- Practical and Selective sp3 C?H Bond Chlorination via Aminium Radicals
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The introduction of chlorine atoms into organic molecules is fundamental to the manufacture of industrial chemicals, the elaboration of advanced synthetic intermediates and also the fine-tuning of physicochemical and biological properties of drugs, agrochemicals and polymers. We report here a general and practical photochemical strategy enabling the site-selective chlorination of sp3 C?H bonds. This process exploits the ability of protonated N-chloroamines to serve as aminium radical precursors and also radical chlorinating agents. Upon photochemical initiation, an efficient radical-chain propagation is established allowing the functionalization of a broad range of substrates due to the large number of compatible functionalities. The ability to synergistically maximize both polar and steric effects in the H-atom transfer transition state through appropriate selection of the aminium radical has provided the highest known selectivity in radical sp3 C?H chlorination.
- McMillan, Alastair J.,Sieńkowska, Martyna,Di Lorenzo, Piero,Gransbury, Gemma K.,Chilton, Nicholas F.,Salamone, Michela,Ruffoni, Alessandro,Bietti, Massimo,Leonori, Daniele
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supporting information
p. 7132 - 7139
(2021/03/03)
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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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p. 10913 - 10917
(2020/05/25)
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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 0129-0133
(2019/10/23)
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- A mild method for synthesizing carboxylic acids by oxidation of aldoximes using hypervalent iodine reagents
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A mild oxidation method for the conversion of aldoximes to carboxylic acids was developed mediated by hypervalent iodine reagents. This method covers a wide range of functionalized aldoximes and proceeds under mild conditions, utilizing PhI(OH)OTs as an oxidant.
- Nakamura, Akira,Kanou, Hodaka,Tanaka, Junki,Imamiya, Akira,Maegawa, Tomohiro,Miki, Yasuyoshi
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supporting information
p. 541 - 544
(2018/02/07)
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- Unexpected dehomologation of primary alcohols to one-carbon shorter carboxylic acids using o-iodoxybenzoic acid (IBX)
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A novel and efficient transformation of primary alcohols to one-carbon shorter carboxylic acids using IBX is reported. Mechanistic studies revealed that the combination of IBX and molecular iodine produces a different active hypervalent iodine species.
- Xu, Shu,Itto, Kaori,Satoh, Masahide,Arimoto, Hirokazu
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supporting information
p. 2758 - 2761
(2014/03/21)
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- Single-molecule imaging of platinum ligand exchange reaction reveals reactivity distribution
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Single-molecule fluorescence microscopy provided information about the real-time distribution of chemical reactivity on silicon oxide supports at the solution-surface interface, at a level of detail which would be unavailable from a traditional ensemble technique or from a technique that imaged the static physical properties of the surface. Chemical reactions on the surface were found to be uncorrelated; that is, the chemical reaction of one metal complex did not influence the location of a future chemical reaction of another metal complex.
- Esfandiari, N. Melody,Wang, Yong,Bass, Jonathan Y.,Cornell, Trevor P.,Otte, Douglas A. L.,Cheng, Ming H.,Hemminger, John C.,McIntire, Theresa M.,Mandelshtam, Vladimir A.,Blum, Suzanne A.
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supporting information; experimental part
p. 15167 - 15169
(2010/12/20)
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- Novel diastereoselective synthesis of (E)-gem-dimetalloalkenes containing boron and germanium: An easy access to alkyl trimethylgermyl ketones and carboxylic acids
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A convenient, novel synthesis of (E)-gem-dimetalloalkenes containing boron and germanium from the (Z)-1-bromo-1-alkenylboronate esters has been developed. α-Bromo-(Z)-1-alkenylboronate esters readily prepared from the literature procedures smoothly underwent a reaction with freshly generated trimethylgermyllithium in hexamethylphosphoramide (HMPA) from the hexamethyldigermanium at -78°C to provide the corresponding 'ate' complexes. These 'ate' complexes underwent intramolecular nucleophilic substitution reaction to provide the corresponding (E)-1-alkenylboronate esters containing trimethylgermyl moiety. These intermediates were isolated in good yields (72-81%) and were characterized by the spectral data (1H NMR and 13C NMR). Upon oxidation of these intermediates with trimethylamine-N-oxide, the corresponding alkyl trimethylgermyl ketones were prepared in good yields (78-86%)). Oxidation with alkaline hydrogen peroxide followed by acidification afforded the corresponding carboxylic acids in good yields (82-88%). Georg Thieme Verlag Stuttgart.
- Bhat, Narayan G.,Varghese, Nisha
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p. 2023 - 2024
(2008/02/09)
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- A novel synthesis of (Z)-2-(1-trimethylgermyl-1-alkenyl)-1,3,2- dioxaborinanes and their conversion into carboxylic acids
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A novel procedure for preparing heterocyclic compounds such as (Z)-2-(1-trimethylgermyl-1-alkenyl)-1,3,2-dioxaborinanes based on 1-trimethylgermyl-1-alkynes is described. 1-Trimethylgermyl-1-alkynes easily obtainable by deprotonation of 1-alkynes with n-butyllithium followed by treatment with trimethylgermanium chloride, are readily hydroborated in n-pentane in the presence of boron trichloride in hexane at 0°C for 3 h. The resulting supernatant clear solution was separated from boron trichloride-methyl sulfide complex. It was then reacted with 1,3-propane diol at 0°C for 0.5 h. The resulting representative (Z)-2-(1-trimethylgermyl-1- alkenyl)-1,3,2-dioxaborinanes were isolated in good yields (65-86%) and in high stereochemical purities (>98%) as evidenced by NMR spectral data. The carbon skeletons present in these intermediates were confirmed by alkaline hydrogen peroxide oxidation to the corresponding carboxylic acids.
- Bhat, Narayan G.,Caga-Anan, Zerremi,Leija, Reynaldo
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p. 5109 - 5111
(2007/10/03)
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- Solid-state chlorodecarboxylation of mono- and dicarboxylic acids with the Pb(OAc)4-MCl system
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Solid state reactions of acids RCOOH (R = n-C7H15, BuC(Et)H, n-C9H19, PhCH2, PhCH 2CH2, H2C=CH(CH2)8, or MeOOC(CH2)3) with Pb(OAc)4 combined with KCl, NaCl, CdCl2, or NH4Cl in the absence of a solvent and without mechanical activation afford chlorohydrocarbons RCl. The corresponding reactions of acids HOOC(CH2)nCOOH (n = 3-6) give dichloroalkanes Cl(CH2)nCl and γ-butyrolactone (n = 3).
- Nikishin,Sokova,Chizhov,Makhaev,Kapustina
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p. 2200 - 2204
(2007/10/03)
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- Solid-phase reactions of alkanedicarboxylic acids with the Pb(OAc) 4-NH4Cl system
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The title reactions of HOOC(CH2)nCOOH acids afford α,ω-dichloroalkanes (n = 3, 4, 6) and lactones (n = 3, 4) as the main products.
- Nikishin, Gennady I.,Sokova, Lyubov L.,Makhaev, Viktor D.,Kapustina, Nadezhda I.
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p. 264 - 265
(2007/10/03)
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- An improved and practical sharpless oxidation of primary alcohols to the carboxylic acids
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An improved and practical procedure for the oxidation of primary alcohols to the carboxylic acids under Sharpless's conditions (NaIO4/RuCl3.H2O/water/acetonitrile) using ethyl acetate as the solvent, in place of toxic and ecologically undesirable carbon tetrachloride, is described.
- Prashad, Mahavir,Lu, Yansong,Kim, Hong-Yong,Hu, Bin,Repic, Oljan,Blacklock, Thomas J.
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p. 2937 - 2942
(2007/10/03)
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- Novel Fused Bicyclic Sulphur Compounds
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Novel fused (cis-octahydrothienothiepine, cis-hexahydrothieno-1,4-oxathiine and cis-hexahydrothieno-1,4-dithiine) and spiro (1,4,6-trithiaspirononane and 1,4,7-trithiaspirononane) bicyclic compounds containing sulphur have been synthesized and their structures confirmed by NMR spectroscopy.For their synthesis, reactions of nucleophiles, including Grignard reagents, with trans-2,3-dichlorotetrahydrothiophene were investigated.Improved methods of forming sulphides from Na2S and haloalkanes have been developed. 1-Bromo-4-chlorobutane was shown to form the specific Grignard reagent, Cl4MgBr.
- Delaney, Paul A.,Johnstone, Robert A. W.,Leonard, Paul A.,Regan, Peter
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p. 285 - 289
(2007/10/02)
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- OXYGEN TRANSFER FROM PERCARBOXYLIC ACIDS AND ALKYL HYDROPEROXIDES TO (MESO-TETRAPHENYLPORPHINATO)IRON(III) AND -CHROMIUM(III)
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The second order rate constants (kYOOH) for the reaction of (meso-tetraphenylporphinato)iron(III) chloride ((T-PP)FeIII(Cl)) with a series of percarboxylic acids and alkyl hydroperoxides (species YOOH) were determined in methanol by the trapping of the hypervalent iron-oxo porphyrin species with 2,4,6-tri-tert-butylphenol.The oxygen donors, TOOH, were chosen so that the leaving species, YOH, possessed pKa values spaced between 3.8 and 16.7.Values of kYOOH for oxidation of (TPP)CrIII(Cl) to (TPP)CrV(O) have been determined in dichloromethane by following the formation of ((TPP)CrIV)2O.The latter arises by non-rate-determining trapping of (TPP)CrV(O) by unreacted (TPP)CrIII(Cl).A plot of log kYOOH for (TPP)FeIII(Cl) versus the log of kYOOH for (TPP)CrIII(Cl) exhibits two linear portions.A slope of about unity is seen when YOOH represents percarboxylic acids.This reflects the similarity in mechanism for the reactions of percarboxylic acids with (TPP)FeIII(Cl) and (TPP)CrIII(Cl).Since phenylacetic acid is obtained as the product in the reaction of both (TPP)FeIII(Cl) and (TPP)CrIII(Cl) with phenylperacetic acid, the common mechanism is one of heterolytic scission of the percarboxylic acid O-O bond.With (TPP)CrIII(Cl), a linear free-energy plot of log kYOOH versus the pKa of the leaving YOH is shared by both percarboxylic acids and hydroperoxides.This finding is to be expected if oxygen transfer from hydroperoxides to (TPP)CrIII(Cl) shares with the percarboxylic acids the common mechanism of O-O bond heterolysis.A change in mechanism of oxygen transfer in the reactions of (TPP)FeIII(Cl) with percarboxylic acids and alkyl hydroperoxides is shown by the breaks in plots of the log kYOOH versus either the pKa of YOH or log kYOOH for (TPP)CrIII(Cl).The rate-limiting step on reaction of the less acidic alkyl hydroperoxides with (TPP)FeIII(Cl) is suggested to involve homolytic O-O bond scission to provide an intimate IV(OH)(X)-.O-alkyl> pair which may then dissociate as such or after H. transfer dissociate to (+.TPP)FeIV(O)(X) + HO-alkyl.Differentiation of mechanism on the basis of the products of YOH oxidation cannot be made.Details are discussed in the paper.The various linear free-energy plots exhibit a surprising independence of steric effects in the hydroperoxides.
- Lee, William A.,Yuan, Lung-Chi,Bruice, Thomas C.
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p. 4277 - 4283
(2007/10/02)
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- Influence of Nitrogen Base Ligation and Hydrogen Bonding on the Rate Constants for Oxygen Transfer from Percarboxylic Acids and Alkyl Hydroperoxides to (meso-Tetraphenylporphinato>manganese(III) Chloride
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Equilibrium constants for axial ligation of imidazole (ImH), N-methylimidazole (N-MeIm), 4'-(imidazo-1-yl)-acetophenone (NAcPhIm), 2,6-lutidine (2,6-Py), and 3,4-lutidine (3,4-Py) with (meso-tetraphenylporphinato)manganese chloride ((TPP)MnIIICl) have been determined.The rates of oxygen atom transfer from percarboxylic acids and alkyl hydroperoxides (YOOH) to the manganese(III) porphyrin in the presence of varying concentrations of the nitrogen bases were determined.For this purpose, 2,2-diphenyl-1-picrylhydrazine (DPPH) was employed as a trap for the generated higher valent oxo-manganese porphyrin species.From the equilibrium and kinetic data, there was then calculated the second-order rate constants for oxygen atom transfer from YOOH compounds to the species (TPP)MnIIICl, TPP(Cl)MnIIIN, and TPP(Cl)MnIIIN2 (where N = ImH, N-MeIm, and 3,4-Py).Only the percarboxylic acids exhibit measurable rate constants for oxygen transfer to (TPP)MnIIICl, whereas alkyl hydroperoxides and percarboxylic acids transfer oxygen to the TPP(Cl)MnIIIN species.Of the species TPP(Cl)MnIIIN2, reaction with YOOH compounds is seen only when N is imidazole.This is attributed to an equilibrium of the unreactive bis axially ligated TPP(Cl)MnIII(ImH)2 with the reactive isomeric mono axial-ligated complex Cl(1-)...H-Im...H-Im...MnIIITPP.Nitrogen base ligation of (TPP)MnIIICl provides minimally a 1E3 increase in the rate constants for oxygen transfer in methylene chloride.Linear free-energy plots of the log of the second-order rate constants for oxygen transfer from YOOH vs. the pKa of YOH establish that β1g for oxygen transfer in which heterolytic O-O bond scission is rate-determining is large and negative.The value of β1g when oxygen transfer involves rate-determining homolytic O-O bond scission is small and negative.
- Yuan, Lung-Chi,Bruice, Thomas C.
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p. 1643 - 1650
(2007/10/02)
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- Direct Oxidation of Alkanoic Acids and their Amides to γ-Lactones by Peroxydisulphate-containing Systems
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The reaction of one-electron oxidation of alkanoic acids (I) and their amides (VI) on treatment with Na2S2O8-containing systems has been studied.As a result of the direct one-pot reaction acids (I) and amides (VI) are converted into γ and δ-lactones, the reaction being regioselective and leading mainly to γ-lactones in up to 35percent yield.The regioselectivity of the oxidative lactonisation depends greatly on the nature of alkyl substituents.The results obtained are presented in terms of a mechanism suggesting the generation of acyloxyl and amidyl radicals from (I) and (VI), respectively, followed by a rearrangement via a 1,5- or 1,6-H shift into the corresponding 3- and 4-carboxy- or -carboxamido-alkyl ra The latter undergo oxidative cyclisation to produce γ and δ lactones.The system Na2S2O8-NaCl-NaOH converts carboxamides (VI) into amines with loss of one carbon atom as a result of a Hoffmann type rearrangement.
- Nikishin, Gennady I.,Svitanko, Igor V.,Troyansky, Emmanuil I.
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p. 595 - 602
(2007/10/02)
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- Chlorination of Carboxylic Acid Derivatives. VIII. Liquid Phase Chlorination of the Aliphatic C5-Carboxylic Acids and Their Chlorides, Methyl Esters and Chloromethyl Esters with Chlorine
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The chlorination of pentanoic, 3-methylbutanoic, 2-methylbutanoic and 2,2-dimethylpropanoic acids and their derivatives with chlorine in the liquid phase have been investigated.The monochloro products formed were determined by gas-liquid chromatography (GLC) and gas-liquid chromatography-mass spectrometry (GLC-MS) as their esters through the comparison with authentic samples.The deactivation of position 2 decreases in the order COCl > CO2H > CO2CH2Cl > CO2CH3, the effect of the COCl-group in pentanoic acid derivatives being 4.3 times stronger than that of the CO2CH3-group.The deactivation is smallest in 2-methylbutanoic acid derivatives owing to the electron-donating methyl group.The EI mass spectra of the methyl and chloromethyl esters have been studied in detail.
- Kornonen, Ilpo O. O.
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p. 467 - 474
(2007/10/02)
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