- Practical and Selective sp3 C?H Bond Chlorination via Aminium Radicals
-
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
-
supporting information
p. 7132 - 7139
(2021/03/03)
-
- Experimental and theoretical studies of a greener catalytic system for saturated hydrocarbon chlorination composed by trichloroisocyanuric acid and a copper(II) compound
-
We are describing herein a new environmentally friendly catalytic system able to convert cyclohexane to chlorocyclohexane with 100% selectivity. The method was also applied to the chlorination of n-hexane and adamantane. The catalytic system employs thichloroisocyanuric acid (TCCA) as halogenating agent and a mononuclear copper(II) complex [Cu(BPAH)(H2O)](ClO4)2, 1, as catalyst (BPAH = 1,4-bis(propanamide)homopiperazine), whose molecular structure was solved by monocrystal X-ray diffraction. For cyclohexane, at a ratio catalyst:substrate:TCCA of 1:1000:333, the system reached a conversion of 32.0 ± 1% at 25 °C and 44.7 ± 0.4% at 50 °C, with 100% selectivity for chlorocyclohexane. With n-hexane, a similar conversion was observed at 50 °C, resulting in mixture of monochlorides. Employing adamantane as substrate, the isomers 1-chloroadamantane and 2-chloroadamante were preferentially formed, together with traces of dichloroadamantane. EPR and ESI-(+)-MS analyses indicate the formation of a Cu-hypochlorite intermediate species, which is supported by theoretical calculations.
- Melo, Isis L.,Lube, Leonardo M.,Neves, Eduardo S.,Terra, Wagner S.,Fernandes, Christiane,Matos, Carlos R.R.,Franco, Roberto W.A.,Resende, Jackson A.L.C.,Valente, Daniel C.A.,Horta, Bruno A.C.,Cardozo, Thiago M.,Horn, Adolfo
-
p. 150 - 158
(2018/06/14)
-
- Reagent-dictated site selectivity in intermolecular aliphatic C-H functionalizations using nitrogen-centered radicals
-
The site selectivities of intermolecular, aliphatic C-H bond functionalizations are central to the value of these transformations. While the scope of these reactions continues to expand, the site selectivities remain largely dictated by the inherent reactivity of the substrate C-H bonds. Herein, we introduce reagent-dictated site selectivity to intermolecular aliphatic C-H functionalizations using nitrogen-centered amidyl radicals. Simple modifications of the amide lead to high levels of site selectivity in intermolecular C-H functionalizations across a range of simple and complex substrates. DFT calculations demonstrate that the steric demand of the reacting nitrogen-centered radical is heavily affected by the substitution pattern of the starting amide. Optimization of transition state structures consistently indicated higher reagent-dictated steric selectivities using more hindered amides, consistent with experimental results.
- Carestia, Anthony M.,Ravelli, Davide,Alexanian, Erik J.
-
p. 5360 - 5365
(2018/06/27)
-
- Highly selective halogenation of unactivated C(sp3)-H with NaX under co-catalysis of visible light and Ag@AgX
-
The direct selective halogenation of unactivated C(sp3)-H bonds into C-halogen bonds was achieved using a nano Ag/AgCl catalyst at RT under visible light or LED irradiation in the presence of an aqueous solution of NaX/HX as a halide source, in air. The halogenation of hydrocarbons provided mono-halide substituted products with 95% selectivity and yields higher than 90%, with the chlorination of toluene being 81%, far higher than the 40% conversion using dichlorine. Mechanistic studies demonstrated that the reaction is a free radical process using blue light (450-500 nm), with visible light being the most effective light source. Irradiation is proposed to cause AgCl bonding electrons to become excited and electron transfer from chloride ions induces chlorine radical formation which drives the substitution reaction. The reaction provides a potentially valuable method for the direct chlorination of saturated hydrocarbons.
- Liu, Shouxin,Zhang, Qi,Tian, Xia,Fan, Shiming,Huang, Jing,Whiting, Andrew
-
p. 4729 - 4737
(2018/10/23)
-
- Mild Aliphatic and Benzylic Hydrocarbon C-H Bond Chlorination Using Trichloroisocyanuric Acid
-
We present the controlled monochlorination of aliphatic and benzylic hydrocarbons with only 1 equiv of substrate at 25-30 °C using N-hydroxyphthalimide (NHPI) as radical initiator and commercially available trichloroisocyanuric acid (TCCA) as the chlorine source. Catalytic amounts of CBr4 reduced the reaction times considerably due to the formation of chain-carrying ·CBr3 radicals. Benzylic C-H chlorination affords moderate to good yields for arenes carrying electron-withdrawing (50-85%) or weakly electron-donating groups (31-73%); cyclic aliphatic substrates provide low yields (24-38%). The products could be synthesized on a gram scale followed by simple purification via distillation. We report the first direct side-chain chlorination of 3-methylbenzoate affording methyl 3-(chloromethyl)benzoate, which is an important building block for the synthesis of vasodilator taprostene.
- Combe, Sascha H.,Hosseini, Abolfazl,Parra, Alejandro,Schreiner, Peter R.
-
p. 2407 - 2413
(2017/03/11)
-
- Visible Light-Induced Oxidative Chlorination of Alkyl sp3 C-H Bonds with NaCl/Oxone at Room Temperature
-
A visible light-induced monochlorination of cyclohexane with sodium chloride (5:1) has been successfully accomplished to afford chlorocyclohexane in excellent yield by using Oxone as the oxidant in H2O/CF3CH2OH at room temperature. Other secondary and primary alkyl sp3 C-H bonds of cycloalkanes and functional branch/linear alkanes can also be chlorinated, respectively, under similar conditions. The selection of a suitable organic solvent is crucial in these efficient radical chlorinations of alkanes in two-phase solutions. It is studied further by the achievement of high chemoselectivity in the chlorination of the benzyl sp3 C-H bond or the aryl sp2 C-H bond of toluene.
- Zhao, Mengdi,Lu, Wenjun
-
supporting information
p. 4560 - 4563
(2017/09/11)
-
- Site-Selective Aliphatic C-H Chlorination Using N-Chloroamides Enables a Synthesis of Chlorolissoclimide
-
Methods for the practical, intermolecular functionalization of aliphatic C-H bonds remain a paramount goal of organic synthesis. Free radical alkane chlorination is an important industrial process for the production of small molecule chloroalkanes from simple hydrocarbons, yet applications to fine chemical synthesis are rare. Herein, we report a site-selective chlorination of aliphatic C-H bonds using readily available N-chloroamides and apply this transformation to a synthesis of chlorolissoclimide, a potently cytotoxic labdane diterpenoid. These reactions deliver alkyl chlorides in useful chemical yields with substrate as the limiting reagent. Notably, this approach tolerates substrate unsaturation that normally poses major challenges in chemoselective, aliphatic C-H functionalization. The sterically and electronically dictated site selectivities of the C-H chlorination are among the most selective alkane functionalizations known, providing a unique tool for chemical synthesis. The short synthesis of chlorolissoclimide features a high yielding, gram-scale radical C-H chlorination of sclareolide and a three-step/two-pot process for the introduction of the β-hydroxysuccinimide that is salient to all the lissoclimides and haterumaimides. Preliminary assays indicate that chlorolissoclimide and analogues are moderately active against aggressive melanoma and prostate cancer cell lines.
- Quinn, Ryan K.,K?nst, Zef A.,Michalak, Sharon E.,Schmidt, Yvonne,Szklarski, Anne R.,Flores, Alex R.,Nam, Sangkil,Horne, David A.,Vanderwal, Christopher D.,Alexanian, Erik J.
-
supporting information
p. 696 - 702
(2016/02/03)
-
- Method of manufacturing imidoyl diazidosulfochloride compd. various compd. and manufacturing method of using the same
-
PROBLEM TO BE SOLVED: To provide a new production method for synthesizing an imidoyl chloride compound dispensing with chlorination agents having poor handleability, to provide a method for producing various compounds in high yield and purity by using the imidoyl chloride compound, and to provide a method for isolating the imidoyl chloride compound in high efficiency and purity from a mixture of the imidoyl chloride compound and a phthalic anhydride compound.SOLUTION: The method for producing the imidoyl chloride compound comprises reaction of a specific amide compound with a specific phthaloyl chloride compound to produce a specific imidoyl chloride compound.
- -
-
Paragraph 0040
(2016/12/16)
-
- Spectroscopic Analyses on Reaction Intermediates Formed during Chlorination of Alkanes with NaOCl Catalyzed by a Nickel Complex
-
The spectroscopic, electrochemical, and crystallographic characterization of [(Me,HPyTACN)NiII(CH3CN)2](OTf)2 (1) (Me,HPyTACN = 1-(2-pyridylmethyl)-4,7-dimethyl-1,4,7-triazacyclononane, OTf = CF3SO3) is described together with its reactivity with NaOCl. 1 catalyzes the chlorination of alkanes with NaOCl, producing only a trace amount of oxygenated byproducts. The reaction was monitored spectroscopically and by high resolution electrospray-mass spectrometry (ESI-MS) with the aim to elucidate mechanistic aspects. NaOCl reacts with 1 in acetonitrile to form the transient species [(L)NiII-OCl(S)]+ (A) (L = Me,HPyTACN, S = solvent), which was identified by ESI-MS. UV/vis absorption, electron paramagnetic resonance, and resonance Raman spectroscopy indicate that intermediate A decays to the complex [(L)NiIII-OH(S)]2+ (B) presumably through homolytic cleavage of the O-Cl bond, which liberates a Cl? atom. Hydrolysis of acetonitrile to acetic acid under the applied conditions results in the formation of [(L)NiIII-OOCCH3(S)]2+ (C), which undergoes subsequent reduction to [(L)NiII-OOCCH3(S)]2+ (D), presumably via reaction with OCl- or ClO2-. Subsequent addition of NaOCl to [(L)NiII-OOCCH3(S)]+ (D) regenerates [(L)NiIII-OH(S)]2+ (B) to a much greater extent and at a faster rate. Addition of acids such as acetic and triflic acid enhances the rate and extent of formation of [(L)NiIII-OH(S)]2+ (B) from 1, suggesting that O-Cl homolytic cleavage is accelerated by protonation. Overall, these reactions generate Cl? atoms and ClO2 in a catalytic cycle where the nickel center alternates between Ni(II) and Ni(III). Chlorine atoms in turn react with the C-H bonds of alkanes, forming alkyl radicals that are trapped by Cl? to form alkyl chlorides.
- Draksharapu, Apparao,Codolà, Zoel,Gómez, Laura,Lloret-Fillol, Julio,Browne, Wesley R.,Costas, Miquel
-
p. 10656 - 10666
(2015/11/27)
-
- Use of metal-accumulating plants for implementing chemical reactions
-
The use of metal-accumulating plants for implementing chemical reactions.
- -
-
Page/Page column 38-40
(2015/10/28)
-
- Chlorination of hydrocarbons with CCl4 catalyzed by complexes of Mn, Mo, V, Fe
-
Catalytic chlorination of alkanes, cycloalkanes, and adamantane utilizing tetrachloromethane as the source of chlorine and applying catalysts containing manganese, molybdenum, vanadium, and iron activated with nitrile ligands, alcohols, and water was fulfilled. The optimum ratios of catalysts and reagents and the best reaction conditions were found for selective synthesis of chlorine-substituted hydrocarbons derivatives. Pleiades Publishing, Ltd., 2013.
- Khusnutdinov,Shchadneva,Bayguzina,Oshnyakova,Mayakova,Dzhemilev
-
p. 1557 - 1566
(2014/02/14)
-
- 19F NMR of linear N,N-difluoroaminoalkanes
-
Whereas most N,N-difluoroaminoalkanes exhibit a single 19F resonance at about +50 ppm, the tri-component mixtures of both N,N-difluoroaminopentanes and N,N-difluoroaminohexanes exhibited a more complex pattern. The individual 1-N,N-difluoroamino-, 2-N,N-difluoroamino- and 3-N,N-difluoroaminopentanes have been synthesized and their separated resonances are reported.
- Belter, Randolph K.
-
body text
p. 73 - 76
(2012/05/07)
-
- The chemistry of cyclic carbaphosphazenes: The first observation of (R 2PN)(ClCN)2 (R=Cl, Ph) as a reagent for the conversion of alcohols to aldehydes, ketones, and alkyl chlorides
-
The oxidation of nine primary and secondary alcohols to the corresponding aldehydes and ketones has been carried out under mild conditions and in good yields using the cyclocarbaphosphazenes (R2PN)(ClCN)2 [R2P = Cl2 P(1), Ph2P(2)] along with dimethylsulfoxide. While both the P-Cl and C-Cl bonds of the carbaphosphazene can in principle bring about the reaction, we observed an increased preference for the C-Cl bonds over the P-Cl bonds in the oxidation of alcohol. Blocking the reactive P site on the heterocyclic ring with the phenyl groups was found to reduce the yields of the oxidized products, while blocking the C- sites with diethylamino groups resulted in no reaction. In addition, along with DMF, the same cyclocarbaphosphazene has been found to be useful for the conversion of alcohols to alkyl chlorides. Copyright Taylor & Francis Group, LLC.
- Behera, Nabakrushna,Mishra, Pradyumna Kumar,Elias, Anil J.
-
p. 2445 - 2452
(2007/10/03)
-
- Reactivity of bismuth(III) halides towards alcohols. A tentative to mechanistic investigation
-
The reactivity of bismuth(III) halides (BiX3; X=Cl, Br and I) towards a series of alcohols has been investigated. Three different reactions have been studied, namely: halogenation, dehydration and etherification. The behaviour of these bismuth derivatives was found to depend on the nature of the halide bonded to the bismuth atom. Their reactivities can be interpreted on the basis of the Hard and Soft Acids and Bases (HSAB) principle. A mechanism is proposed which involves the formation of a complex of the alcohol with Bi(III).
- Keramane, El Mehdi,Boyer, Bernard,Roque, Jean-Pierre
-
p. 1909 - 1916
(2007/10/03)
-
- BiX3 as an efficient and selective reagent for the halogen exchange reaction
-
Bismuth halides are efficient and selective reagents in the halogen exchange reactions carried out under mild conditions. This rapid, high yield reaction proceeds mainly with retention of configuration.
- Boyer, Bernard,Keramane, El Mehdi,Arpin, Severine,Montero, Jean-Louis,Roque, Jean-Pierre
-
p. 1971 - 1976
(2007/10/03)
-
- Preparative catalytic chlorination of adamantane, cyclohexane, and hexane in the system tetrachloromethane-MX2(PPh3)2 (MX2 = PdBr2, PtCl2)-acetonitrile-potassium carbonate
-
Heating of saturated hydrocarbons RH (cyclohexane, adamantane, and hexane) with tetrachloromethane in the presence of acetonitrile, potassium carbonate, and catalytic amounts of dihalide triphenylphosphine complexes of palladium(II) or platinum(II), MX2(PPh)2 (MX2 = PdBr2, PtCi2), for 6-8 h at 120°C yields monochlorinated derivatives of the respective hydrocarbons in 30-55% yield. Benzene, toluene, ethylbenzene, and tetramethylsilane show low reactivity under the conditions adopted for the reaction. Relative reactivity of various bond types C-H of alkanes is in agreement with the well known sequence: tertiary > secondary > primary. A scheme is proposed assuming trichloromethyl radicals as active species, and the catalyst function consists in activating C-C1 bond of the tetrachloromethane.
- Vedernikov,Sayakhov,Zazybin,Solomonov
-
p. 812 - 815
(2007/10/03)
-
- Acidity effect in the regiochemical control of the alkylation of phenol with alkenes
-
Treatment of 1:1 mixtures of phenol and linear alkenes in the presence of an acidic promoter in CHCl3 at room temperature results in ortho-regioselective monoalkylation producing sec-alkylphenols in 48-60% yield. In similar reactions, branched alkenes lead exclusively to the corresponding para-tert-alkylphenols in 80-85% yield. Addition of increasing amounts of potassium phenolate to the reacting system reduces the protic acidity and promotes ortho-regioselective tert-alkylation. These results are tentatively explained in terms of competition of 'H-bond-template' and 'charge-controlled' mechanisms.
- Sartori, Giovanni,Bigi, Franca,Maggi, Raimondo,Arienti, Attilio
-
p. 257 - 260
(2007/10/03)
-
- New Catalytic System for Activation of Alkane and Arene C-H Bonds on the Basis of Platinum(II) Complexes and Tetrachloromethane
-
Alkanes and alkylarencs RH (cyclohexane, n-hexane, toluene) in a mixture with CCl4 and MeCN (1:1:1, by volume), at temperatures of 110°C and higher, in the presence of platinum complexes of the formula cis-PtX2(L)2 (X = Cl, Ph, L = PPh3; X = Cl, L = MeCN), react to form chloroform and chloride RCl. Catalytic activity decreases in the order PtPh2(PPh3)2 (3.9) > PtCl2(PPh3)2 (1.0) > PtCl2(MeCN)2 (0.24). In the case of n-hexane, C-H bonds at the secondary carbon atoms are by a factor of 11 more active than those at the primary atom, and in the case of toluene, benzyl chloride is the main reaction product (99%). The reaction is first-order in cyclohexane, metal complex, and tetrachloromethane. The chlorination of toluene is zero-order in hydrocarbon. The results of kinetic studies permit to conclude that the role of the catalyst is to activate the tetrachloromethane C-Cl bonds by an oxidative addition scheme.
- Vedernikov,Zazybin,Borisoglebskii,Solomonov
-
p. 1922 - 1924
(2007/10/03)
-
- Trimethylchlorosilane and water. Convenient reagents for the regioselective hydrochlorination of olefins
-
The hydrochlorination of a series of simple and functionalized olefins in high yields was readily accomplished using a mixture of trimethylchlorosilane and water. Hydrochlorination by this procedure is chemoselective and regioselective.
- Boudjouk, Philip,Kim, Beon-Kyu,Han, Byung-Hee
-
p. 3479 - 3484
(2007/10/03)
-
- Intramolecular H-Transfer Reactions During the Decomposition of Alkylhydroperoxides in Hydrocarbons as the Solvents
-
Eight defined primary and secondary alkylhydroperoxides were decomposed in n-alkanes as the solvent, mostly in the presence of manganese stearate.In all cases the corresponding alcohols and carbonyl compounds were formed as the main products with yields of 60-90percent.Besides, difunctional products were formed by an intramolecular H-transfer in the alkoxy radicals corresponding to the starting hydroperoxides.Products possibly formed by an intramolecular H-transfer in the corresponding alkylperoxy radical could be found only in the case of 4-methyl-2-hydroperoxy pentane.The amount of products formed by intramolecular H-transfer depended on the nature of the C-H bond in δ-position to the original hydroperoxy group and lay between 4percent (primary C-H in the case of 4-hydroperoxy heptane) and 13percent (tertiary C-H in the case of 2-hydroperoxy-5-methyl hexane) with respect to the starting hydroperoxide.The amount of products formed by oxidative attack of the alkoxy and alkylperoxy radicals at the normal paraffins used as the solvents was unexpectedly low (always less than 10percent with respect to the starting hydroperoxide).An increment system is proposed for the calculation of 13C-nmr shifts in alkyl hydroperoxides.
- Jinsheng, Li,Pritzkow, Wilhelm,Voerckel, Volkmar
-
-
- Cobalt(II)-Porphyrin Catalyzed Selective Functionalization of Alkanes with sulfurylchloride: A Remarkable Substituent Effect
-
Cobalt(II)-porphyrin complex 1 and 2 catalyses the chlorination and sulfochlorination respectively of n-alkanes and cycloalkanes with sulfuryl chloride in benzene.The p-substituent of the benzene ring in the porphyrin complex 1 and 2 shows a remarkable chemoselectivity in these reactions.
- Khanna, Vibha,Tamilselvan, Pitchiah,Kalra, Swinder Jeet Singh,Iqbal, Javed
-
p. 5935 - 5938
(2007/10/02)
-
- HYDROCHLORINATION OF UNSATURATED COMPOUNDS BY THE ACTION OF CH2Cl2 OR CHCl3 AND RHODIUM COMPLEXES
-
A new method has been developed for the catalytic hydrochlorination of olefins and acetylenes in the presence of Rh complexes by means of HCl generated in situ from CH2Cl2 and CHCl3 under the reaction conditions.The reaction was studied using the hydrochlorination of propylene, 1-hexene, 1-nonene, vinylcyclopropane, 1,1-dicyclopropylethylene, cyclohexene, cyclooctene, norbornene, and 1,5-cyclooctadiene as examples.
- Khusnutdinov, R. I.,Shchadneva, N. A.,Dzhemilev, U. M.,Tolstikov, G. A.
-
p. 1213 - 1217
(2007/10/02)
-
- FREE RADICAL HALOGENATION OF ALKANES INITIATED BY TRANSITION METAL COMPLEXES
-
Reaction between halocarbons (particularly CCl4) and hydrocarbons (particularly c-C6H12) in the presence of a range of low valent metal complexes have been investigated.A delaited study of the reaction involving has shown it to proceed by a free radical chain route in which the metal complex acts solely as an initiator.Similar behaviour has been confirmed for . (Re2(CO)10> and show initiation efficiencies comparable with organic peroxides, but other complexes are less efficient.Factors effecting efficiencies have been studied.
- Davis, Reg,Durrant, Jim L. A.,Rowland, Christopher C.
-
p. 147 - 162
(2007/10/02)
-
- Carbon-13 Nuclear Magnetic Resonance of Mono- and Di-chloro-hexanes and Mono- and Di-chloro-heptanes. Assignment of Configurations
-
Carbon-13 NMR spectra of mono- and dichloro-hexanes and mono- and dichloro-heptanes are reported.Substituent effects for α, β and γ positions are presented.Differences between the 13C chemical shifts of diastereoisomers are observed in the cases of 2,4- and 2,5-dichlorohexanes and 2,4-, 2,5- and 3,5-dichloroheptanes.
- Nouguier, R.,Surzur, J.-M.,Virgili, A.
-
p. 155 - 157
(2007/10/02)
-
- Selectivity in the Halogenation of Hexane by Tertiary Aminium Radicals from the Photodecomposition of N-Halogenoammonium Perchlorates
-
The photochlorination of hexane with tertiary N-chloroammonium perchlorates in trifluoroacetic acid gives monochlorohexanes in high yield and with a striking preference for the 2-isomer.It is shown that free-radical chains are involved in which hydrogen-atom abstraction is by tertiary aminium radicals.The marked preference for 2- compared with 3-chlorination is attributed mainly to the bulky aminium radical attacking the relatively more accessible 2-position; an alternative explanation involving a reversible hydrogen-atom abstraction is ruled out.The magnitude of the primary deuterium kinetic isotope effect in these photochlorinations gives information about the dependence of the extent of C-H bond breakage in the transition state on the structure of the abstracting aminium radical.
- Fuller, Steven E.,Smith, John R. Lindsay,Norman, Richard O. C.,Higgins, Raymond
-
p. 545 - 552
(2007/10/02)
-