Silver-Promoted Decarboxylative Sulfonylation of Aromatic Carboxylic

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Silver-Promoted Decarboxylative Sulfonylation of Aromatic Carboxylic Acids with Sodium Sulfinates Yongqi Yu, Qianlong Wu, Da Liu, Lin Yu, Ze Tan, and Gangguo Zhu J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.joc.9b01333 • Publication Date (Web): 13 Aug 2019 Downloaded from pubs.acs.org on August 13, 2019

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The Journal of Organic Chemistry

Silver-Promoted Decarboxylative Sulfonylation of Aromatic Carboxylic Acids with Sodium Sulfinates Yongqi Yu,† Qianlong Wu,† Da Liu,† Lin Yu,† Ze Tan,†,* and Gangguo Zhu‡ †

State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, P. R. China

‡

Department of Chemistry, Zhejiang Normal University, 688 Yingbin Road, Jinhua 321004, China [email protected]

A novel and efficient synthesis of sulfones was developed via silver-promoted decarboxylative sulfonylation reaction between aromatic carboxylic acids and sodium sulfinates for the first time. The approach features operational simplicity, good functional group compatibility as well as using readily available starting materials. Furthermore, mechanistic studies reveal that the decarboxylative sulfonylation reaction is likely to proceed via a radical mechanism. Sulfones are a highly valuable class of organic molecules because of their unique bioactivity and chemical properties.1 They are widely present in various functional materials and pharmaceutical molecules (Figure 1).2 Moreover, these compounds are also important intermediates in organic transformations such as Smiles rearrangement3 and Julia olefination.4 Due to their importance, chemists have developed numerous methods for the synthesis of sulfones.5 Conventionally, they are prepared by the oxidation of sulfides,6 the sulfonylation of arenes with sulfonyl halides or their derivatives,7 or transition metal-catalyzed cross-coupling reactions between sulfinic acid salts and aryl halides.8 Recently, approaches based on the insertion of sulfur dioxide for the synthesis of sulfones have also been reported.9 Despite their usefulness, these methods tend to suffer from drawbacks such as the use of foul-smelling sulfides, harsh reaction conditions, requiring prefunctionalized starting materials or the generation of massive amount of useless by-products. As a consequence, developing efficient and straightforward strategies for the synthesis of sulfones from readily available starting materials is highly desirable.

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Figure 1. Biologically active aryl sulfones. Over the past several years, decarboxylative cross-coupling of aromatic carboxylic acids has emerged as a powerful tool in organic synthesis10 since various aryl carboxylic acids are inexpensive, readily available, chemically nontoxic and easy to store and handle. Early reports by the groups of Gooßen,11 Su,12 Myers,13 and others14 have shown that benzoic acid derivatives could undergo decarboxylative couplings to construct new C–C and C–X (X=S, O, N, etc.) bonds. It is commonly believed that aryl-metal intermediates are generated in situ by loss of CO2 from metal carboxylates. The resultant aryl organometallic species subsequently can be subjected to further functionalizations to give various coupling products. In these cases, either Pd/Cu or Pd/Ag bimetallic catalytic systems are often used for the decarboxylative couplings.15 Furthermore, copper-only systems for decarboxylative couplings have also been reported recently.14b,16 In contrast, silver-catalyzed or promoted decarboxylative coupling of aromatic carboxylic acids has been less explored and only a few reports have been documented so far.12b,17 In 2012, Greaney reported a silver-catalyzed intramolecular decarboxylative arylation reaction of benzoic acids to form fluorenones.17a In 2015, Su reported the synthesis of biaryl compounds via an intermolecular Minisci reaction of aromatic carboxylic acids with (hetero)arenes catalyzed by a Ag2SO4/K2S2O8 system.12b Later on, Natarajan reported a Ag2CO3-promoted ipso-nitration reaction of aromatic and aliphatic carboxylic acids by employing NO2BF4 as the nitrating agent.17b Driven by our interest in decarboxylative cross-couplings,18 we launched a research towards the synthesis of sulfones. A closer survey of literature reveals that decarboxylative sulfonylation of cinnamic acids and propiolic acids has been reported by several groups,19 however, decarboxylative sulfonylation of aromatic carboxylic acids remains unprecedented. Herein, we report the first example of silver-promoted decarboxylative sulfonylation reaction of aromatic carboxylic acids with sodium sulfinates. Table 1. Optimization of the Reaction Conditionsa


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a

Unless otherwise noted, the reactions were performed using 1a (0.3 mmol), 2a (2.0 equiv), Ag

salt (1.0 equiv), ligand (40 mol %) and Na2CO3 (2.0 equiv) in a solvent (3.0 mL) at 160 oC for 18 h under O2 in sealed tubes. bIsolated yield. NR = no reaction. ND = not detected. cCuCl2 (0.06 mmol) was added. dWithout Na2CO3. eUnder N2 atmosphere. fUnder air atmosphere. gK2S2O8 (0.6 mmol) was added. Our investigation commenced by choosing 2-nitrobenzoic acid (1a) and sodium 4-methylbenzenesulfinate (2a) as the model substrates. When the reaction mixture of 1a (0.3 mmol), 2a (0.6 mmol), CuCl2 (0.06 mmol), Ag2CO3 (0.3 mmol), 1,10-phenanthroline (0.12 mmol) and Na2CO3 (0.6 mmol) in toluene (3.0 mL) was stirred at 160 oC under O2 for 18 h, 51% yield of the desired decarboxylative sulfonylation product 3aa was isolated (Table 1, entry 1). To our surprise, when the model reaction was performed in the absence of CuCl2, the desired product 3aa could be isolated in 57% yield (Table 1, entry 2). Several commonly used silver salts such as AgNO3, AgOAc and Ag2O were subsequently explored, however no further improvement was observed (Table 1, entries 3–5). Control experiments showed that silver salt is essential for the transformation to proceed (Table 1, entry 6). The use of 2,2′-bipyridine in place of 1,10-phenanthroline resulted in lower yield (Table 1, entry 7). It should be noted that no desired product was detected when the model reaction was carried out with triphenylphosphine as the ligand or in the absence of the ligand (Table 1, entries 8, 9). Interestingly, an even better result was obtained when the reaction was performed in the absence of Na2CO3 (Table 1, entry 10). When the reaction was carried out under N2 atmosphere, a comparable yield was obtained (Table 1, entry 10



vs. entry 11), suggesting that O2 is not essential for the reaction. It was observed that the yield of 3aa could be improved further to 62% if the reaction was conducted under an air atmosphere (Table 1, entry 12). Subsequent solvent screening revealed that PhCF3 was the most efficient medium for the reaction (Table 1, entries13–15). We suspected that in polar solvents such as DMF and DMSO, protodecarboxylation is too fast and it became the main reaction pathway. With a slight increase in the loading of silver salt from 1.0 equiv to 1.5 equiv, the yield of 3aa was increased to 74% (Table 1, entries 16, 17). Moreover, we attempted to conduct the reaction in the presence of catalytic amounts of Ag2CO3 and a stoichiometric amount of K2S2O8. Unfortunately, 3aa was obtained only in 14% yield (Table 1, entry 18). Further improvement was achieved by increasing the amount of 1,10-phenanthroline and 3aa could be isolated in 81% yield (Table 1, entries 19, 20). Finally, it was found that decreasing the reaction temperature to 150 oC resulted in 3aa with a slightly reduced yield (Table 1, entry 21). Table 2. Substrate Scope of the Aromatic Carboxylic Acidsa

a

Reaction conditions: 1 (0.3 mmol), 2a (2.0 equiv), Ag2CO3 (1.5 equiv), 1,10-phenanthroline (0.6

equiv), PhCF3 (3 mL), 160 °C, air, 18 h. Isolated yield. bReaction time was 36 h. With the optimized conditions in hand, we next sought to explore the substrate scope of the decarboxylative sulfonylation reaction with respect to aryl carboxylic acids (Table 2). It was found that 2-nitrobenzoic acids substituted with electron-withdrawing (chloro, bromo, and trifluoromethyl) or electron-donating (methyl and methoxy) groups on the aryl rings all reacted


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satisfactorily with sodium 4-methylbenzenesulfinate (2a) to give the corresponding products in moderate to good yields (3aa-3la). It should be mentioned that sterically hindered substrate 1h could be subjected to the decarboxylative sulfonylation reaction, delivering the desired product 3ha in 52% yield. We were delighted to find that the scope of carboxylic acids was not limited to 2-nitrobenzoic acid derivatives in this protocol. The reactions of 2-(methylsulfonyl)benzoic acid and 2-fluorobenzoic acid proceeded smoothly to produce the corresponding decarboxylative sulfonylation products 3ma and 3na, albeit with slightly lower yields. Moreover, 2-chloro-5-nitrobenzoic

acid,

3-methylbenzofuran-2-carboxylic

acid,

and

3-chlorobenzo[b]thiophene-2-carboxylic acid were also viable substrates, affording 3oa, 3pa, and 3qa in 43%, 41%, and 39% yield, respectively. It is worth noting that the presence of halogen atoms (chloro and bromo) in products 3 offers the opportunity for further synthetic transformations via cross-coupling reactions (3ca-3ea, 3la and 3oa). We were disappointed to find that parent benzoic acid, 3-nitrobenzoic acid, 4-nitrobenzoic acid, 2-methylbenzoic acid, as well as the 2-methoxybenzoic acid could not afford the corresponding decarboxylative sulfonylation products under standard conditions. The reason why 2-nitrobenzoic acid derivatives provided better results than other aryl carboxylic acid derivatives may be due to the fact that the ortho-nitro groups can stabilize Ar-Ag species formed in situ after decarboxylation through Ag-O coordination.20 Table 3. Substrate Scope of the Sodium Sulfinatesa



a

Reaction conditions: 1a (0.3 mmol), 2 (2.0 equiv), Ag2CO3 (1.5 equiv), 1,10-phenanthroline (0.6

equiv), PhCF3 (3 mL), 160 °C, air, 18 h. Isolated yield. Next, the scope of the sodium sulfinates was investigated. As shown in Table 3, a variety of sodium sulfinates were compatible with this transformation. Functional groups such as halogens (3ad, 3ae, 3ag-3ai), trifluoromethyl (3aj) and nitro (3af and 3ak) attached to the aryl ring were all well tolerated, giving the desired products in moderate to good yields. From the table, we can see product 3ac derived from an ortho-substituted sodium sulfinate was obtained with lower yield, which may be due to steric hindrance. Furthermore, sodium naphthalene-2-sulfinate could also participate in the reaction to afford the corresponding product 3an in 78% yield. It should be noted that sodium cyclopropanesulfinate, an aliphatic sodium sulfinate, also proved to be a good substrate, delivering the desired product 3ao in 67% yield. Unfortunately, CF3SO2Na and CH3SO2Na were found to be incompatible for the system, perhaps due to the instability of the corresponding alkyl sulfone radical intermediate. Scheme 1. Derivatization of the Obtained Product

Subsequently, we performed several experiments to highlight the synthetic utility of the


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decarboxylative sulfonylation product (Scheme 1). 2-Nitro-4-(phenylethynyl)-1-tosylbenzene (4a) could be produced in 94% yield via Sonogashira cross-coupling (Scheme 1a). Moreover, Suzuki coupling of 3ea with phenylboronic acid could afford 3-nitro-4-tosyl-1,1'-biphenyl (4b) in 89% yield (Scheme 1b). Scheme 2. Mechanism Experiments

Preliminary mechanism experiments were conducted to gain insights into the reaction (Scheme 2). When radical scavenger TEMPO or BHT was added to the reaction mixture under the standard conditions, the formation of 3aa was totally suppressed (Scheme 2a). This result reveals that a radical pathway is likely to be involved in the reaction. It should be noted that in both cases nitrobenzene could be detected by GC-MS analysis (please see Supporting Information), however, we did not detect the TEMPO-bound adduct in the presence of radical scavenger TEMPO. Therefore, we attempted to trap the radical intermediate with 1,1-diphenylethylene. Much to our satisfaction, vinyl sulfone 5 could be isolated in 18% yield, suggesting the involvement of sulfonyl radicals (Scheme 2b). Scheme 3. Possible Reaction Mechanism

On the basis of the above investigations and previous literature reports,21 a plausible reaction mechanism is proposed in Scheme 3. Initially, the reaction of aromatic carboxylic acid 1 with the Ag2CO3 gives silver carboxylate A, which in turn affords the aryl-Ag(I) species B by the loss of a molecule of carbon dioxide. Meanwhile, sodium sulfinate 2 is oxidized by Ag(I) to generate an oxygen-centered radical C, which could be easily resonated to sulfonyl radical D. Subsequently, the sulfonyl radical D reacts with aryl-Ag(I) species B to provide the Ag(II) intermediate E. Finally, reductive elimination of E gives the decarboxylative sulfonylation product 3. Since it is



well known that Ag-catalyzed proto-decarboxylation of 2-nitrobenzoic acid can proceed around 120 oC and our reactions are ran at significantly higher temperature. We suspect that higher temperature could be beneficial for the formation of Ag (II) intermediate E via the reaction of sulfonyl radical D with aryl-Ag (I) species B. In conclusion, we have developed a novel and efficient strategy for the synthesis of sulfones via silver-promoted decarboxylative sulfonylation reaction of aromatic carboxylic acids with sodium sulfinates. This reaction proceeds readily under air atmosphere and is simple to operate. This transformation uses readily available aromatic carboxylic acids and sodium sulfinates as starting materials, and a variety of sulfones could be efficiently obtained in moderate to good yields. Preliminary mechanism investigations revealed that the reaction probably proceeds through a radical pathway. Further studies on extending the substrate scope are underway, and the results will be forthcoming. EXPERIMENTAL SECTION General. Unless otherwise noted, all reagents were obtained from commercial suppliers and used without further purification. The sodium sulfinates were prepared according the previous reports.22 Products were purified by column chromatography on 200-300 mesh silica gel, SiO2. 1H and 13C NMR spectra were measured on a 400 MHz NMR spectrometer using CDCl3 or DMSO-d6 as the solvent. The chemical shifts are given in δ relative to TMS, and the coupling constants are given in Hertz. The peak patterns are indicated as follows: s, singlet; d, doublet; t, triplet; q, quartet; m, multiplet; qui, quintet; sxt, sextet. The high-resolution mass spectra (HRMS) analyses were conducted using a TOF MS instrument with an ESI source. Melting points were measured by a melting point instrument and were uncorrected. General Procedure for Silver-Promoted Decarboxylative Sulfonylation Reaction of Aromatic Carboxylic Acids with Sodium Sulfinates. Benzoic acid 1 (0.3 mmol), Ag2CO3 (124.1 mg, 0.45 mmol), 1,10-phenanthroline (32.4 mg, 0.18 mmol), sodium sulfinate 2 (0.6 mmol) and PhCF3 (3.0 mL) were added to a 25 mL Schlenk flask equipped with a high-vacuum PTFE valve-to-glass seal. Then the flask was sealed under air and stirred at 160 oC (oil bath) for 18 h. The cooled reaction mixture was diluted with DCM (10 mL) and filtered through a short pad of silica gel, which then was washed with more DCM (3 × 10 mL). The solvent was removed in vacuum and the product was isolated through column chromatography to afford the desired product 3.


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1-Nitro-2-tosylbenzene (3aa). Purification by column chromatography on silica gel (petroleum ether/ethyl acetate = 8/1, v/v) afforded 3aa as a white solid (67.3 mg, 81% yield); mp 151-153 oC; 1

H NMR (400 MHz, CDCl3): δ 8.32 (d, J = 7.2 Hz, 1H), 7.86 (d, J = 7.6 Hz, 2H), 7.78-7.68 (m,

3H), 7.35 (d, J = 7.6 Hz, 2H), 2.43 (s, 3H);

13

C{1H} NMR (100 MHz, CDCl3): δ 148.4, 145.0,

137.3, 134.8, 134.4, 132.4, 131.4, 129.7, 128.3, 124.6, 21.6; HRMS (ESI, m/z) calcd for C13H12NO4S [M + H]+ 278.0482, found 278.0490. Larger-Scale Synthesis of 3aa. 2-Nitrobenzoic acid 1a (334.2 mg, 2.0 mmol), Ag2CO3 (827.2 mg, 3.0 mmol), 1,10-phenanthroline (216.0 mg, 1.2 mmol), sodium 4-methylbenzenesulfinate 2a (712.7 mg, 4.0 mmol) and PhCF3 (20 mL) were added to a 50 mL Schlenk flask equipped with a high-vacuum PTFE valve-to-glass seal. Then the flask was sealed under air and stirred at 160 oC (oil bath) for 18 h. The cooled reaction mixture was diluted with DCM (20 mL) and filtered through a short pad of silica gel, which then was washed with more DCM (3 × 10 mL). The solvent was removed in vacuum and the product was isolated through column chromatography on silica gel (petroleum ether/ethyl acetate = 8/1, v/v) to afford 3aa (388.2 mg, 70% yield). 1-Methyl-2-nitro-3-tosylbenzene (3ba). Purification by column chromatography on silica gel (petroleum ether/ethyl acetate = 8/1, v/v) afforded 3ba as a light yellow solid (50.6 mg, 58% yield); mp 129-131 oC; 1H NMR (400 MHz, CDCl3): δ 8.02-8.01 (m, 1H), 7.82 (d, J = 7.6 Hz, 2H), 7.54-7.53 (m, 2H), 7.33 (d, J = 7.6 Hz, 2H), 2.41 (s, 3H), 2.30 (s, 3H); 13C{1H} NMR (100 MHz, CDCl3): δ 148.2, 145.1, 137.4, 136.6, 133.3, 131.4, 130.4, 129.8, 128.3, 128.2, 21.6, 17.0; HRMS (ESI, m/z) calcd for C14H13NO4SNa [M + Na]+ 314.0457, found 314.0465. 1-Chloro-2-nitro-3-tosylbenzene (3ca). Purification by column chromatography on silica gel (petroleum ether/ethyl acetate = 8/1, v/v) afforded 3ca as a white solid (57.8 mg, 62% yield); mp 150-152 oC; 1H NMR (400 MHz, CDCl3): δ 8.07 (d, J = 8.0 Hz, 1H), 7.82 (d, J = 8.0 Hz, 2H), 7.72 (d, J = 8.0 Hz, 1H), 7.60 (t, J = 8.0 Hz, 1H), 7.35 (d, J = 7.6 Hz, 2H), 2.43 (s, 3H); 13C{1H} NMR (100 MHz, CDCl3): δ 146.4, 145.7, 136.7, 135.5, 135.2, 131.3, 130.1, 129.0, 128.4, 127.1, 21.7; HRMS (ESI, m/z) calcd for C13H10ClNO4SNa [M + Na]+ 333.9911, found 333.9902. 4-Chloro-2-nitro-1-tosylbenzene (3da). Purification by column chromatography on silica gel (petroleum ether/ethyl acetate = 8/1, v/v) afforded 3da as a white solid (63.4 mg, 68% yield); mp 106-108 oC; 1H NMR (400 MHz, CDCl3): δ 8.26 (d, J = 8.4 Hz, 1H), 7.84 (d, J = 7.6 Hz, 2H), 7.72 (d, J = 8.4 Hz, 1H), 7.68 (s, 1H), 7.35 (d, J = 7.6 Hz, 2H), 2.43 (s, 3H); 13C{1H} NMR (100



MHz, CDCl3): δ 148.7, 145.3, 140.7, 137.0, 133.3, 132.6, 132.4, 129.8, 128.4, 124.8, 21.6; HRMS (ESI, m/z) calcd for C13H10ClNO4SNa [M + Na]+ 333.9911, found 333.9915. 4-Bromo-2-nitro-1-tosylbenzene (3ea). Purification by column chromatography on silica gel (petroleum ether/ethyl acetate = 10/1, v/v) afforded 3ea as a white solid (77.7 mg, 73% yield); mp 114-116 oC; 1H NMR (400 MHz, CDCl3): δ 8.18 (d, J = 8.4 Hz, 1H), 7.88 (d, J = 8.4 Hz, 1H), 7.85-7.83(m, 3H), 7.36 (d, J = 7.6 Hz, 2H), 2.44 (s, 3H);

13

C{1H} NMR (100 MHz, CDCl3): δ

148.5, 145.3, 136.9, 135.5, 133.8, 132.6, 129.8, 128.7, 128.4, 127.6, 21.7; HRMS (ESI, m/z) calcd for C13H10BrNO4SNa [M + Na]+ 377.9406, found 377.9409. 2-Nitro-1-tosyl-4-(trifluoromethyl)benzene (3fa). Purification by column chromatography on silica gel (petroleum ether/ethyl acetate = 20/1, v/v) afforded 3fa as a white solid (68.3 mg, 66% yield); mp 133-135 oC; 1H NMR (400 MHz, CDCl3): δ 8.48 (d, J = 8.0 Hz, 1H), 8.01 (d, J = 8.4 Hz, 1H), 7.95 (s, 1H), 7.87 (d, J = 8.0 Hz, 2H), 7.38 (d, J = 7.6 Hz, 2H), 2.45 (s, 3H); 13C{1H} NMR (100 MHz, CDCl3): δ 148.5, 145.8, 138.3, 136.3, 136.2 (q, J = 34.9 Hz), 132.4, 130.0, 129.2 (q, J = 3.5 Hz), 128.7, 122.0 (q, J = 3.5 Hz), 121.9 (q, J = 272.1 Hz), 21.7; 19F NMR (376 MHz, CDCl3): δ -63.3; HRMS (ESI, m/z) calcd for C14H10F3NO4SNa [M + Na]+ 368.0175, found 368.0178. 4-Methoxy-2-nitro-1-tosylbenzene (3ga). Purification by column chromatography on silica gel (petroleum ether/ethyl acetate = 4/1, v/v) afforded 3ga as a white solid (66.3 mg, 72% yield); mp 118-120 oC; 1H NMR (400 MHz, CDCl3): δ 8.24 (d, J = 8.8 Hz, 1H), 7.83 (d, J = 7.6 Hz, 2H), 7.33 (d, J = 8.0 Hz, 2H), 7.19-7.17 (m, 2H), 3.91 (s, 3H), 2.42 (s, 3H); 13C{1H} NMR (100 MHz, CDCl3): δ 163.7, 149.8, 144.5, 138.1, 133.3, 129.6, 128.0, 126.2, 116.9, 110.6, 56.4, 21.6; HRMS (ESI, m/z) calcd for C14H14NO5S [M + H]+ 308.0587, found 308.0583. 1-Methyl-3-nitro-2-tosylbenzene (3ha). Purification by column chromatography on silica gel (petroleum ether/ethyl acetate = 8/1, v/v) afforded 3ha as a white solid (45.4 mg, 52% yield); mp 132-134 oC; 1H NMR (400 MHz, CDCl3): δ 7.96 (d, J = 7.6 Hz, 2H), 7.56 (t, J = 7.6 Hz, 1H), 7.40-7.34 (m, 4H), 2.58 (s, 3H), 2.43 (s, 3H); 13C{1H} NMR (100 MHz, CDCl3): δ 151.1, 145.2, 141.5, 137.2, 135.1, 133.9, 131.1, 129.8, 127.9, 121.9, 21.6, 21.5; HRMS (ESI, m/z) calcd for C14H14NO4S [M + H]+ 292.0638, found 292.0640. 4-Methoxy-1-nitro-2-tosylbenzene (3ia). Purification by column chromatography on silica gel (petroleum ether/ethyl acetate = 4/1, v/v) afforded 3ia as a white solid (65.4 mg, 71% yield); mp 151-153 oC; 1H NMR (400 MHz, CDCl3): δ 7.90 (s, 1H), 7.86-7.83 (m, 3H), 7.34 (d, J = 8.0 Hz,


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2H), 7.13 (d, J = 8.8 Hz, 1H), 3.97 (s, 3H), 2.42 (s, 3H);

13


162.6, 144.7, 141.0, 137.4, 129.5, 128.2, 127.7, 117.9, 117.2, 56.5, 21.6; HRMS (ESI, m/z) calcd for C14H14NO5S [M + H]+ 308.0587, found 308.0590. 1,2-Dimethoxy-4-nitro-5-tosylbenzene (3ja). Purification by column chromatography on silica gel (petroleum ether/ethyl acetate = 4/1, v/v) afforded 3ja as a white solid (63.7 mg, 63% yield); mp 167-169 oC; 1H NMR (400 MHz, CDCl3): δ 7.83-7.81 (m, 3H), 7.35-7.31 (m, 3H), 4.07 (s, 3H), 3.96 (s, 3H), 2.42 (s, 3H); 13C{1H} NMR (100 MHz, CDCl3): δ 152.3, 151.6, 144.4, 141.8, 138.1, 129.5, 128.1, 127.9, 112.7, 108.1, 56.9, 56.8, 21.6; HRMS (ESI, m/z) calcd for C15H16NO6S [M + H]+ 338.0693, found 338.0691. 4-Methyl-1-nitro-2-tosylbenzene (3ka). Purification by column chromatography on silica gel (petroleum ether/ethyl acetate = 10/1, v/v) afforded 3ka as a white solid (53.3 mg, 61% yield); mp 168-170 oC; 1H NMR (400 MHz, CDCl3): δ 8.15 (s, 1H), 7.86 (d, J = 8.0 Hz, 2H), 7.65 (d, J = 8.0 Hz, 1H), 7.50 (d, J = 8.0 Hz, 1H), 7.34 (d, J = 7.6 Hz, 2H), 2.54 (s, 3H), 2.43 (s, 3H); 13C{1H} NMR (100 MHz, CDCl3): δ 146.2, 144.8, 144.0, 137.6, 134.8, 134.6, 131.8, 129.6, 128.3, 124.9, 21.7, 21.5; HRMS (ESI, m/z) calcd for C14H14NO4S [M + H]+ 292.0638, found 292.0632. 4-Chloro-1-nitro-2-tosylbenzene (3la). Purification by column chromatography on silica gel (petroleum ether/ethyl acetate = 8/1, v/v) afforded 3la as a white solid (60.6 mg, 65% yield); mp 180-182 oC; 1H NMR (400 MHz, CDCl3): δ 8.32 (s, 1H), 7.86 (d, J = 7.6 Hz, 2H), 7.71-7.66 (m, 2H), 7.37 (d, J = 7.6 Hz, 2H), 2.44 (s, 3H);

13

C{1H} NMR (100 MHz, CDCl3): δ 146.5, 145.5,

139.0, 136.8, 136.7, 134.1, 131.4, 129.8, 128.6, 126.1, 21.7; HRMS (ESI, m/z) calcd for C13H10ClNO4SNa [M + Na]+ 333.9911, found 333.9910. 1-(Methylsulfonyl)-2-tosylbenzene (3ma). Purification by column chromatography on silica gel (petroleum ether/ethyl acetate = 8/1, v/v) afforded 3ma as a white solid (35.3 mg, 38% yield); mp 151-153 oC; 1H NMR (400 MHz, CDCl3): δ 8.52 (d, J = 7.6 Hz, 1H), 8.32 (d, J = 7.6 Hz, 1H), 7.88-7.79 (m, 4H), 7.29 (d, J = 7.6 Hz, 2H), 3.51 (s, 3H), 2.39 (s, 3H); 13C{1H} NMR (100 MHz, CDCl3): δ 144.5, 140.8, 139.8, 138.0, 134.2, 134.0, 133.1, 132.4, 129.4, 128.3, 45.6, 21.6; HRMS (ESI, m/z) calcd for C14H15O4S2 [M + H]+ 311.0406, found 311.0399. 1-Fluoro-2-tosylbenzene(3na). Purification by column chromatography on silica gel (petroleum ether/ethyl acetate = 8/1, v/v) afforded 3na as a white solid (27.0 mg, 36% yield); mp 110-112 oC; 1

H NMR (400 MHz, CDCl3): δ 8.08 (t, J = 7.2 Hz, 1H), 7.89 (d, J = 7.6 Hz, 2H), 7.58-7.53 (m,



Page 12 of 23

1H), 7.32-7.28 (m, 3H), 7.08 (t, J = 9.2 Hz, 1H), 2.41 (s, 3H); 13C{1H} NMR (100 MHz, CDCl3): δ 159.1 (d, J = 255.5 Hz), 144.7, 137.9, 135.7 (d, J = 8.4 Hz), 129.7, 129.6, 128.1, 124.5 (d, J = 3.8 Hz), 117.2 (d, J = 21.1 Hz), 21.6; 19F NMR(376 MHz, CDCl3): δ −107.8; HRMS (ESI, m/z) calcd for C13H12FO2S [M + H]+ 251.0537, found 251.0541. 1-Chloro-4-nitro-2-tosylbenzene(3oa). Purification by column chromatography on silica gel (petroleum ether/ethyl acetate = 8/1, v/v) afforded 3oa as a white solid (40.1 mg, 43% yield); mp 188-190 oC; 1H NMR (400 MHz, CDCl3): δ 9.17 (d, J = 2.4 Hz, 1H), 8.34 (dd, J = 8.8, 2.4 Hz, 1H), 7.87 (d, J = 8.4 Hz, 2H), 7.62 (d, J = 8.8 Hz, 1H), 7.35 (d, J = 8.0 Hz, 2H), 2.44 (s, 3H); 13

C{1H} NMR (100 MHz, CDCl3): δ 146.4, 145.6, 140.7, 139.5, 135.6, 133.3, 129.8, 129.0, 128.5,

126.1, 21.7; HRMS (ESI, m/z) calcd for C13H11ClNO4S [M + H]+ 312.0092, found 312.0090. 3-Methyl-2-tosylbenzofuran (3pa). Purification by column chromatography on silica gel (petroleum ether/ethyl acetate = 50/1, v/v) afforded 3pa as a white solid (35.2 mg, 41% yield); mp 112-114 oC; 1H NMR (400 MHz, CDCl3): δ 7.95 (d, J = 7.6 Hz, 2H), 7.59 (d, J = 7.6 Hz, 1H), 7.47-7.40 (m, 2H), 7.34-7.28 (m, 3H), 2.64 (s, 3H), 2.41 (s, 3H);

13

C{1H} NMR (100 MHz,

CDCl3): δ 154.6, 145.7, 144.9, 137.6, 129.9, 128.2, 128.0, 127.7, 123.6, 123.5, 121.3, 112.2, 21.6, 8.6; HRMS (ESI, m/z) calcd for C16H15O3S [M + H]+ 287.0736, found 287.0758. 3-Chloro-2-tosylbenzo[b]thiophene (3qa). Purification by column chromatography on silica gel (petroleum ether/ethyl acetate = 50/1, v/v) afforded 3qa as a white solid (37.7 mg, 39% yield); mp 169-171 oC; 1H NMR (400 MHz, CDCl3): δ 8.00 (d, J = 8.4 Hz, 2H), 7.86-7.81 (m, 2H), 7.54-7.45 (m, 2H), 7.34 (d, J = 8.0 Hz, 2H), 2.41 (s, 3H); 13C{1H} NMR (100 MHz, CDCl3): δ 145.1, 138.5, 137.3, 136.6, 136.5, 129.8, 128.4, 128.2, 125.9, 124.8, 123.6, 122.8, 21.6; LRMS (EI, 70 ev) m/z (%):322 (M+, 56), 281 (33), 207 (73), 139 (100). 1-Nitro-2-(phenylsulfonyl)benzene (3ab). Purification by column chromatography on silica gel (petroleum ether/ethyl acetate = 8/1, v/v) afforded 3ab as a white solid (65.5 mg, 83% yield); mp 145-147 oC; 1H NMR (400 MHz, CDCl3): δ 8.35 (d, J = 7.2 Hz, 1H), 7.97 (d, J = 7.6 Hz, 2H), 7.80-7.71 (m, 3H), 7.63 (t, J = 7.6 Hz, 1H), 7.55 (t, J = 7.6 Hz, 2H); 13C{1H} NMR (100 MHz, CDCl3): δ 148.4, 140.3, 134.6, 134.4, 133.8, 132.5, 131.5, 129.1, 128.2, 124.7; HRMS (ESI, m/z) calcd for C12H9NO4SNa [M + Na]+ 286.0144, found 286.0148. 1-Methyl-2-((2-nitrophenyl)sulfonyl)benzene (3ac). Purification by column chromatography on silica gel (petroleum ether/ethyl acetate = 8/1, v/v) afforded 3ac as a white solid (44.0 mg, 53%


Page 13 of 23 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


yield); mp 139-141 oC; 1H NMR (400 MHz, CDCl3): δ 8.35 (d, J = 7.2 Hz, 1H), 8.06 (d, J = 8.0 Hz, 1H), 7.83-7.78 (m, 3H), 7.53 (t, J = 7.2 Hz, 1H), 7.42 (t, J = 7.6 Hz, 1H), 7.27 (d, J = 7.6 Hz, 1H), 2.47 (s, 3H); 13C{1H} NMR (100 MHz, CDCl3): δ 148.4, 138.5, 137.2, 134.6, 134.4, 133.9, 132.5, 132.4, 131.8, 130.0, 126.3, 125.1, 20.2; HRMS (ESI, m/z) calcd for C13H12NO4S [M + H]+ 278.0482, found 278.0476. 1-((3-Chlorophenyl)sulfonyl)-2-nitrobenzene (3ad). Purification by column chromatography on silica gel (petroleum ether/ethyl acetate = 8/1, v/v) afforded 3ad as a white solid (57.9 mg, 65% yield); mp 130-132 oC; 1H NMR (400 MHz, CDCl3): δ 8.38 (d, J = 6.4 Hz, 1H), 7.92 (s, 1H), 7.88 (d, J = 7.6 Hz, 1H), 7.83-7.79 (m, 3H), 7.60 (d, J = 7.6 Hz, 1H), 7.51 (t, J = 7.6 Hz, 1H); 13C{1H} NMR (100 MHz, CDCl3): δ 148.5, 142.2, 135.3, 135.0, 133.9, 132.8, 131.8, 130.4, 128.1, 126.3, 125.0; HRMS (ESI, m/z) calcd for C12H8ClNO4SNa [M + Na]+ 319.9755, found 319.9758. 1-((3-Bromophenyl)sulfonyl)-2-nitrobenzene (3ae). Purification by column chromatography on silica gel (petroleum ether/ethyl acetate = 8/1, v/v) afforded 3ae as a white solid (67.5 mg, 66% yield); mp 130-132 oC; 1H NMR (400 MHz, CDCl3): δ 8.36 (d, J = 6.8 Hz, 1H), 8.06 (s, 1H), 7.92 (d, J = 8.0 Hz, 1H), 7.85-7.79 (m, 3H), 7.75 (d, J = 8.0 Hz, 1H), 7.44 (t, J = 8.0 Hz, 1H); 13C{1H} NMR (100 MHz, CDCl3): δ 148.5, 142.3, 136.8, 135.0, 133.9, 132.8, 131.8, 130.8, 130.6, 126.8, 125.0, 122.9; HRMS (ESI, m/z) calcd for C12H8BrNO4SNa [M + Na]+ 363.9250, found 363.9247. 1-Nitro-2-((3-nitrophenyl)sulfonyl)benzene (3af). Purification by column chromatography on silica gel (petroleum ether/ethyl acetate = 4/1, v/v) afforded 3af as a light yellow solid (53.6 mg, 58% yield); mp 172-174 oC; 1H NMR(400 MHz, DMSO-d6): δ 8.64 (s, 1H), 8.59 (d, J = 8.0 Hz, 1H), 8.52 (d, J = 6.4 Hz, 1H), 8.42 (d, J = 7.6 Hz, 1H), 8.10 (d, J = 6.8 Hz, 1H), 8.04-7.98 (m, 3H); 13

C{1H} NMR (100 MHz, DMSO-d6): δ 148.0, 147.9, 141.5, 136.7, 133.8, 133.7, 132.2, 131.8,

131.4, 129.0, 125.4, 122.5; HRMS (ESI, m/z) calcd for C12H8N2O6SNa [M + Na]+ 330.9995, found 330.9991. 1-((4-Fluorophenyl)sulfonyl)-2-nitrobenzene (3ag). Purification by column chromatography on silica gel (petroleum ether/ethyl acetate = 8/1, v/v) afforded 3ag as a white solid (59.9 mg, 71% yield); mp 139-141 oC; 1H NMR (400 MHz, CDCl3): δ 8.35 (d, J = 7.2 Hz, 1H), 8.02-7.99 (m, 2H), 7.82-7.74 (m, 3H), 7.24 (t, J = 8.0 Hz, 2H);

13

C{1H} NMR (100 MHz, CDCl3): δ 165.8 (d,

J=255.6 Hz), 148.5, 136.4 (d, J=3.1 Hz), 134.7, 134.5, 132.6, 131.5, 131.3 (d, J=9.7 Hz), 124.8, 116.5 (d, J=22.7 Hz);

19

F NMR(376 MHz, CDCl3): δ −102.7; HRMS (ESI, m/z) calcd for



Page 14 of 23

C12H8FNO4SNa [M + Na]+ 304.0050, found 304.0051. 1-((4-Chlorophenyl)sulfonyl)-2-nitrobenzene (3ah). Purification by column chromatography on silica gel (petroleum ether/ethyl acetate = 8/1, v/v) afforded 3ah as a light yellow solid (68.6 mg, 77% yield); mp 135-137 oC; 1H NMR (400 MHz, CDCl3): δ 8.35 (d, J = 6.8 Hz, 1H), 7.91 (d, J = 8.0 Hz, 2H), 7.82-7.74 (m, 3H), 7.53 (d, J = 7.6 Hz, 2H);

13


148.4, 140.6, 138.8, 134.9, 134.2, 132.7, 131.6, 129.7, 129.4, 124.9; HRMS (ESI, m/z) calcd for C12H8ClNO4SNa [M + Na]+ 319.9755, found 319.9756. 1-((4-Bromophenyl)sulfonyl)-2-nitrobenzene (3ai). Purification by column chromatography on silica gel (petroleum ether/ethyl acetate = 10/1, v/v) afforded 3ai as a white solid (65.5 mg, 64% yield); mp 135-137 oC; 1H NMR (400 MHz, CDCl3): δ 8.36 (d, J = 6.8 Hz, 1H), 7.84-7.77 (m, 5H), 7.70 (d, J = 7.6 Hz, 2H); 13C{1H} NMR (100 MHz, CDCl3): δ 148.5, 139.4, 134.8, 134.2, 132.7, 132.4, 131.6, 129.8, 129.2, 124.9; HRMS (ESI, m/z) calcd for C12H8BrNO4SNa [M + Na]+ 363.9250, found 363.9252. 1-Nitro-2-((4-(trifluoromethyl)phenyl)sulfonyl)benzene

(3aj).

Purification

by

column

chromatography on silica gel (petroleum ether/ethyl acetate = 8/1, v/v) afforded 3aj as a white solid (71.5 mg, 72% yield); mp 121-123 oC; 1H NMR (400 MHz, CDCl3): δ 8.42 (d, J = 7.2 Hz, 1H), 8.10 (d, J = 8.0 Hz, 2H), 7.84-7.82 (m, 5H);

13

C{1H} NMR (100 MHz, CDCl3): δ 148.6,

144.1, 135.3 (q, J = 33.0 Hz), 135.2, 133.7, 132.9, 131.9, 128.7, 126.2 (q, J = 3.6 Hz), 125.1, 123.0 (q, J = 271.4 Hz); 19F NMR (376 MHz, CDCl3): δ -63.2; HRMS (ESI, m/z) calcd for C13H8F3NO4SNa [M + Na]+ 354.0018, found 354.0019. 1-Nitro-2-((4-nitrophenyl)sulfonyl)benzene (3ak). Purification by column chromatography on silica gel (petroleum ether/ethyl acetate = 4/1, v/v) afforded 3ak as a light yellow solid (47.1 mg, 51% yield); mp 202-204 oC; 1H NMR (400 MHz, DMSO-d6): δ 8.50-8.46 (m, 3H), 8.22 (d, J = 8.0 Hz, 2H), 8.11 (d, J = 6.8 Hz, 1H), 8.05-8.03 (m, 2H);

13

C{1H} NMR (100 MHz, DMSO-d6): δ

150.6, 147.9, 145.3, 136.8, 133.8, 132.1, 131.2, 129.2, 125.5, 124.9; HRMS (ESI, m/z) calcd for C12H8N2O6SNa [M + Na]+ 330.9995, found 330.9987. 1-((4-Methoxyphenyl)sulfonyl)-2-nitrobenzene (3al). Purification by column chromatography on silica gel (petroleum ether/ethyl acetate = 4/1, v/v) afforded 3al as a white solid (46.6 mg, 53% yield); mp 151-153 oC; 1H NMR (400 MHz, CDCl3): δ 8.30 (d, J = 7.2 Hz, 1H), 7.92 (d, J = 7.6 Hz, 2H), 7.77-7.67 (m, 3H), 7.01 (d, J = 7.6 Hz, 2H), 3.87 (s, 3H);


13

C{1H} NMR (100 MHz,

Page 15 of 23 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


CDCl3): δ 163.9, 148.3, 135.2, 134.2, 132.3, 131.6, 131.2, 130.8, 124.5, 114.3, 55.7; HRMS (ESI, m/z) calcd for C13H12NO5S [M + H]+ 294.0431, found 294.0427. 1-((4-(Tert-butyl)phenyl)sulfonyl)-2-nitrobenzene (3am). Purification by column chromatography on silica gel (petroleum ether/ethyl acetate = 8/1, v/v) afforded 3am as a white solid (54.6 mg, 57% yield); mp 126-128 oC; 1H NMR (400 MHz, CDCl3): δ 8.34 (d, J = 7.2 Hz, 1H), 7.91 (d, J = 7.6 Hz, 2H), 7.79-7.70 (m, 3H), 7.56 (d, J = 7.6 Hz, 2H), 1.33 (s, 9H); 13C{1H} NMR (100 MHz, CDCl3): δ 157.9, 148.4, 137.2, 134.9, 134.4, 132.4, 131.5, 128.2, 126.1, 124.6, 35.3, 31.0; HRMS (ESI, m/z) calcd for C16H18NO4S [M + H]+ 320.0951, found 320.0949. 2-((2-Nitrophenyl)sulfonyl)naphthalene (3an). Purification by column chromatography on silica gel (petroleum ether/ethyl acetate = 8/1, v/v) afforded 3an as a light yellow solid (73.3 mg, 78% yield); mp 143-145 oC; 1H NMR (400 MHz, CDCl3): δ 8.60 (s, 1H), 8.41 (d, J = 7.6 Hz, 1H), 8.01 (d, J = 8.0 Hz, 1H), 7.97 (d, J = 8.8 Hz, 1H), 7.89 (d, J = 8.4 Hz, 2H), 7.80-7.69 (m, 3H), 7.67-7.59 (m, 2H); 13C{1H} NMR (100 MHz, CDCl3): δ 148.4, 137.1, 135.2, 134.6, 134.5, 132.5, 131.9, 131.6, 130.3, 129.6, 129.5, 129.3, 127.9, 127.7, 124.7, 122.6; HRMS (ESI, m/z) calcd for C16H11NO4SNa [M + Na]+ 336.0301, found 336.0304. 1-(Cyclopropylsulfonyl)-2-nitrobenzene (3ao). Purification by column chromatography on silica gel (petroleum ether/ethyl acetate = 8/1, v/v) afforded 3ao as an orange solid (45.6 mg, 67% yield); mp 95-97 oC; 1H NMR (400 MHz, CDCl3): δ 8.01 (d, J = 7.2 Hz, 1H), 7.84 (d, J = 7.2 Hz, 1H), 7.81-7.74 (m, 2H), 3.28-3.23 (m, 1H), 1.41-1.40 (m, 2H), 1.15-1.13 (m, 2H); 13C{1H} NMR (100 MHz, CDCl3): δ 149.1, 134.3, 134.0, 132.6, 131.2, 124.9, 33.0, 6.8; HRMS (ESI, m/z) calcd for C9H9NO4SNa [M + Na]+ 250.0144, found 250.0144. 2-Nitro-4-(phenylethynyl)-1-tosylbenzene (4a). 4-Bromo-2-nitro-1-tosylbenzene 3ea (71.2 mg, 0.2 mmol), copper(I) iodide (1.5 mg, 0.008 mmol), and bis(triphenylphosphine) palladium(II) dichloride (5.6 mg, 0.008 mmol) were added to a 25 mL Schlenk flask equipped with a high-vacuum PTFE valve-to-glass seal. The tube was evacuated and backfilled with N2 three times after which triethylamine (40.5 mg, 0.4 mmol) and THF (1 mL) were added via syringe. After 5 min at room temperature, the phenylacetylene (28.6 mg, 0.28 mmol) was added. The resulting mixture was stirred at 80 °C (oil bath) for 12 h. It was then cooled to room temperature, and the reaction mixture was quenched with H2O (20 mL), extracted with DCM (20 mL × 3), washed with brine. The combined organic layers were dried over anhydrous Na2SO4, filtered, and concentrated.



Page 16 of 23

Purification by column chromatography on silica gel (petroleum ether/ethyl acetate = 8/1, v/v) afforded 4a as a light yellow solid (70.9 mg, 94% yield); mp 176-178 oC; 1H NMR (400 MHz, CDCl3): δ 8.28 (d, J = 8.0 Hz, 1H), 7.87 (d, J = 7.6 Hz, 2H), 7.83-7.80 (m, 2H), 7.54 (d, J = 7.2 Hz, 2H), 7.41-7.35 (m, 5H), 2.44 (s, 3H); 13C{1H} NMR (100 MHz, CDCl3): δ 148.4, 145.1, 137.3, 134.6, 133.4, 131.9, 131.4, 130.3, 129.8, 129.7, 128.6, 128.4, 127.0, 121.3, 96.1, 85.7, 21.7; HRMS (ESI, m/z) calcd for C21H16NO4S [M + H]+ 378.0795, found 378.0790. 3-Nitro-4-tosyl-1,1'-biphenyl (4b). 4-Bromo-2-nitro-1-tosylbenzene 3ea (71.2 mg, 0.2 mmol), phenylboronic acid (29.3 mg, 0.24 mmol), K2CO3 (55.3 mg, 0.4 mmol), and Pd(PPh3)4 (11.6 mg, 0.01 mmol) were added to a 25 mL Schlenk flask equipped with a high-vacuum PTFE valve-to-glass seal. The tube was evacuated and backfilled with N2 three times after which toluene (1 mL) was added via syringe. The resulting mixture was stirred at 110 °C (oil bath) for 12 h. It was then cooled to room temperature, and the reaction mixture was quenched with H2O (20 mL), extracted with DCM (20 mL × 3), washed with brine. The combined organic layers were dried over anhydrous Na2SO4, filtered, and concentrated. Purification by column chromatography on silica gel (petroleum ether/ethyl acetate = 8/1, v/v) afforded 4b as a light yellow solid (62.8 mg, 89% yield); mp 174-176 oC; 1H NMR (400 MHz, CDCl3): δ 8.37 (d, J = 8.0 Hz, 1H), 7.94-7.89 (m, 4H), 7.59 (d, J = 7.2 Hz, 2H), 7.52-7.49 (m, 3H), 7.36 (d, J = 7.6 Hz, 2H), 2.44 (s, 3H); 13

C{1H} NMR (100 MHz, CDCl3): δ 148.9, 147.8, 144.9, 137.6, 136.8, 132.9, 132.0, 130.3, 129.7,

129.4, 128.3, 127.2, 122.9, 21.6; HRMS (ESI, m/z) calcd for C19H16NO4S [M + H]+ 354.0795, found 354.0793. Mechanism Experiments (Scheme 2b). 2-Nitrobenzoic acid 1a (50.1 mg, 0.3 mmol), Ag2CO3 (124.1

mg,

0.45

mmol),

1,10-phenanthroline

(32.4

mg,

0.18

mmol),

sodium

4-methylbenzenesulfinate 2a (106.9 mg, 0.6 mmol), 1,1-diphenylethylene (162.1 mg, 0.9 mmol), and PhCF3 (3.0 mL) were added to a 25 mL Schlenk flask equipped with a high-vacuum PTFE valve-to-glass seal. Then the flask was sealed under air and stirred at 160 oC (oil bath) for 18 h. It was then cooled to room temperature. The cooled reaction mixture was diluted with DCM (10 mL) and filtered through a short pad of silica gel, which then was washed with more DCM (3 × 10 mL). The solvent was removed in vacuum and the mixture was isolated through column chromatography to afford 3aa (26.6 mg, 32% yield) and vinyl sulfone 5 (36.1 mg, 18% yield). (2-Tosylethene-1,1-diyl)dibenzene (5).23 Purification by column chromatography on silica gel


Page 17 of 23 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(petroleum ether/ethyl acetate = 15/1, v/v) afforded 5 as a colorless oil (36.1 mg, 18% yield); 1H NMR (400 MHz, CDCl3) δ 7.48 (d, J = 8.0 Hz, 2H), 7.40-7.35 (m, 2H), 7.32-7.28 (m, 4H), 7.21 (d, J = 7.2 Hz, 2H), 7.15 (d, J = 8.0 Hz, 2H), 7.10 (d, J = 8.0 Hz, 2H), 7.00 (s, 1H), 2.38 (s, 3H). Supporting Information: Copies of 1H,

13

C and

19

F NMR Spectrum. This material is available

free of charge via the Internet at http://pubs.acs.org. REFERENCES (1) Patai, S.; Rappoprt, Z.; Stirling, C. J. M. The Chemistry of Sulfones and Sulfoxides; Wiley: New York, 1988. (2) (a) Almirante, L.; Polo, L.; Mugnaini, A.; Provinciali, E.; Rugarli, P.; Biancotti, A.; Gamba, A.;

Murmann,

W.

Derivatives

of

Imidazole.

I.

Synthesis

and

Reactions

of

Imidazo[1,2-α]pyridines with Analgesic, Antiinflammatory, Antipyretic, and Anticonvulsant Activity. J. Med. Chem. 1965, 8, 305–312. (b) Yazdanyar, S.; Boer, J.; Ingvarsson, G.; Szepietowski, J. C.; Jemec, G. B. E. Dapsone Therapy for Hidradenitis Suppurativa: A Series of 24 Patients. Dermatology 2011, 222, 342–346. (c) Chen, Y.; Guo, H.; Cai, M.; Geng, C.; Yue, C.; Teng, C. Effect of Polyether Sulfone Resin on Micromorphology, Thermal, Mechanical, and Dielectric Properties of Epoxy–Bismaleimide Composite Material. J. Electron. Mater. 2018, 47, 6021–6027. (3) (a) Nielsen, M.; Jacobsen, C. B.; Paixão, M. W.; Holub, N.; Jørgensen, K. A. Asymmetric Organocatalytic Formal Alkynylation and Alkenylation of α,β-Unsaturated Aldehydes. J. Am. Chem. Soc. 2009, 131, 10581–10586. (b) Wang, Q.-G.; Zhou, Q.-Q.; Deng, J.-G.; Chen, Y.-C. An Asymmetric Allylic Alkylation-Smiles Rearrangement-Sulfinate Addition Sequence to Construct Chiral Cyclic Sulfones. Org. Lett. 2013, 15, 4786–4789. (4) Julia, M.; Paris, J.-M. Syntheses A L'aide De Sulfones V(+)-Methode De Synthese Generale De Doubles Liaisons. Tetrahedron Lett. 1973, 14, 4833–4836.



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(5) (a) Xiao, F.; Chen, S.; Tian, J.; Huang, H.; Liu, Y.; Deng, G.-J. Chemoselective Cross-coupling Reaction of Sodium Sulfinates with Phenols under Aqueous Conditions. Green Chem. 2016, 18, 1538–1546. (b) Liu, N.-W.; Liang, S.; Manolikakes, G. Recent Advances in the Synthesis of Sulfones. Synthesis 2016, 48, 1939–1973. (c) Liu, J; Zheng, L. Recent Advances in Transition-Metal-Mediated Chelation-Assisted Sulfonylation of Unactivated C–H Bonds. Adv. Synth. Catal. 2019, 361, 1710–1732. (d) Jiang, H.; Tang, X.; Xu, Z.; Wang, H.; Han, K.; Yang, X.; Zhou, Y.; Feng, Y.-L.; Yu, X.-Y.; Gui, Q. TBAI-Catalyzed Selective Synthesis of Sulfonamides and β-Aryl Sulfonyl Enamines: Coupling of Arenesulfonyl Chlorides and Sodium Sulfinates with tert-Amines. Org. Biomol. Chem. 2019, 17, 2715–2720. (6) (a) Su, W. An Efficient Method for the Oxidation of Sulfides to Sulfomes. Tetrahedron Lett. 1994, 35, 4955–4958. (b) Bahrami, K.; Khodaei, M. M.; Arabi, M. S. TAPC-Promoted Oxidation of Sulfides and Deoxygenation of Sulfoxides. J. Org. Chem. 2010, 75, 6208–6213. (c) Kirihara, M.; Okada, T.; Sugiyama, Y.; Akiyoshi, M.; Matsunaga, T.; Kimura, Y. Sodium Hypochlorite Pentahydrate Crystals (NaOCl·5H2O): A Convenient and Environmentally Benign Oxidant for Organic Synthesis. Org. Process. Res. Dev. 2017, 21, 1925–1937. (7) (a)

Répichet,

S.;

Roux,

C.

L.;

Hernandez,

P.;

Dubac,

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Synthesis

of of

Silver-Promoted Decarboxylative Sulfonylation of Aromatic Carboxylic

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