- Synthesis of malhamensilipin A exploiting iterative epoxidation/chlorination: experimental and computational analysis of epoxide-derived chloronium ions
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We report a 12-step catalytic enantioselective formal synthesis of malhamensilipin A (3) and diastereoisomeric analogues from (E)-2-undecenal. The convergent synthesis relied upon iterative epoxidation and phosphorus(v)-mediated deoxydichlorination reactions as well a titanium-mediated epoxide-opening to construct the C11-C16 stereohexad. The latter transformation occurred with very high levels of stereoretention regardless of the C13 configuration of the parent epoxide, implicating anchimeric assistance of either the γ- or δ-chlorine atoms, and the formation of chloretanium or chlorolanium ions, respectively. A computational analysis of the chloronium ion intermediates provided support for the involvement of chlorolanium ions, whereas the potential chloretanium ions were found to be less likely intermediates on the basis of their greater carbocationic character.
- Saska,Lewis,Paton,Denton
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- IONIZABLE AMINE LIPIDS
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The disclosure provides ionizable amine lipids and salts thereof (e.g., pharmaceutically acceptable salts thereof) useful for the delivery of biologically active agents, for example delivering biologically active agents to cells to prepare engineered cells. The ionizable amine lipids disclosed herein are useful as ionizable lipids in the formulation of lipid nanoparticle-based compositions.
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Page/Page column 69-70; 72
(2020/05/15)
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- Facile and efficient syntheses of (11Z,13Z)-hexadecadienal and its derivatives: Key sex pheromone and attractant components of notodontidae
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Syntheses of (11Z,13Z)-hexadecadienal (1), (11Z,13Z)-hexadecadienol (2), (11Z,13Z)-hexadecadien-1-yl acetate (3), and (Z)-13-hexadecen-11-ynal (4) from commercially available starting material 10-bromo-1-decanol are reported. These (Z,Z)-dienes and conjugated en-yne moieties are common in sex pheromone and attractant components for many Notodontide insect pests. The synthetic scheme, using the C10 + C3 + C3 strategy, was mainly based on three key steps: Alkylation of lithium alkyne under a low temperature, cis-Wittig olefination of the aldehyde with propylidentriphenylphosphorane, and hydroboration-protonolysis of alkyne. This synthetic route provided (11Z,13Z)-hexadecadienal (1) in a 23.0% total yield via an eight-step sequence, alcohol (2) in a 21.9% total yield, acetate (3) in a 21.4% total yield, and (Z)-13-hexadecen-11-ynal (4) in a 34.7% total yield. This simple strategy provides a new way to achieve syntheses of the key sex pheromones of Notodontide insect pests.
- Liu, Fu,Kong, Xiangbo,Zhang, Sufang,Zhang, Zhen
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- Protecting-Group-Free Total Synthesis of Chatenaytrienin-2
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An efficient seven-step, protecting-group-free first total synthesis of chatenaytrienin-2 based on ring-closing metathesis and C(sp)-C(sp3) Sonogashira coupling with a 36.5% overall yield has been described. The ready availability of starting m
- Kunkalkar, Rupesh A.,Fernandes, Rodney A.
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p. 12216 - 12220
(2019/10/11)
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- Ni-Catalyzed Site-Selective Dicarboxylation of 1,3-Dienes with CO2
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A site-selective catalytic incorporation of multiple CO2 molecules into 1,3-dienes en route to adipic acids is described. This protocol is characterized by its mild conditions, excellent chemo- and regioselectivity and ease of execution under CO2 (1 atm), including the use of bulk butadiene and/or isoprene feedstocks.
- Tortajada, Andreu,Ninokata, Ryo,Martin, Ruben
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supporting information
p. 2050 - 2053
(2018/02/19)
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- Hydroxyl-Assisted trans-Reduction of 1,3-Enynes: Application to the Formal Synthesis of (+)-Aspicilin
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1,3-Enynes are hardly amenable to trans-hydrometalation reactions, because they tend to bind the standard ruthenium catalysts too tightly. However, catalysts comprising a [Cp?Ru-Cl] unit allow such compounds to be used, provided they contain an OH group next to the triple bond. This aspect is illustrated by a formal synthesis of the lichen-derived macrolide aspicilin. The required macrocyclic enyne precursor was formed by an efficient ring-closing alkyne metathesis reaction.
- Schaubach, Sebastian,Michigami, Kenichi,Fürstner, Alois
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p. 202 - 208
(2016/12/24)
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- Catalytic Enantioselective Dihalogenation and the Selective Synthesis of (-)-Deschloromytilipin A and (-)-Danicalipin A
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A titanium-based catalytic enantioselective dichlorination of simple allylic alcohols is described. This dichlorination reaction provides stereoselective access to all common dichloroalcohol building blocks used in syntheses of chlorosulfolipid natural products. An enantioselective synthesis of ent-(-)-deschloromytilipin A and a concise, eight-step synthesis of ent-(-)-danicalipin A are executed and employ the dichlorination reaction as the first step. Extension of this system to enantioselective dibromination and its use in the synthesis of pentabromide stereoarrays relevant to bromosulfolipids is reported. The described dichlorination and dibromination reactions are capable of exerting diastereocontrol in complex settings allowing X-ray crystal structure analysis of natural and unnatural diastereomers of polyhalogenated stereohexads.
- Landry, Matthew L.,Hu, Dennis X.,McKenna, Grace M.,Burns, Noah Z.
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supporting information
p. 5150 - 5158
(2016/05/19)
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- Facile synthesis of N-substituted amides from alkenes and amides by a Bronsted acid mediated electrophilic addition reaction
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A facile and widely applicable method for the synthesis of N-substituted amides from alkenes and amides using Bronsted acids was developed. Treatment of various alkenes with amides and an alkali metal halide or methanesulfonic acid in trifluoroacetic acid afforded the corresponding N-substituted amides in good to high yield. The reaction proceeds via the direct electrophilic addition of the amides to the alkenes. Various functional groups such as ester, ether, imide, amide, and halogen were tolerated under the reaction conditions. High substrate-dependent cis stereoselectivity in the synthesis was also observed for methylenecyclohexane and methylcyclohexene derivatives possessing a substituent at the 4-position. Furthermore, a practical application of this reaction has been demonstrated by the synthesis of an intermediate of a bioactive compound on a large scale. Georg Thieme Verlag Stuttgart New York.
- Mihara, Karin,Okada, Iku,Chiba, Kazuhiro,Kitano, Yoshikazu
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p. 1455 - 1462
(2014/06/10)
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- Selective reduction of carboxylic acids to aldehydes catalyzed by B(C 6F5)3
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B(C6F5)3 efficiently catalyzes hydrosilylation of aliphatic and aromatic carboxylic acids to produce disilyl acetals under mild conditions. Catalyst loadings can be as low as 0.05 mol %, and bulky tertiary silanes are favored to give selectively the acetals. Acidic workup of the disilyl acetals results in the formation of aldehydes in good to excellent yields.
- Bezier, David,Park, Sehoon,Brookhart, Maurice
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p. 496 - 499
(2013/03/29)
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- New prodrugs of Adefovir and Cidofovir
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New Adefovir (PMEA) prodrugs with a pro-moiety consisting of decyl or decyloxyethyl chain bearing hydroxyl function(s), hexaethyleneglycol or a (5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl unit were prepared starting from the tetrabutylammonium salt of the phosphonate drug and an appropriate alkyl bromide or tosylate. Analogously, two esters of Cidofovir [(S)-HPMPC] bearing a hexaethyleneglycol moiety were prepared. The activity of the prodrugs was evaluated in vitro against different virus families. A loss in the antiviral activities of the hydroxylated decyl or decyloxyethyl esters and hexaethyleneglycol esters of PMEA against human immunodeficiency virus (HIV) and herpesviruses [including herpes simplex virus (HSV), varicella-zoster virus (VZV), and human cytomegalovirus (CMV)] occurred in comparison with the parent compound. On the other hand, the (5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl ester of PMEA showed significant activities against HIV and herpesviruses. (S)-HPMPC prodrugs exhibited anti-cytomegalovirus activities in the same range as the parent drug, whereas the anti-HSV and anti-VZV activities were one- to seven-fold lower than that of Cidofovir.
- Tichy, Tomá?,Andrei, Graciela,Dra?ínsky, Martin,Holy, Antonín,Balzarini, Jan,Snoeck, Robert,Kre?merová, Marcela
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p. 3527 - 3539
(2011/07/09)
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- Functional Polymers for Layer-by-Layer Construction of Multilayers via Chemoselective Immobilization
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This paper reports detailed synthesis and characterization of polymers with functional groups for chemoselective immobilization. Various types of 1,4-diiodo-2,5-dialkoxybenzene monomers containing hydrophobic and hydrophilic groups with chemoselective fun
- Lee, Dong-Chan,Chang, Bong-Jun,Morales, Gustavo M.,Jang, Young Ah,Ng, Man-Kit,Heller, Stephen T.,Yu, Luping
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p. 1849 - 1856
(2007/10/03)
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- A novel layer-by-layer approach to immobilization of polymers and nanoclusters
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This paper reports a simple method for the multilayer immobilization of conjugated polymers, gold nanoparticles on solid supports. Poly(phenyenevinylene) functionalized with aldehyde and aminooxy groups was chemoselectively immobilized onto both glass and
- Chan, Eugene W. L.,Lee, Dong-Chan,Ng, Man-Kit,Wu, Guohui,Lee, Ka Yee C.,Yu, Luping
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p. 12238 - 12243
(2007/10/03)
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- Novel enantioselective synthesis of penaresidin A and Allo-penaresidin A via the construction of a highly functionalized azetidine
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A new and highly enantioselective synthesis of penaresidin A has been achieved via the construction of a highly functionalized azetidine with the requisite stereogenic centers, which can also be regarded as an advanced intermediate for the synthesis of penaresidin B and penazetidine A.
- Liu, Ding-Guo,Lin, Guo-Qiang
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p. 337 - 340
(2007/10/03)
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- Structure based interference with insect behaviour - Cyclopropene analogues of pheromones containing Z-alkenes
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Analogues of the pheromones of three insect species (Musca domestica L., Plutella xylostella L. and Ephestia elutella Hbn.) in which a Z-alkene has been replaced by a 1,2-disubstituted cyclopropene have been synthesized. The analogues interfere with normal mating behaviour for each species.
- Al Dulayymi, Juma'a R.,Baird, Mark S.,Simpson, Michael J.,Nyman, Susan,Port, Gordon R.
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p. 12509 - 12520
(2007/10/03)
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- The synthesis of natural R-(-)enantiomers from three galbanum resin macrolides
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The three macrolides 1, 2 and 3 isolated from galbanum resin were synthesized starting from ω-bromoacetals 9. The key step is the buffered intramolecular Wittig reaction of the ylides 14 and 23 to afford the α,β-unsaturated lactones 15, 16 and 24. Hydrogenation of these lactones gives the title macrolides in (R)-configuration.
- Bestmann,Kellermann
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p. 1257 - 1261
(2007/10/02)
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- The synthesis of β-keto lactones via cyclization of β-keto ester dianions or the cyclization of Meldrum's acid derivatives
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Two new methods to synthesize macrocyclic β-keto lactones have been developed.The first involves the synthesis of ω-halo-β-keto esters and an intramolecular alkylation of the dianions to these compounds.The reaction is complicated by elimination in the small and medium ring systems and by difficulties in purifying the final products.However, it is possible to obtain modest yields of the desired β-keto lactones.This procedure was used to synthesize the 25- and 27-membered ring β-hydroxy lactones that are the constituents of termite defense compounds.The second method involves the thermolysis of acylated Meldrum's acid derivatives, which leads directly to β-keto lactones.This process gives modest yields of macrocyclic systems and good yield of the unsubstituted 3-oxopentan-5-olide (25) .The 14-membered macrocyclic β-keto lactone 9j has a complex 1H NMR spectrum, which has been interpreted in terms of multiple conformations.The temperature dependence of the NMR spectrum of 9j is consistent with entropic, rather than enthalpic, control of the equilibrium.Quasiharmonic entropy calculations are consistent with this model.
- Lermer, Leonard,Neeland, Edward G.,Ounsworth, James P.,Sims, Russell J.,Tischler, Samuel A.,Weiler, Larry
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p. 1427 - 1445
(2007/10/02)
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- SYNTHESIS OF THE ACETATE OF OCTADECA-trans-2,cis-13-DIEN-1-OL, A COMPONENT OF THE SEX PHEROMONES OF synanthedon tipuliformis AND Zeuzera pyrina
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A new synthesis of the acetate of octadeca-trans-2,cis-13-dien-1-ol based on the alkylation of propargyl alcohol with pentadec-cis-10-enyl bromide, obtained from the readily accessible decamethylene bromohydrin, has been effected.
- Sorochinskaya, A. M.,Kovalev, B. G.
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p. 228 - 230
(2007/10/02)
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- Stereospecific Diene Synthesis using Acetylene Carbocupration; Preparation of Navel Orangeworm Pheromone and Leukotriene Analogues
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Experimental conditions are described for the conversion of lithium dialkylcuprates into the corresponding doubly vinylogous 1Z,3Z-dienylcuprates using acetylene carbocupration.These dienylcuprates have been trapped with a range of electrophiles to form cconjugated Z,Z-dienes in a highly stereospecific manner.The application of this methodology to the synthesis of hexadeca-11Z,13Z-dienal, a principle component of navel orangeworm pheromone, and simple leukotriene B4 analogues is also reported.
- Furber, Mark,Taylor, Richard J. K.,Burford, S. Cliff
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p. 1809 - 1816
(2007/10/02)
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- A FACILE SYNTHESIS OF 11-DODECYNAL
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A three-step synthesis of 11-dodecynal is described.
- Chen, Shin-Yih,Joullie, Madeleine M.
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p. 591 - 598
(2007/10/02)
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