- Mechanistic Insights into the Formation of δ-Lactones by Cerium-Catalyzed Aerobic Coupling of β-Oxoesters with Enol Acetates
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δ-Valerolactone derivatives are formed by the cerium-catalyzed, aerobic coupling of β-oxoesters with enol acetates and dioxygen. The products possess a 1,4-diketone moiety, thus, the conversion can be regarded as an Umpolung since the β-oxoesters are oxidized to electrophilic α-radicals. The transformation has similarities to the Baeyer-Villiger oxidation (BVO) where the higher substituted residue migrates. An endoperoxidic oxycarbenium ion comparable to the Criegee intermediate in the BVO is proposed as a reaction intermediate in this case of the oxidative C?C coupling reaction, but in contrast to the BVO, the less substituted alkyl residue migrates. It was demonstrated by the conversion of β-oxoesters with two stereocenters that this 1,2-alkyl shift proceeds with retention of configuration. A radical chain mechanism of the coupling reaction was furthermore evidenced by the conversion of enol acetates and β-oxoesters with cyclopropyl substituents. Isolation and characterization of products with opened cyclopropane rings established the constitution of radical intermediates.
- Christoffers, Jens,Speldrich, Jean-Marico
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p. 907 - 914
(2021/01/18)
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- Oxidation of Alkynyl Boronates to Carboxylic Acids, Esters, and Amides
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A general efficient protocol was developed for the synthesis of carboxylic acids, esters, and amides through oxidation of alkynyl boronates, generated directly from terminal alkynes. This protocol represents the first example of C(sp)?B bond oxidation. This approach displays a broad substrate scope, including aryl and alkyl alkynes, and exhibits excellent functional group tolerance. Water, primary and secondary alcohols, and amines are suitable nucleophiles for this transformation. Notably, amino acids and peptides can be used as nucleophiles, providing an efficient method for the synthesis and modification of peptides. The practicability of this methodology was further highlighted by the preparation of pharmaceutical molecules.
- Li, Chenchen,Li, Ruoling,Zhang, Bing,Zhao, Pei,Zhao, Wanxiang
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supporting information
p. 10913 - 10917
(2020/05/25)
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- Cyclopropylacetic acid production method
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The invention relates to a novel synthesis route of cyclopropylacetic acid. Diethyl malonate is used as a raw material, and through three steps of reactions of a substitution reaction, a hydrolysis reaction and a decarboxylic reaction, the cyclopropylacetic acid is synthesized with a high yield. The provided cyclopropylacetic acid production method is a production method which is high in yield, low in cost, easy to operate and suitable for industrialization.
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Paragraph 0019; 0022
(2019/10/01)
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- Preparation method of acid with different substituent groups
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The invention discloses a preparation method of an acid with different substituent groups. A terminal alkyne is lithiated with n-butyllithium, and then reacts with isopropoxyboronic acid pinacol ester, hydrogen chloride is added to achieve quenching, then the obtained reaction product is oxidized by an oxidizing agent, and the oxidized reaction product is separated and purified to obtain the acid.The method of the invention has the advantages of simplicity in operation, one-pot process preparation, no metal catalysis, nontoxic reagents, greenness, environmental friendliness and high atomic utilization rate, and provides a novel and quick way for preparing the acid with different substituent groups; and the obtained acid is an important fine chemical product, and can be widely used in fields of medicines, pesticides, spices and other industries.
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Paragraph 0033-0037
(2019/10/23)
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- Direct Carbon Isotope Exchange through Decarboxylative Carboxylation
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A two-step degradation-reconstruction approach to the carbon-14 radiolabeling of alkyl carboxylic acids is presented. Simple activation via redox-active ester formation was followed by nickel-mediated decarboxylative carboxylation to afford a range of complex compounds with ample isotopic incorporations for drug metabolism and pharmacokinetic studies. The practicality and operational simplicity of the protocol were demonstrated by its use in an industrial carbon-14 radiolabeling setting.
- Kingston, Cian,Wallace, Michael A.,Allentoff, Alban J.,Degruyter, Justine N.,Chen, Jason S.,Gong, Sharon X.,Bonacorsi, Samuel,Baran, Phil S.
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supporting information
p. 774 - 779
(2019/01/14)
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- OXADIAZINE COMPOUNDS AND METHODS OF USE THEREOF
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The present disclosure relates to oxadiazine compounds, pharmaceutical compositions comprising an effective amount of an oxadiazine compound and methods for using an oxadiazine compound in the treatment of a neurodegenerative disease, comprising administering to a subject in need thereof an effective amount of an oxadiazine compound.
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Paragraph 0688
(2017/03/14)
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- Gas phase thermal reactions of exo-8-cyclopropylbicyclo[4.2.0]oct-2-ene (1-exo)
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The title compound 1-exo (with minor amounts of its C8 epimer 1-endo) was prepared by Wolff-Kishner reduction of the cycloadduct of 1,3-cyclohexadiene and cyclopropylketene. The [1,3]-migration product 2-endo was synthesized by efficient selective cyclopropanation of endo-5-vinylbicyclo[2.2.2]oct-2-ene at the exocyclic π-bond. Gas phase thermal reactions of 1-exo afforded C8 epimerization to 1-endo, [1,3]- migrations to 2-exo and 2-endo, direct fragmentation to cyclohexadiene and vinylcyclopropane, and CPC rearrangement in the following relative kinetic order: kep > k13 > kf > kCPC.
- Leber, Phyllis A.,Nocket, Anthony J.,Hancock-Cerutti, William,Bemis, Christopher Y.,Khine, Wint Khant,Mohrbacher III, Joseph A.,Baldwin, John E.
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p. 1527 - 1543
(2014/03/21)
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- Experimental evidence of a cyclopropylcarbinyl conjugative electronic effect
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Bicyclo[3.2.0]hept-2-enes undergo thermal rearrangement to norbornenes via diradical transition structures. The synthesis of exo-7-cyclopropylbicyclo[3.2. 0]hept-2-ene has been achieved by cycloaddition of cyclopentadiene and cyclopropylketene, generated by treatment of cyclopropylacetyl chloride with triethylamine. A comparison of the cyclopropyl substituent effect with that of other C7 substituents provides experimental evidence of an electron-donating conjugative effect on the transient diradical transition structure in the thermal reaction of exo-7-cyclopropylbicyclo[3.2.0]hept-2-ene. The Royal Society of Chemistry.
- Leber, Phyllis A.,Nocket, Anthony J.,Wipperman, Matthew F.,Zohrabian, Sylvia,Bemis, Christopher Y.,Sidhu, Munsha K.
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supporting information
p. 5994 - 5997
(2013/09/12)
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- Quinolizinone type compounds
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Antibacterial compounds having the formula STR1 and the pharmaceutically acceptable salts, esters and amides thereof, preferred examples of which include those compounds wherein A is =CR6 --; R1 is cycloalkyl of from three to eight carbon atoms or substituted phenyl; R2 is selected from the group consisting of STR2 R3 is halogen; R4 is hydrogen, loweralkyl, a pharmaceutically acceptable cation, or a prodrug ester group; R5 is hydrogen, loweralkyl, halo(loweralkyl), or --NR13 R14 ; and R6 is halogen, loweralkyl, halo(loweralkyl), hydroxy-substituted loweralkyl, loweralkoxy(loweralkyl), loweralkoxy, or amino(loweralkyl), as well as pharmaceutical compositions containing such compounds and the use of the same in the treatment of bacterial infections.
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- Free Radical Rearrangements in Uracil Derivatives
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As part of an effort to develop general probes for radical reactions involving DNA bases, several uracil derivatives were synthesized.The rates of the cyclopropyl carbinyl rearrangement in these systems were evaluated by means of competition experiments.The results indicate that when a cyclopropyl group is substituted in the 5-position of uracil, the rearrangement occurs very slowly - with a rate constant of -1.On the other hand, the analog of the 5-hexenyl radical cyclization onto the 5,6-double bond of uracil derivatives occurs with rates which were similar to the parent process: (4.0-8.9)E4 s-1.The experimental results along with semiempirical calculations show that radicals 23 and 25 are unusually stable species.These results explain why no rearrangements are observed when a cyclopropyl-substituted thymine dimer is cleaved by reductive single electron transfer.
- Fenick, David J.,Falvey, Daniel E.
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p. 4791 - 4799
(2007/10/02)
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- The synthesis of methyl cyclopropylacetate by palladium(II) acetate catalysed reaction of diazomethane with vinyl group
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The methyl cyclopropylacetate was prepared in high yield by Palladium(II) acetate catalysed reaction of vinyl acetic acid with an excess of diazomethane. The cyclopropylacetonitrile was prepared from allyl cyanide by the same method.
- Basnak,Jurkovic,Basnakova
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p. 773 - 782
(2007/10/02)
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- Reaction of Dilithiated Carboxylic Acids with Iodine: Evidence for the Formation of a Radical Anion Intermediate
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The mechanism for oxidative dimerization of carboxylic acid dianions involves single electron transfer to iodine, producing an organic anion radical.Rearrangement of this species was observed with suitable substrates at a rate competitive with intermolecular reactions.The radical anion can dimerize or react with iodine.The iodide thus generated can be isolated (reaction with excess of iodine) or can participate in a polar SN2-type reaction sequence leading to dimeric products (reaction with 1/2 equiv of iodine).The interference by free amines (liberated during the metalation with lithium amides) is rationalized by the formation of a charge-transfer complex with iodine which decomposes, liberating protons.
- Renaud, Philippe,Fox, Marye Anne
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p. 3745 - 3752
(2007/10/02)
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- TRANSFORMATION OF β-ALKENYL-β-PROPIOLACTONES INTO CYCLOPROPYLACETIC ACIDS UTILIZING HYDROBORATION
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The reaction of β-alkenyl-β-propiolactones with 9-borabicyclononane and subsequent treatment with sodium methoxide gave cyclopropylacetic acids in good yields.
- Kawashima, Masatoshi,Fujisawa, Tamotsu
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p. 1273 - 1274
(2007/10/02)
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- Low Temperature Grignard Reactions with Pure Mg Slurries. Trapping of Cyclopropylmethyl and Benzocyclobutenylmethyl Grignard Reagents with CO2
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Cyclopropylmethyl bromide reacts readily at -75 deg with a Mg/THF slurry formed by evaporation of Mg in a rotating-solution reactor to yield after carbonation cyclopropyl acetic acid and 4-pentenoic acid in a ratio of 11:1.Addition of benzaldehyde to the Grignard solution again predominantly yields the addition product containing the cyclopropylmethyl unit.Using the same low temperature Grignard method, benzocyclobutenyl acetic acid is isolated upon carbonation of the Grignard reagent derived from the corresponding bromide, whereas under normal conditions o-vinylphenylacetic acid, the product corresponding to ring cleaved Grignard is obtained.
- Kuendig, Ernst Peter,Perret, Celia
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p. 2606 - 2613
(2007/10/02)
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- Pyridine esters of cyclopropane-carboxylic acid
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Heterocyclic organic esters and thioesters characterized by the presence of one or two cyclopropane moieties, synthesis thereof, and compositions thereof for the control of mites and ticks.
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- Control of Acarina by esters of cyclopropane acids
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Methods and compositions for the control of Acarina employing esters of cyclopropane carboxylic acids described herein.
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