Substituent effects on reductive cleavage of N-methylarenesulfonanilides. Cleavage by sodium anthracene and electrochemically at the vitreous carbon electrode

Quaal, K. S.; Ji, Sungchul; Kim, Young Beom; Closson, W. D.; Zubieta, Jon

doi:10.1021/jo00401a005

Cited by 39 publications

(8 citation statements)

References 6 publications

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“…214−216 They are also relevant as protecting groups in synthetic chemistry since the sulfonyl group can be easily removed when bound to nitrogen, allowing the N-alkylated sulfonamides to be rapidly converted into the corresponding primary amines. 217 Typically, the classical processes for synthesizing N-alkylated sulfonamides are performed by reacting amines and sulfonyl halides or sulfonic acids activated by triphenylphosphine distriflate, as well as through the reductive amination of aldehydes. 218 However, these previous processes have the inconveniences of giving secondary products and/or the need for sensitive substrates.…”

Section: Chemical Reviewsmentioning

confidence: 99%

“…Taking into account that the sulfonamide group can be easily removed as the protecting group, 217 different in situ deprotection protocols have been studied with the resulting sulfonamides and different catalysts. We will include an interesting and representative example that has been mentioned in a previous specific review.…”

Section: Chemical Reviewsmentioning

confidence: 99%

“…332 As it has been already shown in the previous section devoted to homogeneous catalysis, ammonia has been successfully replaced in numerous examples by other alternative chemical sources, and these concerns have also reached to heterogeneous catalysis. In this case, one of the first examples reported by the group of Mizuno studied the synthesis of both secondary and tertiary amines (218,219) from alcohols (13a, 26a) and urea (217), albeit this time in the presence of a recoverable heterogeneous ruthenium catalyst. 333 The relatively wide scope of this catalytic system was evidenced by the transformation of primary alcohols into tertiary amines, whereas other more hindered alcohols (secondary alcohols) were converted into secondary amines (Scheme 68) 333 in both cases using an alcohol excess.…”

Section: Activation Of Alcoholsmentioning

confidence: 99%

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Advances in One-Pot Synthesis through Borrowing Hydrogen Catalysis

2018

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The borrowing hydrogen (BH) principle, also called hydrogen auto-transfer, is a powerful approach which combines transfer hydrogenation (avoiding the direct use of molecular hydrogen) with one or more intermediate reactions to synthesize more complex molecules without the need for tedious separation or isolation processes. The strategy which usually relies on three steps, (i) dehydrogenation, (ii) intermediate reaction, and (iii) hydrogenation, is an excellent and well-recognized process from the synthetic, economic, and environmental point of view. In this context, the objective of the present review is to give a global overview on the topic starting from those contributions published prior to the emergence of the BH concept to the most recent and current research under the term of BH catalysis. Two main subareas of the topic (homogeneous and heterogeneous catalysis) have been identified, from which three subheadings based on the source of the electrophile (alkanes, alcohols, and amines) have been considered. Then the type of bond being formed (carbon-carbon and carbon heteroatom) has been taken into account to end-up with the intermediate reaction working in tandem with the metal-catalyzed hydrogenation/dehydrogenation step. The review has been completed with the more recent advances in asymmetric catalysis using the BH strategy.

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Section: Chemical Reviewsmentioning

confidence: 99%

Section: Chemical Reviewsmentioning

confidence: 99%

Section: Activation Of Alcoholsmentioning

confidence: 99%

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Advances in One-Pot Synthesis through Borrowing Hydrogen Catalysis

2018

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“…However, the reduction of 4-nitrobenzenesulfonamide and N-methyl-4-nitrobenzenesulfonamide was shown to occur by a disproportionation process involving the loss of hydrogen. On the other hand, the electrochemical reduction of N-methyl-4-nitrobenzenesulfonanilide reported by Quaal et al [6] showed an irreversible twoelectron process, in which subsequent cleavage of the S-N bond leads to a high yield of free amine.…”

Section: Introductionmentioning

confidence: 97%

Electrochemical behavior of aromatic amines protected by the nitrobenzenesulfonyl group

Zanoni

Stradiotto

1995

Electroanalysis

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The electrochemical reduction of aniline protected by the 4-, 3-, or 2-nitrobenzenesulfonyl group in N, N-dimethylformamide (DMF) at a vitreous carbon electrode is reported. The compouads are reduced in three cathodic steps. The first reduction step at about -0.85 V vs. SCE occurs with the formation of an unstable anion radical, which decomposes via N-H bond cleavage. Reduction of this sulfonamide anion occurs at -1.16V for para and meta isomers and at -1.48V for the ortho isomer. The third cathodic step occurs at higher cathodic potentials. The B-H bond cleavage is always the preponderant process. The mechanisms of the reduction are discussed.

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“…This group also modifies the polarity of the protected compound by withdrawing electrons. The methods for its deprotection are well known: dissolving metal reductions (Li or Na) in ammonia, HMPA, or alcohol; 6,7 sodium naphthalene 8 or anthracene, 9 Na-Hg, 10 Bu 3 SnH, 11,12 mischmetal with TiCl 4 , 13 SmI 2 , 14 Mg/ MeOH, 15,16 alkali metals in silica gel; 17 severe acidic conditions with H 2 SO 4 , 18 AcOH-HClO 4 , 19 48% HBr with PhOH and 30% HBr in AcOH, 20 KF on alumina under microwaves; 21 or basic conditions such as NaOH and KOH, 22,23 K 2 CO 3 in a acetonitrile, 24,25 Cs 2 CO 3 in THF-MeOH, 26 n-Bu 4 NF in refluxing THF. [27][28][29] Most of these methods are effective in a number of cases, but are not compatible with other groups.…”

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Desulfonylation of Indoles and 7-Azaindoles Using Sodium tert-Butoxide

Chaulet¹,

Croix²,

Basset³

et al. 2010

Synlett

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A mild method for the desulfonylation of N-indoles and N-azaindoles is described. Deprotection is carried out under basic conditions, using sodium tert-butoxide in dioxane. Several functionalized indoles and 7-azaindoles were efficiently deprotected by this method, which is mild enough to be used to deprotect compounds including functions that are known to be sensitive to acidic or basic conditions. Indoles and related structures are found in many active pharmaceutical molecules. [1][2][3][4][5] The NH group needs to be protected during synthetic pathways by a suitable group that can easily be removed at the end of the synthesis. The benzenesulfonyl group is one of the blocking groups commonly used to protect amines, because the resultant sulfonamides are more robust, confer crystallinity, and facilitate isolation. This group also modifies the polarity of the protected compound by withdrawing electrons. The methods for its deprotection are well known: dissolving metal reductions (Li or Na) in ammonia, HMPA, or alcohol; 6,7 sodium naphthalene 8 or anthracene, 9 Na-Hg, 10 Bu 3 SnH, 11,12 mischmetal with TiCl 4 , 13 SmI 2 , 14 Mg/ MeOH, 15,16 alkali metals in silica gel; 17 severe acidic conditions with H 2 SO 4 , 18 AcOH-HClO 4 , 19 48% HBr with PhOH and 30% HBr in AcOH, 20 KF on alumina under microwaves; 21 or basic conditions such as NaOH and KOH, 22,23 K 2 CO 3 in a acetonitrile, 24,25 Cs 2 CO 3 in THFMeOH, 26 n-Bu 4 NF in refluxing THF. [27][28][29] Most of these methods are effective in a number of cases, but are not compatible with other groups. We tried several of the methods described in the literature, but none of them gave satisfactory results.In a previous study, we were interested in the synthesis of compound 2. Treating 1-(phenylsulfonyl)-1H-pyrrolo[2,3-b]pyridine-2-carboxylic acid (1) in the presence of K 2 CO 3 refluxing in a MeOH-H 2 O mixture 30 or using an aqueous solution of NaOH reflux in EtOH 31 led to degradation products. Moreover, observed desulfonylation instead of introduction of an amine into position 2 during attempted Buchwald-type coupling of 2-iodo-1-(phenylsulfonyl)-1H-pyrrolo[2,3-b]pyridine 3 with aryl or alkylamines.This unexpected result has led us to develop a new and mild method to cleave the benzenesulfonyl moiety from protected indoles and related structures using sodium tertbutoxide. In order to determine the optimum stoichiometry, we carried out a series of experiments with 1-(phenylsulfonyl)-1H-pyrrolo[2,3-b]pyridine-2-carboxylic acid (1).The amount of sodium tert-butoxide and the heating method (sealed tube or flask) were studied. The best results were obtained with the addition of 1.5 equivalents of sodium tert-butoxide and heating in a sealed tube at 80°C for three hours. Under these conditions, the derivative 2 was isolated with 92% yield.Under these new optimized conditions, 32 a variety of substituted indoles and azaindoles was subjected to N-desulfonylation with NaOt-Bu in dioxane. The results are shown in Table 1.The desulfonylation of unsubstituted N-sulfonyl-7-aza...

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Substituent effects on reductive cleavage of N-methylarenesulfonanilides. Cleavage by sodium anthracene and electrochemically at the vitreous carbon electrode

Cited by 39 publications

References 6 publications

Advances in One-Pot Synthesis through Borrowing Hydrogen Catalysis

Advances in One-Pot Synthesis through Borrowing Hydrogen Catalysis

Electrochemical behavior of aromatic amines protected by the nitrobenzenesulfonyl group

Desulfonylation of Indoles and 7-Azaindoles Using Sodium tert-Butoxide

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