- Synthesis of a biofuel target through conventional organic chemistry
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In this work, the biofuel target compound 2-ethyl-5,5-dimethylcyclopenta-1,3-diene (1) and its exo isomers (9a and 9b), were successfully synthesized via two different pathways from the common intermediate 4,4-dimethylcyclopent-2-ene-1-one (2). The first pathway produced the endocyclic product as a pure isomer via a triflate intermediate obtained from ketone 2 in 60% yield, followed by copper-catalyzed coupling with ethyl magnesium bromide in 63% yield. The second pathway employed a Grignard reaction with ketone 2, which generated an alcohol that was immediately subjected to mild acid-catalyzed elimination to yield primarily a mixture of exo isomers 9a and 9b in 46% yield. The preparation method developed by this work allowed for the production of a sufficient quantity of these targets to evaluate their fuel properties, which will be reported in a separate study.
- Page, Jordan P.,Robinson, Joshua W.,Albrecht, Karl O.,Cosimbescu, Lelia
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- Synthesis and Neurotrophic Activity Studies of Illicium Sesquiterpene Natural Product Analogues
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Neurotrophic natural products hold potential as privileged structures for the development of therapeutic agents against neurodegeneration. However, only a few studies have been conducted to investigate a common pharmacophoric motif and structure–activity relationships (SARs). Here, an investigation of structurally more simple analogues of neurotrophic sesquiterpenes of the illicium family is presented. A concise synthetic route enables preparation of the carbon framework of (±)-Merrilactone A and (±)-Anislactone A/B on a gram scale. This has allowed access to a series of structural analogues by modification of the core structure, including variation of oxidation levels and alteration of functional groups. In total, 15 derivatives of the natural products have been synthesized and tested for their neurite outgrowth activities. Our studies indicate that the promising biological activity can be retained by structurally simpler natural product analogues, which are accessible by a straightforward synthetic route.
- Richers, Johannes,P?thig, Alexander,Herdtweck, Eberhardt,Sippel, Claudia,Hausch, Felix,Tiefenbacher, Konrad
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p. 3178 - 3183
(2017/03/13)
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- Ring Opening of Bicyclo[3.1.0]hexan-2-ones: A Versatile Synthetic Platform for the Construction of Substituted Benzoates
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Described is the development of a highly efficient 2πdisrotatory ring-opening aromatization sequence using bicyclo[3.1.0]hexan-2-ones. This unprecedented transformation efficiently proceeds under thermal conditions and allows facile construction of uniquely substituted and polyfunctionalized benzoates. In the presence of either amines or alcohols formation of substituted anilines or ethers, respectively, is achieved. Additionally, the utility of this method was demonstrated in a short synthesis of sekikaic acid methyl ester. Cracked open: A highly efficient thermal 2πdisrotatory ring-opening aromatization sequence of bicyclo[3.1.0]hexan-2-ones is described. The transformation proceeds in sulfolane to give uniquely substituted benzoates. In the presence of either amines or alcohols, formation of substituted anilines or ethers, respectively, is achieved.
- Feierfeil, Johannes,Grossmann, Adriana,Magauer, Thomas
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supporting information
p. 11835 - 11838
(2015/10/05)
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- Concise total syntheses of the bioactive mesotricyclic diterpenoids jatrophatrione and citlalitrione
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The highly functionalized [5.9.5] tricyclic framework resident in jatrophatrione (1) and citlalitrione (2) has been synthesized. The route begins with the tandem anionic oxy-Cope rearrangement/methylation/transannular ene cyclization of 21 and subsequent introduction of a conjugated enone double bond. Hydroxyl-directed 1,4-reduction of this functionality in 25 with LiAlH4/Cul/hexamethylphosphoramide/tetrahydrofuran sets the stage for the implementation of a Grob fragmentation and expedited generation of 27. Stereocontrolled intramolecular hydrosilylation allows for the subsequent introduction of a cyclic carbonate as in 53. This intermediate undergoes remarkably efficient, fully regiocontrolled Treibs reaction to generate 54, with this maneuver serving as a pivotal step for making 1 available five steps later. Treatment of 1 with m-chloroperbenzoic acid leads to 2, with attack occurring preferentially on a α-face of the double bond more remote to the carbonyl.
- Yang, Jiong,Long, Yun Oliver,Paquette, Leo A.
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p. 1567 - 1574
(2007/10/03)
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- A simple strategy for spirocyclopentannulation of cyclic ketones. Formal total synthesis of (±)-acorone
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A general and simple methodology for spirocyclopentannulation of cyclic ketones (or 4,4-disubstituted cyclopentenones from acyclic ketones) and its application in the synthesis of the spirodienone 7 via a prochiral precursor constituting a formal total synthesis of (±)-acorone (6), are described.
- Srikrishna, Adusumilli,Kumar, P. Praveen,Viswajanani, Ranganathan
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p. 1683 - 1686
(2007/10/03)
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- A Comparison of the Reactions of lithium with α,β-Unsaturated Ketones and Those of Other Acyl Anion Equivalents Containing Sulfur
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The factors influencing the site of attack of lithium (1) with enones were investigated.Cyclohexenone (2) was chosen as a model compound, and conjugate addition occurred in THF-HMPA or DME; this mode of addition was also promoted by a potassium counterion.When the reaction was carried out with other enones, conjugate addition in THF-HMPA or DME was only observed if the β-position or the α,β-unsaturated ketone was not disubstituted. 1,4-Addition of 1 could be accomplished by preparation of the cuprate.The use of this approach was illustrated by a preparation of 4,4-dimethylcyclopent-2-en-1-one (28).For determination of the influence of DME on the regiochemical control of the addition of other sulfur-containing anions to enones, the study was extended to the anions derived from 1,3-dithian (29), bis(phenylthio)methane (30), bis(phenylthio)(trimethylsilyl)methane (35), and bis(trimethylsilyl)(phenylthio)methane (36).With these anions, DME did not promote conjugate addition to any significant extent.
- Ager, David J.,East, Michael B.
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p. 3983 - 3992
(2007/10/02)
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- Geminate-Substituted Cyclopentadienes. 1. Synthesis of 5,5-Dialkylcyclopentadienes via 4,4-Dialkylcyclopent-2-en-1-ones.
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A synthetic route for the preparation of 5,5,-dialkylcyclopentadienes (1) via 4,4-dialkylcyclopent-2-en-1-ones (3) is described.Beginnig with ketones (in which the two carbonyl substituents will become the two alkyl groups in the title compounds), the route traverses the Guareschi imides 5, 3,3-dialkylglutaric acids 4 and their ethyl esters 7, masked acyloins 8, cyclopentenones 3, alkohols 9, and bromides 10 to reach the dienes 1.Physical properties of five such derivates 1 and 3 (dimethyl, methylethyl,diethyl, methyl-n-propyl, and methylisopropyl) are presented.
- Holder, Richard W.,Daub, John P.,Baker, Wesley E.,Gilbert, Raymond H,Graf, Norman A.
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p. 1445 - 1451
(2007/10/02)
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- COPPER (I) CATALYSIS OF OLEFIN PHOTOREACTIONS -9. PHOTOBICYCLIZATION OF alpha -, beta -, AND gamma -ALKENYLALLYL ALCOHOLS.
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Cyclobutylcarbinyl alcohols of the bicyclo left bracket 3. 2. 0 right bracket heptane ring system are produced by UV irradiation of alpha -, beta -, and gamma -alkenylallyl alcohols in the presence of copper (I) trifluoromethanesulfonate (CuOTf). endo-2-Hydroxy epimers of bicyclo left bracket 3. 2. 0 right bracket heptan-2-ols are generated stereoselectively. This result as well as the effect of CuOTf on the **1H NMR spectrum of 4,4-dimethyl-1,6-heptadien-3-ol suggests that coordination of two C equals C bonds and the hydroxyl group with a single copper (I) is important. The derived bicyclo left bracket 3. 2. 0 right bracket heptan 2-ones fragment cleanly at 580 degree C to afford cyclopent-2-en-1-ones. Geometric isomerization competes with photobicyclization of (E)- and (Z)-octa-2,7-dien-1-ols.
- Salomon,Coughlin,Ghosh,Zagorski
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p. 998 - 1007
(2007/10/14)
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