Note pubs.acs.org/joc
Synthetic Transformations Using Molecular Oxygen-Doped Carbon Materials Mariappan Periasamy,* Masilamani Shanmugaraja, Polimera Obula Reddy, Modala Ramusagar, and Gunda Ananda Rao School of Chemistry, University of Hyderabad, Central University P.O., Hyderabad 500046, India S Supporting Information *
ABSTRACT: Carbon materials like activated carbon (AC) undergo chemisorption with O2 to give species with electron deficiency in the carbon skeleton and negative charge at the oxygen end that upon reaction with PPh3 and benzoic acid afford Ph3PO. Whereas amine donors react with O2-chemisorbed AC and nucleophiles to give dehydrogenatively coupled products in 67−89% yields via the corresponding radical cation and iminium ion intermediates, the reactions using β-naphthoxide derivatives give the corresponding oxidatively coupled bi-2-naphthol products in 68−95% yields.
C
molecular oxygen to a greater extent than graphite does, which was reported to undergo only physisorption. The carbon skeleton of oxygen-adsorbed intermediate 3 is expected to behave like an electron acceptor, and the negatively charged oxygen is expected to undergo reaction with proton donors. Accordingly, such species are expected to react with proton-containing compounds like benzoic acid to give the corresponding hydroperoxide intermediate 4 (Scheme 2). To examine this possibility, we have performed the reaction of the activated carbon (5 g) with PPh3 (10 mmol) and benzoic acid (10 mmol). In this experiment, the triphenylphosphine oxide (Ph3PO) was isolated in 54% yield (Table 2). When the reaction was performed with water instead of benzoic acid, the Ph3PO was obtained in only 7% yield. We have observed that, in the case of carbon black (5 g) without using any proton source, Ph3PO was formed in 17% yield, whereas using graphite (5 g), no formation of the Ph3PO product was observed (Table 2). We have also observed that the carbon material isolated after the reaction with PPh3 can be reused after vacuum treatment at 200 °C and re-adsorption of molecular oxygen.3 Reaction using such reoxidized3 activated carbon with Ph3P in THF gave the Ph3PO product in 52% yield (Table 2, entry 5). We have observed that the reaction of benzylamine with molecular oxygen-adsorbed carbon materials 3 in THF solvent gives benzaldehyde in 30% yield. In the case of dibenzylamine, the benzaldehyde was obtained in 25% yield after workup. However, the NMR spectra obtained for the crude product mixture before workup and chromatography revealed the
arbon materials like activated carbon (AC) and carbon black (CB) were reported to undergo chemisorption with molecular oxygen, and graphite (Gr) undergoes physisorption.1 The characteristics of carbon materials and chemistry of their surface depend on the heteroatom presence that is in turn dependent on the nature of the materials and methods used for their preparation.2 The surface chemistry of the carbon materials (CM) also depends on the nature and presence of graphene edge sites. Also, it was suggested that the heteroatom (like oxygen) free graphene edge sites in carbon materials are not hydrogen-terminated or free radicals; instead, the edge sites are aryne-like armchair and carbene-like zigzag sites, but available evidence points to predominantly carbene-like zigzag sites 1 (Scheme 1).2 Evidence that chemisorption of molecular oxygen by activated carbon fiber materials leads to species with electron deficiency in the material and negative charge at the oxygen end has been published.1 Accordingly, the transfer of an electron from the triplet radical carbon site in 2 to the terminal oxygen resulting in intermediate 3 containing delocalized positive charge with negative charge on the terminal oxygen may be visualized as shown in Scheme 1. It is our goal to design experiments for practical utilization of oxygen-adsorbed species like 3 in synthetic transformations. Herein, we wish to report details of investigations of molecular oxygen-adsorbed carbon materials for use in the development of new synthetic methods involving reaction with electron rich compounds. Initially, we performed several experiments to assess the extent of adsorption of molecular oxygen on carbon materials. The results are summarized in Table 1. The results indicate that activated carbon and carbon black samples adsorb © 2017 American Chemical Society
Received: February 20, 2017 Published: April 17, 2017 4944
DOI: 10.1021/acs.joc.7b00405 J. Org. Chem. 2017, 82, 4944−4948
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The Journal of Organic Chemistry Scheme 1. Oxygen Oxidation Reaction at Zigzag Sites of the Carbon Materials
Table 1. Adsorption of Molecular Oxygen on Carbon Materialsa entry
CM (g)
oxygen-adsorbed CM (g)
adsorbed O2 (mmol)
1
AC (1) CB (1) Gr (1) AC (2) CB (2) AC (3) CB (3) AC (4) CB (4) AC (5) CB (5) AC (10) CB (10) AC (15)
1.034 1.053 1.000 2.071 2.078 3.092 3.119 4.120 4.152 5.175 5.190 10.203 10.236 15.312
1.06 1.65 − 2.22 2.43 2.88 3.72 3.75 4.75 5.46 5.93 6.34 7.37 9.75
2 3 4 5 6 7
Table 2. Reaction of Molecular Oxygen-Doped Carbon Material 3 with Benzoic Acid and PPh3a
entry
CM (g)
benzoic acid (mmol)
Ph3P (mmol)
THF (mL)
Ph3PO yield (%)b
1 2 3 4 5c
AC (5) CB (5) Gr (5) CB (5) AC (5)
10 10 0 0 10
10 10 10 10 10
20 150 20 150 20
54 47 trace 17 52
a
The reactions were performed by using benzoic acid (10 mmol) and PPh3 (10 mmol) at 25 °C. bYield. cThe reaction was performed with reoxidized activated carbon.
Scheme 3. Dehydrogenative Cross Coupling Reaction in the Presence of Oxygen-Adsorbed Activated Carbon
a
Carbon materials (CM; AC, activated carbon; CB, carbon black; Gr, graphite) were heated at 200 °C under high vacuum for 2 h and cooled to 25 °C under N2. The dry oxygen was passed through the carbon materials for 1 h at 25 °C.
presence of the imine and benzaldehyde products (S13, Supporting Information). Presumably, the reaction may give an amine radical cation followed by formation of imine, which after reaction with water yields benzaldehyde. The EPR spectrum recorded after addition of amines to oxygen-adsorbed activated carbon indicated the presence of paramagnetic species (S4, 1.5, Supporting Information). We have also performed a series of experiments using Nphenyl tetrahydroisoquinoline 6 and activated carbon (1 g) in organic transformations as outlined in Scheme 3. For example, when the reaction was performed using N-phenyl tetrahydroisoquinoline 6 and 2 equiv of nitromethane in a DMSO solvent, the dehydrogenative cross coupling product 7 was obtained in 89% yield. The product 7 was not formed in the absence of activated carbon. Use of other nucleophilic reagents like pyrrole and TMSCN gave the corresponding coupling products 8 and 9 in 75 and 67% yields, respectively. The oxidized amide derivative 10 was obtained in 72% yield without using a nucleophile. A tentative mechanism involving the amine radical cation and iminium ions may be considered to rationalize these transformations (Scheme 4). The formation of paramagnetic species
upon addition of the amine 6 was confirmed by EPR spectroscopy (S4, 1.6, Supporting Information). The reaction of recovered and reoxidized activated carbon3 with N-phenyl tetrahydroisoquinoline 6 and nitromethane gave the coupled product 7 in 86% yield. To examine the effect of the radical scavenger like TEMPO on the products, we performed the reaction of N-phenyl tetrahydroisoquinoline 6 and nitromethane with oxygen-doped carbon materials in the presence of TEMPO. In this case, the coupled product 7 was isolated in 93% yield. However, it is to be noted that the TEMPO+ intermediate was reported to react with the amine 6 to give product 7.4 Accordingly, the results indicate the formation of the TEMPO+ intermediate in the reaction of oxygen-adsorbed activated carbon 3 with the radical scavenger TEMPO (S4, 1.7, Supporting Information).
Scheme 2. Reaction of Oxygen-Doped Carbon Material with PPh3
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The Journal of Organic Chemistry
activated carbon was used, the bi-2-naphthol product was obtained in 95% yield (Table 3, entry 4). We have also observed that the 2-naphthol 17a undergoes oxidative coupling reaction in the presence of carbon black (2 g) to give bi-2-naphthol 18a in 70% yield under the same conditions, whereas no bi-2-naphthol 18a product formed when the reaction was performed using graphite (2 g), again indicating that molecular oxygen is mainly physisorbed in the case of graphite. In the absence of carbon additives, the bi-2naphthol product 18a was not formed. The substituted 2naphthol derivatives 17b and 17c gave the corresponding bi-2naphthol derivatives 18b and 18c in 83 and 68% yields, respectively (Table 3, entries 5 and 6) . We have also observed that the bi-2-naphthol product 18a was obtained in 93% yield when the recovered and reoxidized3 activated carbon was reused in this transformation (Table 3, entry 9). The oxidative coupling reactions of 2-naphthol 17a using molecular oxygen-adsorbed carbon materials can be explained by considering the mechanism outlined in Scheme 5. Initial
Scheme 4. Tentative Mechanism for Cross Dehydrogenative Coupling Reaction
Previously, methods were reported for the cross coupling of tertiary amines in the presence of Fe- and Cu-based oxidants.5,6 Also, metal free cross dehydrogenative coupling reactions of tertiary amines using I2/O2 and eosin/visible light were also reported.7 This simple alternative method involving activated carbon for dehydrogenative cross coupling reactions has good synthetic potential. We have also undertaken efforts toward the use of molecular oxygen-doped carbon materials in oxidative coupling reactions. We have performed the reaction of 2-naphthol 17a using 1 g of oxygen-doped AC in solvents like THF, methanol, and toluene, but only in toluene was the bi-2-naphthol 18a obtained in 25% yield (Table 3, entry 1). When the reaction was performed in the presence of t-BuOK as a base, the yield increased to 48%. The yield further improved to 67% when the reaction with tBuOK was performed in THF, presumably because of the greater solubility of t-BuOK in THF solvent. When 2 g of
Scheme 5. Tentative Mechanism for Oxidative Coupling of 2-Naphtholate 19
deprotonation of the 2-naphthol 17a by t-BuOK base would give the 2-naphtholate 19 that could transfer one electron to the positively charged superoxide radical-bound carbon material 3 to give the naphtholate radical 21. Dimerization of this naphtholate radical 21 followed by aromatization would give the bi-2-naphthol product 18a (Scheme 5). The formation of paramagnetic species upon addition of 2naphthol and KOtBu was confirmed by EPR spectroscopy (S4, 1.8, Supporting Information). The coupled product 18a was not formed when the reaction was performed in the presence of TEMPO, indicating the expected TEMPO+ oxonium ion intermediate formed in the reaction of TEMPO with oxygendoped activated carbon does not oxidize 2-naphtholate 19. Previously, methods for oxidative coupling of 2-naphthol were reported using FeCl3·6H2O and Cu−amine complexes.8−10 Recently, Wang et al.11 reported the coupling of 2-naphthol using m-CPBA and FeCl3 as catalysts. Graphene oxide-BF3-catalyzed oxidative coupling of electron rich aromatics was also reported,12 but the preparation of such graphene oxide requires harsh conditions compared to the simple method for adsorption of O2 to prepare the oxygendoped activated carbon 3 reported here. In summary, convenient methods have been developed for practical use of molecular oxygen-doped, metal free, and reusable carbon materials like activated carbon, carbon black, and graphite. The reaction of activated carbon with Ph3P gave Ph3PO in 54% yield. Whereas benzylamine and dibenzylamine undergo oxidative cleavage to give benzaldehyde in 25− 30% yield, the reaction of N-aryl isoquinoline with oxygendoped carbon materials leads to the formation of the radical cation intermediates that give the corresponding iminium ions
Table 3. Reaction of Molecular Oxygen-Adsorbed Carbon Materials with 2-Naphthol Derivativesa
entry d
1 2 3 4 5 6 7e 8 9f
CM (g) AC AC AC AC AC AC AC CB AC
(1) (1) (1) (2) (2) (2) (2) (2) (2)
SMb (2 mmol)
solvent (mL)
productc
yield (%)
17a 17a 17a 17a 17b 17c 17a 17a 17a
toluene (15) toluene (15) THF (15) THF (30) THF (30) THF (30) THF (30) THF (45) THF (30)
18a 18a 18a 18a 18b 18c 18a 18a 18a
25 48 67 95 83 68 76 70 93
Reactions were performed at 25 °C for 48 h using 2 mmol of tBuOK. bSM indicates starting material 2-napthol derivatives 17. c Product: bi-2-naphthol derivatives 18. dt-BuOK was not used. eThe reaction was performed for 24 h. fThe reaction was performed using recovered and reoxidized activated carbon. a
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phenyl tetrahydroisoquinoline (0.5 mmol) and a nucleophile (1 mmol) in DMSO. The reaction mixture was stirred for an additional 48 h. After that, 15 mL of EtOAc was added and the mixture stirred for an additional 0.5 h. The reaction mixture was filtered and washed several times with EtOAc and H2O. The organic layer was extracted with EtOAc, washed with brine, and then dried over anhydrous Na2SO4. The solvent was evaporated under vacuum, and the crude mixture was chromatographed on silica gel using a hexane/ethyl acetate (90:10) eluent to isolate the pure compound. 1-(Nitromethyl)-2-phenyl-1,2,3,4-tetrahydroisoquinoline (7). Brown solid: mp 92−94 °C (lit.5 89−90 °C); 0.119 g (89% yield); 1 H NMR (400 MHz, CDCl3) δ 7.29−7.18 (m, 5H), 7.14−7.13 (d, J = 6.8 Hz, 1H), 6.98 (d, J = 8 Hz, 2H), 6.85 (t, J = 7.2 Hz, 1H), 5.55 (t, J = 7 Hz, 1H), 4.95−4.85 (m, 1H), 4.59−4.54 (m, 1H), 3.79−3.59 (m, 2H), 3.21−3.05 (m, 1H), 2.87−2.78 (m, 1H); 13C{1H} NMR (100 MHz, CDCl3) δ 148.5, 135.3, 133.0, 130.0, 129.2, 128.2, 127.0, 126.7, 119.5, 115.2, 78.8, 58.2, 42.1, 26.5; IR (KBr) 3063, 3030, 2964, 2915, 1605, 1545, 1496, 1380, 1003, 899, 756 cm−1. 1-(1H-Indol-3-yl)-2-phenyl-1,2,3,4-tetrahydroisoquinoline (8).14 Pale yellow solid: mp 175−177 °C; 0.103 g (75% yield); 1H NMR (400 MHz, CDCl3) δ 7.85 (s, 1H), 7.60 (d, J = 8 Hz, 1H), 7.34−7.27 (m, 4H), 7.23−7.18 (m, 4H), 7.09−7.06 (m, 3H), 6.83 (t, J = 7.2 Hz, 1H), 6.62 (s, 1H), 6.22 (s, 1H), 3.68−3.65 (m, 2H), 3.15−3.07 (m, 1H), 2.88−2.81 (m, 1H); 13C{1H} NMR (100 MHz, CDCl3) δ 149.8, 137.5, 136.6, 135.6, 129.3, 128.9, 128.1, 126.7, 126.5, 125.8, 124.2, 122.1, 120.1, 119.7, 119.3, 118.2, 115.9, 111.1, 56.7, 42.3, 26.7; IR (KBr) 3408, 3058, 2915, 2838, 1704, 1589, 1501, 1452, 1348, 1222, 932, 740 cm−1. 2-Phenyl-1,2,3,4-tetrahydroisoquinoline-1-carbonitrile (9). Pale yellow solid: mp 94−96 °C (lit.7a 98−99 °C); 0.078 g (67% yield); 1 H NMR (400 MHz, CDCl3) δ 7.42−7.38 (m, 2H), 7.35−7.26 (m, 4H), 7.13 (d, J = 8 Hz, 1H), 7.06 (t, J = 7.4 Hz, 1H), 5.55 (s, 1H), 3.83−3.78 (m, 1H), 3.55−3.48 (m, 1H), 3.23−3.14 (m, 1H), 3.02− 2.96 (m, 1H); 13C{1H} NMR (100 MHz, CDCl3) δ 148.4, 134.7, 129.6, 129.4, 128.8, 127.1, 126.9, 121.9, 117.8, 117.6, 53.2, 44.2, 28.6; IR (KBr) 3041, 2926, 2838, 1742, 1600, 1496, 1463, 1375, 1205, 1145, 1030, 942, 745, 695 cm−1. 2-Phenyl-3,4-dihydroisoquinolin-1(2H)-one (10). White solid: mp 76−78 °C (lit.15 83−89 °C); 0.080 g (72% yield); hexane/ethyl acetate (80:20); 1H NMR (400 MHz, CDCl3) δ 8.18 (d, J = 7.6 Hz, 1H), 7.45−7.34 (m, 5H), 7.27 (t, J = 7 Hz, 3H), 4.01 (t, J = 6.4 Hz, 2H), 3.16 (t, J = 6.4 Hz, 2H); 13C{1H} NMR (100 MHz, CDCl3) δ 164.2, 143.1, 138.3, 132.0, 129.7, 128.9, 128.8, 127.2, 127.0, 126.3, 125.3, 49.4, 28.7; IR (KBr) 3063, 3041, 2964, 2931, 1660, 1599, 1490, 1408, 1325, 1254, 1029, 739, 690 cm−1. General Procedure for Cross Dehydrogenative Coupling of N-Phenyl Tetrahydroisoquinoline with Activated Carbon and a TEMPO Radical Scavenger. In a 25 mL RB flask, activated carbon (1 g) was heated at 200 °C under high vacuum (0.001 mmHg) for 2 h. After the RB flask was cooled to room temperature under a nitrogen atmosphere, the contents were saturated with dry air for 1 h. To this was added TEMPO (1 mmol) in a DMSO (4 mL) solvent, and the mixture was stirred for 1 h. Then, N-phenyl tetrahydroisoquinoline (0.5 mmol) and nitromethane (1 mmol) were added. The reaction mixture was stirred for an additional 48 h. After that, 15 mL of EtOAc was added and the mixture stirred for an additional 0.5 h. The reaction mixture was filtered and washed several times with EtOAc and H2O. The organic layer was extracted with EtOAc, washed with brine, and then dried over anhydrous Na2SO4. The solvent was evaporated under vacuum, and the crude mixture was chromatographed on silica gel using a hexane/ethyl acetate eluent to isolate pure compound 7 in 93% yield. The reaction of activated carbon in the presence of TEMPO may lead to the formation of activated carbon−TEMPO oxonium ion paramagnetic species, which may lead to the formation of product 7. General Procedure for Oxidative Coupling of 2-Naphthol Derivatives with Activated Carbon. In a 50 mL RB flask, the 2naphthol (17a−17c) (2 mmol) was dissolved in THF (30 mL) under a nitrogen atmosphere. To this was added t-BuOK (2 mmol), and the contents were stirred for ∼1 h followed by addition of activated carbon (2 g). The reaction mixture was stirred for an additional 48 h. The
that in turn react with certain nucleophilic reagents to give the corresponding addition products in 67−89% yield. Also, in the presence of t-BuOK, 2-naphthol derivatives undergo oxidative coupling reaction to give bi-2-naphthol derivatives in 68−95% yield. The activated carbon could be recovered, redoped with molecular oxygen, and reused for these organic transformations. Further systematic studies of the reactions of the oxygen-doped carbon materials with electron-donating organic compounds are expected to lead to the discovery of several new organic transformations.
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EXPERIMENTAL SECTION
General Information. N-Phenyl tetrahydroisoquinoline 6 was prepared following a literature procedure.13 Melting points were determined using a capillary point apparatus. IR (KBr) spectra were recorded on a FT-IR spectrophotometer with polystyrene as a reference. 1H NMR (400 MHz) and 13C{1H} NMR (100 MHz) spectra were recorded with chloroform-d as a solvent and TMS as a reference (δ = 0 ppm). The chemical shifts are expressed in δ downfield from the signal of internal TMS. EPR spectra was recorded in a spectrometer equipped with an EMX micro X source for X band measurement using Xenon 1.1b.60 software provided by the manufacturer. Activated carbon was heated at 200 °C under reduced pressure (0.001 mmHg) in a vacuum oven and stored under dry nitrogen. Toluene and THF were freshly distilled over sodium benzophenone ketyl before use. Analytical thin layer chromatographic tests were performed on glass plates (3 cm × 10 cm) coated with 250 μm silica gel-G and GF254 containing 13% calcium sulfate as a binder. The spots were visualized by a short exposure to iodine vapor or UV light. Column chromatography was performed using silica gel (100− 200 mesh). General Procedure for Reaction of Molecular OxygenDoped Carbon Materials with Ph3P in the Presence of Benzoic Acid. In a 50 mL RB flask, activated carbon (5 g) heated at 200 °C under high vacuum (0.001 mmHg) for 2 h. After the RB flask was cooled to room temperature under a nitrogen atmosphere, the contents were saturated with dry air for 1 h. To this were added Ph3P (2.62 g 10 mmol) and benzoic acid (1.221 g, 10 mmol) in THF. The reaction mixture was stirred for a further 24 h. The reaction mixture was filtered, and the organic layer was separated. The solvent was evaporated under reduced pressure, and the crude product Ph3PO was purified by silica gel column chromatography using hexane as an eluent to give a white solid: 0.501 g, 54% yield; 1H NMR (400 MHz, CDCl3) δ 7.67−7.62 (m, 1H), 7.52−7.48 (m, 1H), 7.43−7.40 (m, 1H); 13C{1H} NMR (100 MHz, CDCl3) δ 133.0, 132.1, 132.0, 131.9, 128.5, 128.4; 31P NMR (162 MHz, CDCl3) δ 29.3; IR (neat, cm−1) 3073, 3046, 1599, 1489, 1435, 1308, 1188, 1117, 1002. General Procedure for Oxidation of Benzylamine Derivatives with Activated Carbon. In a 25 mL RB flask, activated carbon (1 g) was heated at 200 °C under high vacuum (0.001 mmHg) for 2 h. After the RB flask was cooled to room temperature under a nitrogen atmosphere, the contents were saturated with dry air for 1 h. To this benzylamine were added derivatives (1 mmol) in a THF solvent. The reaction mixture was stirred for a further 24 h. After that, the reaction mixture was filtered and the organic layer was evaporated. Then the NMR spectrum was recorded for the crude compound to show the formation of both imine and benzaldehyde (S13, Supporting Information). The crude reaction mixture was washed several times with EtOAc and H2O. The organic layer extracts with EtOAc were washed with brine and then dried over anhydrous Na2SO4. The solvent was evaporated under vacuum, and the crude mixture was chromatographed on silica gel using a hexane/ethyl acetate (90:10) eluent to give pure benzaldehyde. General Procedure for Cross Dehydrogenative Coupling of N-Phenyl Tetrahydroisoquinoline Derivatives with Activated Carbon. In a 25 mL RB flask, activated carbon (1 g) was heated at 200 °C under high vacuum (0.001 mmHg) for 2 h. After the RB flask was cooled to room temperature under a nitrogen atmosphere, the contents were saturated with dry air for 1 h. To this were added N4947
DOI: 10.1021/acs.joc.7b00405 J. Org. Chem. 2017, 82, 4944−4948
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The Journal of Organic Chemistry reaction mixtures were filtered and washed several times with DCM and H2O. The organic layer was extracted with DCM, washed with brine, and then dried over anhydrous Na2SO4. The solvent was evaporated under vacuum, and the crude mixture was chromatographed on silica gel using a hexane/ethyl acetate (85:15) eluent to isolate the pure compound. 1,1′-Bi-2,2′-naphthol (18a). Colorless solid: 0.275 g (95% yield); mp 217−219 °C (lit.11 216−218 °C); 1H NMR (400 MHz, CDCl3) δ 7.97−7.95 (d, J = 8 Hz, 2H), 7.90−7.88 (d, J = 8 Hz, 2H), 7.39−7.33 (m, 4H), 7.33−7.29 (m, 2H), 7.17−7.15 (d, J = 8 Hz, 2H), 5.09 (s, 2H); 13C{1H} NMR (100 MHz, CDCl3) δ 152.6, 133.4, 131.4, 129.4, 128.4, 127.5, 124.2, 124.0, 117.7, 110.8; IR (neat) 3484, 3402, 3040, 1621, 1599, 1517, 1468, 1386, 1325, 1271, 1221, 1183, 1145 cm−1. 6,6′-Dibromo-1,1′-bi-2,2′-naphthol (18b). Colorless solid: 0.372 g (83% yield); mp 198−200 °C (lit.11 200−202 °C); 1H NMR (400 MHz, CDCl3) δ 8.06−8.04 (m, 2H), 7.91−7.87 (m, 2H), 7.41−7.35 (m, 4H), 6.98−6.94 (m, 2H), 5.04 (s, 2H); 13C{1H} NMR (100 MHz, CDCl3) δ 152.9, 131.9, 130.8, 130.7, 130.5, 130.4, 125.8, 118.9, 118.02, 110.6; IR (neat) 3451, 1604, 1588, 1495, 1380, 1347, 1215, 1160, 1122 cm−1. Dimethyl 2,2′-Dihydroxy-1,1′-binaphthyl-3,3′-dicarboxylate (18c). Yellow solid: 0.275 g (68% yield); mp 284−286 °C (lit.11 285−287 °C); 1H NMR (400 MHz, CDCl3) δ 10.77 (s, 2H), 8.71 (s, 2H), 7.95−7.93 (m, 2H), 7.37−7.35 (m, 4H), 7.20−7.18 (m, 2H), 4.06 (s, 6H); 13C{1H} NMR (100 MHz, CDCl3) δ 170.6, 154.0, 137.2, 132.9, 129.8, 129.5, 127.2, 124.7, 124.0, 117.0, 114.1, 52.7; IR (neat) 3183, 2947, 1676, 1506, 1441, 1326, 1293, 1221, 1150, 1084 cm−1.
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material for 1 h. This oxygen-adsorbed activated carbon sample was reused for synthetic transformations. (4) Xue, D.; Long, Y.-Q. J. Org. Chem. 2014, 79, 4727. (5) Li, Z.; Li, C.-J. J. Am. Chem. Soc. 2005, 127, 3672. (6) (a) Ratnikov, M. O.; Xu, X.; Doyle, M. P. J. Am. Chem. Soc. 2013, 135, 9475. (b) Brzozowski, M.; Forni, J. A.; Savage, G. P.; Polyzos, A. Chem. Commun. 2015, 51, 334. (c) Kumaraswamy, G.; Murthy, A. N.; Pitchaiah, A. J. Org. Chem. 2010, 75, 3916. (7) (a) Dhineshkumar, J.; Lamani, M.; Alagiri, K.; Prabhu, K. R. Org. Lett. 2013, 15, 1092. (b) Hari, D. P.; König, B. Org. Lett. 2011, 13, 3852. (8) Ding, K.; Wang, Y.; Zhang, L.; Wu, Y.; Matsuura, T. Tetrahedron 1996, 52, 1005. (9) Brussee, J.; Groenendijk, J. K. G.; te Koppele, J. M.; Jansen, A. S. A. Tetrahedron 1985, 41, 3313. (10) Doussot, J.; Guy, A.; Ferroud, C. Tetrahedron Lett. 2000, 41, 2545. (11) Wang, K.; Lu, M.; Yu, A.; Zhu, X.; Wang, Q. J. Org. Chem. 2009, 74, 935. (12) Morioku, K.; Morimoto, N.; Takeuchi, Y.; Nishina, Y. Sci. Rep. 2016, 6, 25824. (13) Tanoue, A.; Yoo, W.-J.; Kobayashi, S. Org. Lett. 2014, 16, 2346. (14) Liu, P.; Zhou, C.-Y.; Xiang, S.; Che, C.-M. Chem. Commun. 2010, 46, 2739. (15) Zhang, W.; Yang, S.; Shen, Z. Adv. Synth. Catal. 2016, 358, 2392.
ASSOCIATED CONTENT
S Supporting Information *
The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.joc.7b00405. Copies of the EPR, 1H NMR, and 13C{1H} NMR spectra of the products (PDF)
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AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected]. ORCID
Mariappan Periasamy: 0000-0001-6376-6589 Notes
The authors declare no competing financial interest.
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ACKNOWLEDGMENTS We thank the DST-SERB for its support via a J. C. Bose National Fellowship (SR/S2/JCB-33/2005) and Green Chemistry programs (SB/S5/GC-01/2014) and the CSIR-HRDG for its support by a research grant (02/0176/14/EMR-II). We also thank the DST for its support of the School of Chemistry under the FIST and IRPHA programs, and support of the UGC under UPE and CAS programs to the School of Chemistry is also gratefully acknowledged. M.S., P.O.R., M.R., and G.A.R. thank the CSIR and UGC (New Delhi) for research fellowships.
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REFERENCES
(1) Sumanasekera, G. U.; Chen, G.; Takai, K.; Joly, J.; Kobayashi, N.; Enoki, T.; Eklund, P. C. J. Phys.: Condens. Matter 2010, 22, 334208. (2) Radovic, L. R.; Bockrath, B. J. Am. Chem. Soc. 2005, 127, 5917. (3) Reuse of oxidized activated carbon. After the reaction with activated carbon, the resulting carbon materials were filtered and washed several times with organic solvents (THF followed by acetone) to remove the trace amount of organic products. Then, the sample was heated at 200 °C under high vacuum for 2 h and cooled to rt under N2. The dry oxygen was adsorbed by passing it through the carbon 4948
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