystallographic and spectroscopic investigations on cobalt complexes reveal that the reaction would begin with single electron transfer from an electron-rich (diphosphine)bis(trimethylsilylmethyl)cobalt(II) complex followed by reductive elimination to yield 1,2-bis(trimethylsilyl)ethane and a (diphosphine)cobalt(I) complex. The combination of [CoCl 2(dppb)] (DPPB = [1,4-bis(diphenylphosphino)butane]) catalyst and Me3SiCH2-MgCl induces intramolecular Heck-type cyclization reactions of 6-halo-1-hexenes via a radical process. On the other hand, the intramolecular cyclization of the prenyl ether of 2-iodophenol would proceed in a fashion similar to the conventional palladium-catalyzed transformation. The nonradical oxidative addition of carbon(sp2)-halogen bonds to cobalt is separately verified by a cobalt-catalyzed cross-coupling reaction of alkenyl halides with Me3SiCH2MgCl with retention of configuration of the starting vinyl halides. The cobalt-catalyzed intermolecular radical styrylation reaction of alkyl halides is applied to stereoselective variants. Styrylations of 1-alkoxy-2-bromocyclopentane derivatives provide trans-1-alkoxy-2-styrylcyclopentane skeletons, one of which is optically pure.
- Affo, Walter,Ohmiya, Hirohisa,Fujioka, Takuma,Ikeda, Yousuke,Nakamura, Tomoaki,Yorimitsu, Hideki,Oshima, Koichiro,Imamura, Yuki,Mizuta, Tsutomu,Miyoshi, Katsuhiko
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p. 8068 - 8077
(2007/10/03)
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- Synthesis of disparlure analogues, using resolution on microcrystalline cellulose triacetate-I
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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
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p. 3773 - 3784
(2007/10/03)
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- Scope and limitations of lithium-ethylenediamine-THF-mediated cleavage at the α-position of aromatics: Deprotection of aryl methyl ethers and benzyl ethers under mild conditions
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The scope and limitation of lithium-ethylenediamine-THF-mediated reductive bond cleavage at the α-position of aromatics were examined. Very mild conditions such as lithium metal (5 equiv) and ethylenediamine (7 equiv) in oxygen-free THF were quite effective for the demethylation of aromatic ethers even at as low as -10°C. Allyl benzyl ethers were also deprotected under these conditions with very little change of the allylic alcohol moiety. Through this study, 2,6-dimethylbenzyl (m-xylylmethyl, MXM) group was developed as an alternative of benzyl group, which is readily cleavable under the above mentioned reductive conditions.
- Shindo, Takeyuki,Fukuyama, Yasuaki,Sugai, Takeshi
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p. 692 - 700
(2007/10/03)
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- Rubrenolide, total synthesis and revision of its reported stereochemical structure
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In this paper the synthesis of the natural product rubrenolide is presented. Due to an error in the original proposed stereochemical structure of rubrenolide, the synthesis was not straightforward. Application of the photo-induced rearrangement of an appropriate epoxy diazomethyl ketone gave access to the precursor lactone with an ee of 91%. Coupling of this lactone with (4S)-2,2-dimethyl-[1,3]-dioxolane-4-carbaldehyde gave, after some additional steps, the final product that was identical with an authentic sample of the natural product.
- Thijs,Zwanenburg
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p. 5237 - 5252
(2007/10/03)
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- IMMUNOMODULATORY COMPOUNDS AND METHODS OF USE THEREOF
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The present invention is directed to methods of treating diseases and disorders related to immune responses by administering one or more immunomodulatory compounds. In particular, the invention is directed to methods of stimulating and reducing immune responses, treating autoimmune conditions, treating allergic reactions and asthma, and preventing ischemic damage and asthma by administering one or more immunomodulatory compounds.
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- Differential cleavage of arylmethyl ethers: Reactivity of 2,6-dimethoxybenzyl ethers
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CrCl2/LiI selectively cleave benzyl ethers and methoxy-substituted benzyl ethers (see scheme) in the order: C6H5CH2OR 6H4CH2OR 2C6H3CH2OR 2C6H3CH2OR. In contrast, C6H5CH2OR is more readily cleaved than 2,6-(MeO)2C6H3CH2OR during catalytic hydrogenolysis while 3,4-(MeO)2C6H3CH2OR is cleaved faster than 2,6-(MeO)2C6H3CH2OR with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ).
- Falck,Barma,Baati, Rachid,Mioskowski, Charles
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p. 1281 - 1283
(2007/10/03)
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- A simple synthetic method for chiral 1,2-epoxides and the total synthesis of a chiral pheromone epoxide
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Chiral 1,2-epoxyalkan-3-ol tosyl esters 4a-h were successfully synthesized from alkynols or allyl chlorides in three steps using Sharpless AD reaction as a key step in good yields. The chiral insect pheromone epoxide (6Z,9S,10R)-9,10-epoxyhenicos-6-ene 9 was thus smoothly synthesized from the corresponding key intermediate 4g.
- Zhang, Zhi-Bo,Wang, Zhi-Min,Wang, Yu-Xiu,Liu, Huan-Quan,Lei, Gui-Xin,Shi, Min
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- Total synthesis and biological evaluation of glycolipids plakosides A, B, and their analogs
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The total synthesis of plakosides A (1) and B (2), and their designed analogs 3-10 was accomplished. The convergent strategy employed involved construction of the individual building blocks employing the Sharpless asymmetric dihydroxylation and the Charette asymmetric cyclopropanation reactions to introduce the desired configuration, followed by their couplings and final elaboration. Thus, key intermediates 12-14 were prepared in their optically active forms and joined through a glycosidation reaction and amide-bond formation to yield the target molecules after appropriate elaboration and final deprotection. The synthesized compounds 1-10 were evaluated for their immunosuppressive properties in vitro and found to be only modestly active.
- Nicolaou, Kyriacos C.,Li, Jim,Zenke, Gerhard
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p. 1977 - 2006
(2007/10/03)
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- A facile synthetic method for chiral 1,2-epoxides and the total synthesis of chiral pheromone epoxides
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Chiral 1,2-epoxy-3-alkanol tosylates were successfully synthesized from alkynols in three steps using the Sharpless AD reaction as a key step in good yields. Two chiral insect pheromone epoxides were smoothly obtained from the corresponding key intermediate.
- Zhang, Zhi-Bo,Wang, Zhi-Min,Wang, Yu-Xiu,Liu, Huan-Quan,Lei, Gui-Xin,Shi, Min
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p. 837 - 840
(2007/10/03)
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- (Carboxyalkyl)benzyl propargyl ethers as selective inhibitors of leukocyte-type 12-lipoxygenases
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A series of (carboxyalkyl)benzyl propargyl ethers was synthesized and tested as inhibitors of 12-lipoxygenase (12-LO) from porcine leukocyte cytosol. Optimum activity was displayed by 3-[4-[(2- tridecynyloxy)methyl]phenyl]propanoic acid. Altering the length of the alkyl side chain attached to the acetylenic group reduced activity. Changing the substitution pattern in the (carboxyalkyl)benzyl group from para to meta or ortho also reduced activity. Analogs in which the triple bond was replaced by a double bond or an allene displayed reduced activity, whereas fully saturated analogs were inactive. High concentrations (10 μM) of the most potent acetylenic (carboxylalkyl)benzyl ethers did not inhibit human platelet 12-LO, human neutrophil 5-LO, rabbit reticulocyte 15-LO, or soybean 15-LO. Thus, this class of compounds represents the first example of isoform specific LO inhibitors.
- Gorins, Gilles,Kuhnert, Lethea,Johnson, Carl R.,Marnett, Lawrence J.
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p. 4871 - 4878
(2007/10/03)
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- Spicamycin derivatives and their use as anticancer agents
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Spicamycin derivative represented by the formula (I) or a salt thereof: STR1 wherein R represents specific diverse substituents, for example, a linear alkadienyl having from 11 to 13 carbon atoms, and R1 and R2 respectively represent H or OH. Examples of specific compounds are 6-[4'-N-(N'-trans,trans 2,4-tridecadienoylglycyl)spicaminyl-amino]purine, and 6-[4'-N-(N'-trans,trans-2,4 dodecadienyoly glycyl) spicaminyl-amino]purine. Comopunds according to this invention are useful as a pharmaceutical for inhibition of a tumor, for example, human colon cancer.
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- ARYL ALIPHATIC ACIDS
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Novel aryl aliphatic acids or derivatives thereof of the general formula R-(Cx-Cy)-(CmH2m)-G-C(R1)2-Ar-(CnH2n)-COOR2 are described which exhibit inhibiting activity against 12-lipoxygenase. The compounds are characterized by having a low level of toxicity. Also included are salts and esters of the aliphatic acids
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- The reaction of trimethylsilyl ethylene oxide with α-sulfonyl anions and α,α-sulfonyl dianions. A method for stereocontrolled synthesis of (E)- and (Z)-allylic alcohols
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Trimethylsilyl ethylene oxide has been shown to react with α-sulfonyl carbanions generated from representative primary alkyl phenyl sulfones to give the corresponding O-trimethylsilyl allylic alcohols, with higher selectivity for (Z)-isomers.The reaction proceeds by attachment of the nucleophile to the α-position of the α,β-epoxyalkylsilane followed by a carbon-to-oxygen shift of the trimethylsilyl group and expulsion of the benzenosulfonyl anion.The reaction of trimethylsilyl ethylene oxide with α,α-sulfonyl dianions followed by partial protonation of the immediate adducts affords O-trimethylsilyl allylic alcohols, mainly (E)-isomers.The reaction of trimethylsilyl ethylene oxide with α-sulfonyl carbanions generated from secondary alkyl phenyl sulfones affords α-trimethylsilyl carbinols as the only or predominant product.In this case the attachment of the nucleophile takes place at the β-position of the α,β-epoxyalkylsilane.The origin of the regio- and stereo-selectivity in reactions of sulfonyl carbanions with α,β-epoxyalkylsilanes is discussed.
- Jankowski, Pawel,Marczak, Stanislaw,Masnyk, Marek,Wicha, Jerzy
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- Tritium-Labeled Enantiomers of Disparlure. Synthesis and in Vitro Metabolism
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Both of the enantiomers of disparlure, the gypsy moth sex attractant, have been prepared at high specific activity (58 Ci/mmol) by homogeneous tritiation of the optically active alkenyl oxiranes.An improved preparation of the racemic disparlure is also described.The radiolabeled epoxides are cleanly converted to a single product by enzymes isolated from adult gypsy moths (Lymantria dispar).Enzymatic activity obtained from male antennae showed the highest conversion; enzymes isolated from female antennae and from male and female legs showed lower activity.The identification of the metabolite as the threo-7,8-diol is established by independent synthesis and by chemical derivatizations to the diacetate, n-butylboronate, and bis(trimethylsilyl) ether.A symmetrical epoxide analogous to disparlure is converted to a diol product at a significantly lower rate.
- Prestwich, Glenn D.,Graham, Steven McG.,Kuo, Jing-Wen,Vogt, Richard G.
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p. 636 - 642
(2011/07/06)
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- Leukotriene antagonists
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Compounds having the formula: STR1 are antagonists of leukotrienes of C4, D4 and E4, the slow reacting substance of anaphylaxis. These compounds are useful as anti-asthmatic, anti-allergic, anti-inflammatory agents, and cytoprotective agents.
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- ALKYLATION OF STABILIZED ACETYLIDES IN DMSO. PREPARATION OF α,β-ACETYLENIC ALCOHOLS AND ACETALS.
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Stabilized terminal acetylenes 1 2OTHP, Ph, CH(OET)2> may be converted into lithioacetylides and readily alkylated with 1 alkyl halides in DMSO to afford functionalized disubstitued acetylenes.
- Chong, J. Michael,Wong, Susanna
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p. 5445 - 5448
(2007/10/02)
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- A New Synthesis of (Z)-7,8-Epoxy-2-methyloctadecane (Disparlure)
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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
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p. 860 - 861
(2007/10/02)
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- Preparation of unsaturated alcohols
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A process for the production of cis and trans isomers of compounds having the formula STR1 in which R, R' and R" are independently hydrogen or alkyl groups having from 1 to 20 carbon atoms, comprising (a) reacting the corresponding cis or trans isomer of a compound having the formula STR2 in which Q is an alkyl group having from 1 to 20 carbon atoms, with paraformaldehyde and (b) hydrolyzing the resulting product to produce the unsaturated alcohol.
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