- p-Fluorobenzaldehyde and p-fluorobenzoic acid by oxidation of p-fluorobenzyl derivatives
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Experiments on the oxidation reactions of p-fluorobenzyl alcohol and chloride were carried out. Several oxidizing agents (manganese dioxide, 30% hydrogen peroxide and hypochlorite solutions at different concentrations) were used, and a mixture of p-fluorobenzaldehyde and p-fluorobenzoic acid in different proportions was obtained. In the case of p-fluorobenzyl chloride, some p-fluorobenzyl alcohol was also found in the reaction mixture. The experimental conditions required to obtain an increase in the yield of the aldehyde or acid were also studied.
- Conte,Napoli,Gambaretto,Carlini,Bonini
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Read Online
- One-Pot Deoxygenation and Substitution of Alcohols Mediated by Sulfuryl Fluoride
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Sulfuryl fluoride is a valuable reagent for the one-pot activation and derivatization of aliphatic alcohols, but the highly reactive alkyl fluorosulfate intermediates limit both the types of reactions that can be accessed as well as the scope. Herein, we report the SO2F2-mediated alcohol substitution and deoxygenation method that relies on the conversion of fluorosulfates to alkyl halide intermediates. This strategy allows the expansion of SO2F2-mediated one-pot processes to include radical reactions, where the alkyl halides can also be exploited in the one-pot deoxygenation of primary alcohols under mild conditions (52-95% yield). This strategy can also enhance the scope of substitutions to nucleophiles that are previously incompatible with one-pot SO2F2-mediated alcohol activation and enables substitution of primary and secondary alcohols in 54-95% yield. Chiral secondary alcohols undergo a highly stereospecific (90-98% ee) double nucleophilic displacement with an overall retention of configuration.
- Epifanov, Maxim,Mo, Jia Yi,Dubois, Rudy,Yu, Hao,Sammis, Glenn M.
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p. 3768 - 3777
(2021/03/01)
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- Hydrogen Bond Directed Photocatalytic Hydrodefluorination and Methods of Use Thereof
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Methods of synthesizing compounds comprising fluorinated aryl groups are disclosed, wherein said methods utilize hydrogen bond directed photocatalytic hydrodefluorination.
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Paragraph 0203
(2021/01/22)
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- N -Hydroxyphthalimide/benzoquinone-catalyzed chlorination of hydrocarbon C-H bond using N -chlorosuccinimide
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The direct chlorination of C-H bonds has received considerable attention in recent years. In this work, a metal-free protocol for hydrocarbon C-H bond chlorination with commercially available N-chlorosuccinimide (NCS) catalyzed by N-hydroxyphthalimide (NHPI) with 2,3-dicyano-5,6-dichlorobenzoquinone (DDQ) functioning as an external radical initiator is presented. Aliphatic and benzylic substituents and also heteroaromatic ones were found to be well tolerated. Both the experiments and theoretical analysis indicate that the reaction goes through a process wherein NHPI functions as a catalyst rather than as an initiator. On the other hand, the hydrogen abstraction of the C-H bond conducted by a PINO species rather than the highly reactive N-centered radicals rationalizes the high chemoselectivity of the monochlorination obtained by this protocol as the latter is reactive towards the C(sp3)-H bonds of the monochlorides. The present results could hold promise for further development of a nitroxy-radical system for the highly selective functionalization of the aliphatic and benzylic hydrocarbon C-H.
- Li, Zi-Hao,Fiser, Béla,Jiang, Biao-Lin,Li, Jian-Wei,Xu, Bao-Hua,Zhang, Suo-Jiang
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supporting information
p. 3403 - 3408
(2019/04/01)
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- Synthesis of mono- and difluorobenzyl chlorides by chlorination of mono- and difluorotoluenes with CCl4 and t-BuOCl induced by iron-containing catalysts
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Mono- and difluorobenzyl chlorides were synthesized by chlorination of mono- and difluorotoluenes with CCl4?MeOH or t-BuOCl in the presence of iron-containing catalysts.
- Bayguzina, Alfiya R.,Gallyamova, Leysan I.,Khalilov, Leonard M.,Khusnutdinov, Ravil I.
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supporting information
(2019/07/19)
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- α-Diimine-Niobium Complex-Catalyzed Deoxychlorination of Benzyl Ethers with Silicon Tetrachloride
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α-Diimine niobium complexes serve as catalysts for deoxygenation of benzyl ethers by silicon tetrachloride (SiCl4) to cleanly give two equivalents of the corresponding benzyl chlorides, where SiCl4 has the dual function of oxygen scavenger and chloride source with the formation of a silyl ether or silica as the only byproduct. The reaction mechanism has two successive trans-etherification steps that are mediated by the niobium catalyst, first forming one equivalent of benzyl chloride along with the corresponding silyl ether intermediate that undergoes the same reaction pathway to give the second equivalent of benzyl chloride and silyl ether.
- Parker, Bernard F.,Hosoya, Hiromu,Arnold, John,Tsurugi, Hayato,Mashima, Kazushi
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supporting information
p. 12825 - 12831
(2019/10/19)
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- Highly selective halogenation of unactivated C(sp3)-H with NaX under co-catalysis of visible light and Ag@AgX
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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
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p. 4729 - 4737
(2018/10/23)
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- SNAr catalysis enhanced by an aromatic donor-acceptor interaction; Facile access to chlorinated polyfluoroarenes
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Selective catalytic SNAr reaction of polyfluoroaryl C-F bonds with chloride is shown. Stoichiometric TMSCl makes the reaction exergonic and allows catalysis, which involves ground state elevation of chloride, aromatic donor-acceptor interactions, and stabilization of the Meisenheimer complex. Traditional cross-coupling of the products is now possible and demonstrates the utility.
- Senaweera, Sameera,Weaver, Jimmie D.
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supporting information
p. 7545 - 7548
(2017/07/12)
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- Formamides as Lewis Base Catalysts in SNReactions—Efficient Transformation of Alcohols into Chlorides, Amines, and Ethers
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A simple formamide catalyst facilitates the efficient transformation of alcohols into alkyl chlorides with benzoyl chloride as the sole reagent. These nucleophilic substitutions proceed through iminium-activated alcohols as intermediates. The novel method, which can be even performed under solvent-free conditions, is distinguished by an excellent functional group tolerance, scalability (>100 g) and waste-balance (E-factor down to 2). Chiral substrates are converted with excellent levels of stereochemical inversion (99 %→≥95 % ee). In a practical one-pot procedure, the primary formed chlorides can be further transformed into amines, azides, ethers, sulfides, and nitriles. The value of the method was demonstrated in straightforward syntheses of the drugs rac-Clopidogrel and S-Fendiline.
- Huy, Peter H.,Motsch, Sebastian,Kappler, Sarah M.
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supporting information
p. 10145 - 10149
(2016/08/16)
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- METHOD OF CONVERTING ALCOHOL TO HALIDE
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The present invention relates to a method of converting an alcohol into a corresponding halide. This method comprises reacting the alcohol with an optionally substituted aromatic carboxylic acid halide in presence of an N-substituted formamide to replace a hydroxyl group of the alcohol by a halogen atom. The present invention also relates to a method of converting an alcohol into a corresponding substitution product. The second method comprises: (a) performing the method of the invention of converting an alcohol into the corresponding halide; and (b) reacting the corresponding halide with a nucleophile to convert the halide into the nucleophilic substitution product.
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Page/Page column 96; 97
(2017/01/02)
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- Pd-catalyzed cyanation of benzyl chlorides with nontoxic K 4[Fe(CN)6]
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Non-toxic K4[Fe(CN)6] was demonstrated to be effective as a green cyanating agent for the cyanation of alkyl halides using PPh3/Pd(OAc)2 as a catalyst system. The presented method allowed a series of benzyl chlorides to be smoothly cyanated in up to 88% yield. In order to avoid or suppress the deactivation of the catalyst, the reaction was required to be performed in a stringent inert ambiance.
- Ren, Yunlai,Yan, Mengjie,Zhao, Shuang,Sun, Yanpei,Wang, Jianji,Yin, Weiping,Liu, Zhifei
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supporting information; body text
p. 5107 - 5109
(2011/10/05)
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- Kinetics and Equilibria of Chloride Transfer Reactions. Stabilities of Carbocations Based on Chloride and Hydride Transfer Equilibria Measurements
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The kinetics of a number of gas-phase chloride transfer reactions R0(1+)+RCl=R0Cl+R(1+) were measured with a pulsed electron high pressure mass spectrometer.Most of the reactions were found to occur near the collision limit, i.e., with rate constants k ca. 10-9 molecules-1 cm3 s-1.However, several reactions were much slower and were exhibiting negative temperature dependence, i.e., decreasing rate with increasing temperature.Hydride and chloride transfer equilibria were determined for various carbocations R(1+) (R=isopropyl, cyclopentyl, tert-butyl, 1-methylcyclopentyl, substituted benzyls, norbornyl, 2-methyl-2-norbornyl, and adamantyl).Excellent agreement with earlier hydride transfer measurements of Solomon, Meot-Ner, and Field were observed.The chloride affinities generally support conclusions based on the hydride transfer data.Discussion of the data in connection with benzyl cation substituent effects, the norbornyl cation stability, and solvent effects on carbocation stability is presented.The data show that the 2-norbornyl cation is unusually stable.Significant differences between carbocation R(1+) stabilities in gas phase and solution are found which suggest that both differential nucleophilic solvent stabilization and differential nonspecific solvation occur in solution.
- Sharma, R. B.,Sharma, D. K. Sen,Hiraoka, K.,Kebarle, P.
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p. 3747 - 3757
(2007/10/02)
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