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Article

Selective C-O Coupling Reaction of N-Methoxy Arylamides and Arylboronic Acids Catalyzed by Copper Salt

by
Ying Wang
,
Huilin Xie
,
Kunming Liu
*,
Jinhui Li
* and
Jin-Biao Liu
*
Jiangxi Provincial Key Laboratory of Functional Molecular Materials Chemistry, Jiangxi University of Science and Technology, 86 Hongqi Road, Ganzhou 341000, China
*
Authors to whom correspondence should be addressed.
Catalysts 2022, 12(10), 1278; https://doi.org/10.3390/catal12101278
Submission received: 24 September 2022 / Revised: 17 October 2022 / Accepted: 17 October 2022 / Published: 19 October 2022
(This article belongs to the Special Issue Catalyzed Carbon-Heteroatom Bond Formation)
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Abstract

:
Herein, we report a copper-catalyzed C-O cross-coupling of N-methoxy amides and arylboronic acids for the synthesis of aryl-N-methoxy arylimides. The fully selective O-arylation of the N-methoxy amides is found to be greatly prompted by the inexpensive and commercially available CuI. The reaction conditions tolerate a variety of functional groups and promote different reactivities depending on the electronic and steric properties of the distorted substrates.

Graphical Abstract

1. Introduction

The transition-metal-catalyzed cross-coupling of amides has emerged as a powerful tool for the construction of carbon–carbon and carbon–heteroatom bonds, enabling the broad application of traditionally inert amides in the synthesis of pharmaceutical agents, natural products, agrochemicals and functional materials [1,2,3,4]. Palladium-catalyzed Buchwald–Hartwig couplings [5], as well as copper-catalyzed Ullmann couplings [6] and Goldberg couplings [7], employ aryl halides as the arylating reagents of the amides. Nevertheless, high temperatures, stoichiometric amounts of basic additives and specific halide substrates are required in such reactions, thereby limiting the further application of these methodologies [8,9,10].
In 1998, Chan and Lam reported the first example of the N/O-arylation of amides using aryl boronic acids as the substrate [11]. Due to their environmental benefits, functional group tolerance and commercial availability, arylboronic acids have been successfully utilized as arylating reagents for the direct cross-coupling of amides in recent years [12,13,14]. The palladium- and nickel-catalyzed Suzuki–Miyaura coupling of amides via N–C(O) acyl cleavage are representative approaches for C-arylation (Scheme 1a) [15,16,17]. To date, significant progress has been reported in the use of amide derivatives, including N-acetyl-amides [18], N-acylsuccinimides [19], N, N-di-Boc amides [20], and N-acyl-pyrroles [21] as cross-coupling partners. Copper-mediated Chan–Lam reactions are an efficient protocol for the N-arylation of amides [22,23,24,25], and encouraging results have been obtained for both amides and boronic acid substrates over the past decades (Scheme 1b). In addition to amides, O-protected hydroxamic acids have also been used as an amide source. In 2008, the Liebeskind group [26] reported the C-N cross-coupling of O-acetyl hydroxamic acids with arylboronic acids which was promoted by stoichiometric copper. A novel mechanochemical synthesis of N-aryl amides from O-pivaloyl hydroxamic acids and arylboronic acids in the presence of stoichiometric copper has also been developed by the Vilela and Lloyd groups [27]. Although N-arylation exhibits a high amenability to O-protected hydroxamic acids, the methods for selective O-arylation are noticeably lacking. Thus, the development of new amide precursors that are compatible with various reaction pathways is required to fully exploit the potential of the amides in cross-coupling reactions.
In 2021, our group [28] developed an efficient iron-catalyzed synthesis of N-aryl amides from N-methoxy amides and arylboronic acids (Scheme 1c). In the presence of an Fe catalyst, N-methoxy amides were converted into methyloxonio amides via 1, 2-H migration and subsequent C-N construction steps. Based on our experience in amide bond conversion [29,30,31] and inspired by the structural features of N-methoxy amides [32,33], we questioned whether the amide group that is linked to a methoxy substituent could be strategically employed to accomplish C-O cross-coupling in the form of hydroxamic acid. To our delight, a selective C-O coupling of N-methoxy amides with arylboronic acids occurred in the presence of a copper salt (Scheme 1d).

2. Results and Discussion

We first examined the cross-coupling reaction of N-methoxybenzamide (1a) with p-tolylboronic acid (2a) under a variety of conditions. The selected optimization results are shown in Table 1. We were delighted to find that the desired p-tolyl (E)-N-methoxybenzimidate 3a was obtained with a promising 28% yield using Cu(OAc)2·H2O (20 mol%) and K2CO3 (2 equiv.) in dichloroethane (DCE) at 130 °C, whereas the N-arylation product 4a was obtained a 6% yield (Entry 1, Table 1). As we were encouraged by this preliminary result, various bases were tested. Na3PO4·12H2O appeared to be the best base for the coupling reaction since 3a was obtained in lower yields using the common bases such as K2CO3, Et3N, KOH, Cs2CO3, t-BuOK, and Na2CO3 under otherwise identical conditions (Entries 2–9, Table 1). Interestingly, we found that the solvent choice had a major impact on the reaction. THF, acetone, EtOH, DMF, 1, 4-dioxane, DMSO, and MeCN had a deleterious effect on the cross-coupling, while EA, toluene, and Et2O provided less satisfactory results than DCE did (Entries 10–19, Table 1). Further studies were focused on the reaction temperature (Entries 20–24, Table 1). When the temperature was elevated to 130 °C, the yield of 3a was improved to 48%, while 4a was obtained in a yield of less than 5%. Unfortunately, higher temperatures did not lead to substantially higher yields due to the inevitable decomposition of p-tolylboronic acid. With the optimal conditions in hand, other copper salt catalysts including CuI, CuBr, and CuCl were also explored (Entries 25–27, Table 1). Encouragingly, 3a was obtained selectively in a 70% yield in the presence of CuI. Finally, the optimal reaction conditions for the selective C-O coupling of N-methoxyarylimides with arylboronic acids were found to be 20 mol% CuI and two equiv. Na3PO4·12H2O in DCE at 130 °C.
The evaluation of the C-O cross-coupling strategy was first examined by screening a range of electronically and sterically distorted boronic acids under the optimized conditions (Scheme 2). The reaction tolerates a wide range of arylboronic acids bearing sensitive functional groups, such as aryl halide (2g), ester (2h) and nitriles (2k), which act as synthetic handles for further functionalization. Aromatic boronic acids bearing moderate electron-donating (2a, 2b) and electron-withdrawing (2g, 2h, 2k) groups produced products in satisfactory yields, while the strong electronic effect in the arylboronic acids (2c, 2i, 2j) were detrimental to the reaction. An ortho-substituted electron-withdrawing group (2j) is more beneficial to the C-O coupling of boric acid substrates than the electron-donating group is (2e, 2f). When the R group was a 2-naphthyl group, N-aryl amide 2l could also be prepared in a 40% yield. However, alkylboronic acids (2m, 2n) were inert in this cross-coupling, which may be due to their tendency to undergo β-H elimination.
Subsequently, the reaction scope with respect to the N-methoxy amide component was examined (Scheme 3). Electron-rich N-methoxy amides bearing a p-methoxy group (1p) or electron-deficient N-methoxy amides bearing halides (1r–1t, 1z) smoothly gave their corresponding C-O coupling products in moderate-to-good yields (38–69%). Of note, the ideal leaving groups, -Br (1r) and -Cl (1s), which are commonly used in Suzuki–Miyaura couplings were preserved, displaying the high selectivity of the C-O cross-coupling reaction. Nevertheless, the reaction was incompatible with an N-methoxy amide bearing a strong electron-donating substituent (-NO2, 1q). Sterically hindered (1u) and heterocyclic (1v) N-methoxy amides showed a moderate tolerance under the optimized conditions. Unfortunately, the attempts to explore the alkylated substrates (1w, 1x, 1y) failed, implying that the reaction was very sensitive to the alkyl groups of the N-methoxy amides.
To gain an insight into the reaction mechanism, a number of control experiments were carried out. When N-methoxy-N-methylbenzamide was utilized as the starting material, the desired O-arylation product was not formed (Scheme 4a). Similarly, N-phenylbenzamide and benzamide were inert under these copper-catalyzed C-O coupling conditions (Scheme 4b,c). Taken together, these findings suggest that the N-methoxy group increased the electron cloud density on the carbonyl oxygen atom, facilitating the tautomerization of the N-methoxy amides to the O-protected hydroxamic acids, thus changing the coupling reaction site from the nitrogen atom to the oxygen atom. Furthermore, we conducted an experiment under an N2 atmosphere instead of in air, and the expected product was not obtained, indicating that oxygen is required for this reaction to occur (Scheme 4d).
In light of the above results and the previous research [34,35,36,37], a plausible reaction mechanism has been proposed (Figure 1). Cu(I) is firstly oxidized into a Cu(II) species B, which then undergoes transmetalation with arylboronic acid 2 to form aryl-Cu(II) intermediate C. Subsequently, N-methoxy amide 1 undergoes H-migration and anion exchange with C to generate Cu(II) complex D under the alkaline conditions. The oxidation of D results in the formation of Cu(III) complex E, which is followed by a reductive elimination to regenerate the Cu(I) catalyst and produce the desired product 3.

3. Materials and Methods

3.1. General Information

Unless otherwise noted, all of the reagents were purchased from Shanghai Aladdin Bio-Chem Technology Co., Ltd. (Shanghai, China) and used without purification. Purification of products was conducted by flash chromatography on silica gel (200–300 mesh). Nuclear magnetic resonance (NMR) spectra were measured on a Bruker Avance III 400 (Bruker, Billerica, MA, USA). The 1H-NMR (400 MHz) chemical shifts were obtained relative to CDCl3 as the internal reference (CDCl3: δ 7.26 ppm). The 13C-NMR (100 MHz) chemical shifts were given using CDCl3 as the internal standard (CDCl3: δ 77.16 ppm). Chemical shifts are reported in ppm using tetramethylsilane as internal standard (s = singlet, d = doublet, t = triplet, q = quartet, dd = doublet of doublets, m = multiplet). HR-MS data were obtained on a VG ZAB-HS mass spectrometer, Bruker Apex IV FTMS spectrometer.

3.2. General Procedure for the Copper-Catalyzed C-O Coupling of N-Methoxy Amides

N-methoxy amide 1 (0.2 mmol), arylboronic acid 2 (0.3 mmol), CuI (20 mmol%), Na3PO4·12H2O (0.4 mmol) and dichloroethane (DCE, 2.0 mL) were added to a sealed tube. Then, the mixture was stirred at 130 °C in the air for 24 h. After the disappearance of the substrate as indicated by the TLC, the mixture was concentrated in vacuo, and the resulting crude product was purified by column chromatography to afford the products 3.

3.3. Characterization Data for Products 3a–3v

The following characterization data are shown in the Supplementary Materials.
(E)-p-tolyl N-methoxybenzimidate (3a). 1H-NMR (400 MHz, CDCl3) δ 7.63 (d, J = 7.4 Hz, 2H), 7.23 (dd, J = 15.7, 7.9 Hz, 3H), 6.95 (d, J = 8.3 Hz, 2H), 6.77 (d, J = 8.3 Hz, 2H), 3.83 (s, 3H), 2.17 (s, 3H). 13C-NMR (101 MHz, CDCl3) δ 153.18, 150.81, 132.18, 130.23, 130.19, 130.07, 128.52, 126.85, 115.75, 62.88, 20.62. HR-MS (ESI-TOF) m/z: [M + H]+ Calcd for C15H16NO2 242.1181; Found: 242.1182.
(E)-4-(tert-butyl)phenyl N-methoxybenzimidate (3b). 1H-NMR (400 MHz, CDCl3) δ 7.79–7.77 (m, 2H), 7.41–7.37 (m, 2H), 7.36 (s, 1H), 7.32–7.29 (m, 2H), 6.94–6.91 (m, 2H), 3.97 (s, 3H), 1.31 (s, 9H). 13C-NMR (101 MHz, CDCl3) δ 152.90, 150.69, 145.44, 130.21, 128.50, 126.79, 126.43, 115.15, 62.88, 34.21, 31.48. HR-MS (ESI-TOF) m/z: [M + H]+ Calcd for C18H22NO2 284.1651; Found: 284.1647.
(E)-4-Methoxyphenyl N-methoxybenzimidate (3c). 1H-NMR (400 MHz, CDCl3) δ 7.65–7.60 (m, 2H), 7.31–7.22 (m, 3H), 6.84–6.79 (m, 2H), 6.73–6.68 (m, 2H), 3.86 (s, 3H), 3.66 (s, 3H). 13C-NMR (101 MHz, CDCl3) δ 155.20, 151.11, 149.18, 130.19, 130.13, 128.49, 126.96, 117.04, 114.62, 62.85, 55.62. HR-MS (ESI-TOF) m/z: [M + H]+ Calcd for C15H16NO3 258.1130; Found: 258.1128.
(E)-Phenyl N-methoxybenzimidate (3d). 1H-NMR (400 MHz, CDCl3) δ 7.65 (d, J = 7.5 Hz, 2H), 7.30–7.22 (m, 3H), 7.18 (t, J = 7.7 Hz, 2H), 6.93 (t, J = 7.4 Hz, 1H), 6.88 (d, J = 8.4 Hz, 2H), 3.84 (s, 3H). 13C-NMR (101 MHz, CDCl3) δ 155.26, 150.50, 130.29, 130.06, 129.60, 128.54, 126.77, 122.78, 115.89, 62.89. HR-MS (ESI-TOF) m/z: [M + H]+ Calcd for C14H14NO2 228.1025; Found: 228.1020.
(E)-4-Chlorophenyl N-methoxybenzimidate (3g). 1H-NMR (400 MHz, CDCl3) δ 7.76–7.73 (m, 2H), 7.43–7.35 (m, 3H), 7.27–7.23 (m, 2H), 6.95–6.91 (m, 2H), 3.95 (s, 3H). 13C-NMR (101 MHz, CDCl3) δ 153.89, 150.12, 130.47, 129.70, 129.53, 128.61, 127.80, 126.64, 117.18, 62.94. HR-MS (ESI-TOF) m/z: [M + H]+ Calcd for C14H13NO2Cl 262.0635; Found: 262.0632.
(E)-Methyl 4-((methoxyimino)(phenyl)methoxy)benzoate (3h). 1H-NMR (400 MHz, CDCl3) δ 7.90 (d, J = 8.9 Hz, 2H), 7.68–7.64 (m, 2H), 7.33–7.25 (m, 3H), 6.92 (d, J = 8.9 Hz, 2H), 3.84 (s, 3H), 3.80 (s, 3H). 13C-NMR (101 MHz, CDCl3) δ 166.51, 158.88, 149.64, 131.69, 130.62, 129.50, 128.69, 126.51, 124.73, 115.51, 63.02, 52.09. HR-MS (ESI-TOF) m/z: [M + H]+ Calcd for C16H16NO4 286.1079; Found: 286.1080.
(E)-3-Cyanophenyl N-methoxybenzimidate (3k). 1H-NMR (400 MHz, CDCl3) δ 7.76–7.71 (m, 2H), 7.44–7.32 (m, 5H), 7.24–7.19 (m, 2H), 3.91 (s, 3H). 13C-NMR (101 MHz, CDCl3) δ 155.38, 149.25, 130.78, 130.57, 129.24, 128.75, 126.55, 126.44, 120.57, 119.11, 118.21, 113.49, 63.06. HR-MS (ESI-TOF) m/z: [M + H]+ Calcd for C15H13N2O2 253.0977; Found: 253.0977.
(E)-Naphthalen-2-yl N-methoxybenzimidate (3l). 1H-NMR (400 MHz, CDCl3) δ 7.78–7.67 (m, 4H), 7.59 (d, J = 8.2 Hz, 1H), 7.36–7.23 (m, 5H), 7.22–7.15 (m, 2H), 3.86 (d, J = 4.6 Hz, 3H). 13C-NMR (101 MHz, CDCl3) δ 153.08, 150.55, 134.16, 130.37, 130.00, 129.92, 129.84, 128.60, 127.74, 127.08, 126.77, 126.62, 124.55, 117.48, 110.85, 62.96. HR-MS (ESI-TOF) m/z: [M + H]+ Calcd for C18H16NO2 278.1181; Found: 278.1178.
(E)-4-(tert-butyl)phenyl N-methoxy-4-methylbenzimidate (3o). 1H-NMR (400 MHz, CDCl3) δ 7.62 (d, J = 8.2 Hz, 2H), 7.25 (dt, J = 3.9, 2.4 Hz, 2H), 7.12 (d, J = 8.0 Hz, 2H), 6.89–6.85 (m, 2H), 3.92 (s, 3H), 2.32 (s, 3H), 1.27 (s, 9H). 13C-NMR (101 MHz, CDCl3) δ 152.97, 150.86, 145.34, 140.45, 129.26, 127.31, 126.75, 126.42, 115.14, 62.81, 34.21, 31.49, 21.45. HR-MS (ESI-TOF) m/z: [M + H]+ Calcd for C19H24NO2 298.1807; Found: 298.1807.
(E)-4-(tert-butyl)phenyl N, 4-dimethoxybenzimidate (3p). 1H-NMR (400 MHz, CDCl3) δ 7.68–7.65 (m, 2H), 7.27–7.24 (m, 2H), 6.89 (s, 1H), 6.86 (s, 1H), 6.84 (s, 1H), 6.82 (s, 1H), 3.90 (s, 3H), 3.77 (s, 3H), 1.27 (s, 9H). 13C-NMR (101 MHz, CDCl3) δ 161.24, 152.98, 150.68, 145.33, 128.39, 126.42, 122.50, 115.14, 113.95, 62.73, 55.31, 34.21, 31.49. HR-MS (ESI-TOF) m/z: [M + H]+ Calcd for C19H24NO3 314.1756; Found: 314.1757.
(E)-4-(tert-butyl)phenyl 4-bromo-N-methoxybenzimidate (3r). 1H-NMR (400 MHz, CDCl3) δ 7.62–7.59 (m, 2H), 7.47–7.44 (m, 2H), 7.28–7.25 (m, 2H), 6.87–6.84 (m, 2H), 3.92 (s, 3H), 1.27 (s, 9H). 13C-NMR (101 MHz, CDCl3) δ 152.68, 149.89, 145.69, 131.76, 129.23, 128.27, 126.52, 124.67, 115.07, 63.01, 34.24, 31.47. HR-MS (ESI-TOF) m/z: [M + H]+ Calcd for C18H21NO2Br 362.0756; Found: 362.0759.
(E)-4-(tert-butyl)phenyl 4-chloro-N-methoxybenzimidate (3s). 1H-NMR (400 MHz, CDCl3) δ 7.69–7.65 (m, 2H), 7.31–7.25 (m, 4H), 6.87–6.84 (m, 2H), 3.92 (s, 3H), 1.27 (s, 9H). 13C-NMR (101 MHz, CDCl3) δ 152.69, 149.81, 145.68, 136.28, 128.81, 128.76, 128.06, 126.51, 115.07, 62.99, 34.24, 31.47. HR-MS (ESI-TOF) m/z: [M + H]+ Calcd for C18H21NO2Cl 318.1261; Found: 318.1260.
(E)-4-(tert-butyl)phenyl 4-fluoro-N-methoxybenzimidate (3t). 1H-NMR (400 MHz, CDCl3) δ 7.74–7.70 (m, 2H), 7.28–7.25 (m, 2H), 7.03–6.98 (m, 2H), 6.88–6.85 (m, 2H), 3.91 (s, 3H), 1.27 (s, 9H).13C-NMR (101 MHz, CDCl3) δ 165.24, 162.75, 151.31, 145.62, 128.84, 126.49, 126.37, 115.66, 115.11, 62.89, 34.23, 31.47. HR-MS (ESI-TOF) m/z: [M + H]+ Calcd for C18H21NO2F 302.1556; Found: 302.1554.
(E)-4-(tert-butyl)phenyl N-methoxy-2-naphthimidate (3u). 1H-NMR (400 MHz, CDCl3) δ 8.15 (d, J = 1.1 Hz, 1H), 7.92 (dd, J = 8.7, 1.7 Hz, 1H), 7.81–7.78 (m, 3H), 7.50–7.42 (m, 2H), 7.29–7.25 (m, 2H), 6.96–6.92 (m, 2H), 3.97 (s, 3H), 1.27 (s, 9H). 13C-NMR (101 MHz, CDCl3) δ 153.09, 150.85, 145.46, 134.16, 132.94, 128.73, 128.32, 127.73, 127.66, 127.12, 126.94, 126.48, 123.55, 115.11, 62.98, 34.23, 31.49. HR-MS (ESI-TOF) m/z: [M + H]+ Calcd for C22H24NO2 334.1807; Found: 334.1812.
(E)-4-(tert-butyl)phenyl N-methoxythiophene-2-carbimidate (3v). 1H-NMR (400 MHz, CDCl3) δ 7.30–7.25 (m, 4H), 6.96–6.90 (m, 3H), 3.90 (d, J = 1.4 Hz, 3H), 1.28 (d, J = 1.4 Hz, 9H). 13C-NMR (101 MHz, CDCl3) δ 152.91, 147.76, 145.75, 132.93, 128.62, 128.08, 127.30, 126.43, 115.15, 62.91, 34.24, 31.48.
(E)-p-tolyl 4-chloro-N-methoxybenzimidate (3z). 1H-NMR (400 MHz, CDCl3) δ 7.58 (d, J = 8.5 Hz, 2H), 7.22 (d, J = 8.6 Hz, 2H), 6.98 (d, J = 8.4 Hz, 2H), 6.76 (d, J = 8.5 Hz, 2H), 3.85 (s, 3H), 2.20 (s, 3H). 13C-NMR (101 MHz, CDCl3) δ 152.89, 149.90, 136.28, 132.44, 130.14, 128.82, 128.66, 128.10, 115.63, 63.02, 20.64. HR-MS (ESI-TOF) m/z: [M + H]+ Calcd for C15H15NO2Cl 276.0791; Found: 276.0797.

4. Conclusions

In conclusion, we have described a copper-salt-catalyzed selective C-O cross-coupling of N-methoxy amides and arylboronic acids for the synthesis of aryl-N-methoxy arylimides in moderate yields. The optimal parameters were obtained by systematically exploring the reaction conditions such as the types of catalyst and base, the applicable temperature range, and the choice of solvents. A wide range of N-methoxy amides as well as arylboronic acids can serve as viable substrates, with various functional groups being tolerated. The most obvious finding to emerge from this study is that the type of copper salt greatly affects the reaction site of the N-methoxy amides. These findings enhance our understanding of the use of N-methoxy amides, and they will serve as a foundation for the future studies on the reaction mechanism.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/catal12101278/s1. The experimental procedures and characterization (1H- and 13C-NMR, and HR-MS) for all of the products are provided in the supporting information.

Author Contributions

Conceptualization, J.-B.L. and K.L.; methodology, J.L. and Y.W.; validation, H.X.; writing—original draft preparation, J.L. and Y.W.; writing—review and editing, K.L.; supervision, J.-B.L. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the National Natural Science Foundation of China (21961014), the Jiangxi Provincial Natural Science Foundation (20202BABL213007, 20212BAB203013), the Jiangxi Provincial Key Laboratory of Functional Molecular Materials Chemistry (20212BCD42018), and the Jinggang Scholars Program in Jiangxi Province.

Data Availability Statement

Not applicable.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Cheung, C.W.; Ploeger, M.L.; Hu, X. Direct amidation of esters with nitroarenes. Nat. Commun. 2017, 8, 14878. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  2. Hili, R.; Yudin, A.K. Making carbon-nitrogen bonds in biological and chemical synthesis. Nat. Chem. Biol. 2006, 2, 284–287. [Google Scholar] [CrossRef] [PubMed]
  3. Li, G.; Szostak, M. Highly selective transition-metal-free transamidation of amides and amidation of esters at room temperature. Nat. Commun. 2018, 9, 4165. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  4. Chisholm, T.S.; Kulkarni, S.S.; Hossain, K.R.; Cornelius, F.; Clarke, R.J.; Payne, R.J. Peptide ligation at high dilution via reductive diselenide-selenoester ligation. J. Am. Chem. Soc. 2020, 142, 1090–1100. [Google Scholar] [CrossRef]
  5. Forero-Cortés, P.A.; Haydl, A.M. The 25th Anniversary of the Buchwald-Hartwig amination: Development, applications, and outlook. Org. Process Res. Dev. 2019, 23, 1478–1483. [Google Scholar] [CrossRef]
  6. Sambiagio, C.; Marsden, S.P.; Blackera, A.J.; McGowan, P.C. Copper catalysed Ullmann type chemistry: From mechanistic aspects to modern development. Chem. Soc. Rev. 2014, 43, 3525–3550. [Google Scholar] [CrossRef]
  7. Meng, T.; Zhang, Y.L.; Li, M.; Wang, X.; Shen, J.K. Synthesis of novel substituted benzimidazo[1,2-a]quinoxalin-6(5H)-ones via an intramolecular Goldberg reaction. J. Comb. Chem. 2010, 12, 222–224. [Google Scholar] [CrossRef]
  8. Meng, G.R.; Szostak, M. Palladium-catalyzed Suzuki-Miyaura coupling of amides by carbon-nitrogen cleavage: General strategy for amide N-C bond activation. Org. Biomol. Chem. 2016, 14, 5690–5707. [Google Scholar] [CrossRef]
  9. Takise, R.; Muto, K.; Yamaguchi, J. Cross-coupling of aromatic esters and amides. Chem. Soc. Rev. 2017, 46, 5864–5888. [Google Scholar] [CrossRef]
  10. Wang, C.L.; Bai, X.; Wang, R.; Zheng, X.D.; Ma, X.M.; Chen, H.; Ai, Y.; Bai, Y.J.; Liu, Y.F. Synthesis of Imatinib by C-N coupling reaction of primary amide and bromo-substituted pyrimidine amine. Org. Process Res. Dev. 2019, 23, 1918–1925. [Google Scholar] [CrossRef]
  11. Chan, D.M.T.; Monaco, K.L.; Wang, R.-P.; Winters, M.P. New N- and O-arylations with phenylboronic acids and cupric acetate. Tetrahedron Lett. 1998, 39, 2933–2936. [Google Scholar] [CrossRef]
  12. Alapati, M.L.P.R.; Abburu, S.R.; Mutyala, K.R.; Mukkamala, S.B. Copper (I) iodide-catalyzed amidation of phenylboronic acids/arylbromides using 4-dimethylaminopyridine as ligand. Synth. Commun. 2016, 46, 1242–1248. [Google Scholar] [CrossRef]
  13. Sahoo, H.; Mukherjee, S.; Grandhi, G.S.; Selvakumar, J.; Baidya, M. Copper catalyzed C-N cross-coupling reaction of arylboronic acids at room temperature through chelation assistance. J. Org. Chem. 2017, 82, 2764–2771. [Google Scholar] [CrossRef] [PubMed]
  14. Roscalesa, S.; Csáky, A.G. How to make C-N bonds using boronic acids and their derivatives without transition metals. Chem. Soc. Rev. 2020, 49, 5159–5177. [Google Scholar] [CrossRef] [PubMed]
  15. Rahman, M.M.; Buchspies, J.; Szostak, M. N-Acylphthalimides: Efficient acyl coupling reagents in Suzuki-Miyaura cross-coupling by N-C cleavage catalyzed by Pd-PEPPSI precatalysts. Catalysts 2019, 9, 129. [Google Scholar] [CrossRef] [Green Version]
  16. Buchspies, J.; Rahman, M.M.; Szostak, M. Suzuki-Miyaura cross-coupling of amides using well-defined, air- and moisture-stable nickel/NHC (NHC = N-heterocyclic carbene) complexes. Catalysts 2020, 10, 372. [Google Scholar] [CrossRef] [Green Version]
  17. Lei, P.; Meng, G.; Szostak, M. General method for the Suzuki-Miyaura cross-coupling of amides using commercially available, air- and moisture-stable palladium/NHC (NHC = N-heterocyclic carbene) complexes. ACS Catal. 2017, 7, 1960–1965. [Google Scholar] [CrossRef]
  18. Liu, C.; Li, G.; Shi, S.; Meng, G.; Lalancette, R.; Szostak, R.; Szostak, M. Acyl and Decarbonylative Suzuki coupling of N-acetyl amides: Electronic tuning of twisted, acyclic amides in catalytic carbon−nitrogen bond cleavage. ACS Catal. 2018, 8, 9131–9139. [Google Scholar] [CrossRef]
  19. Osumi, Y.; Liu, C.; Szostak, M. N-Acylsuccinimides: Twist-controlled, acyl-transfer reagents in Suzuki-Miyaura cross-coupling by N-C amide bond activation. Org. Biomol. Chem. 2017, 15, 8867–8871. [Google Scholar] [CrossRef]
  20. Szostak, M.; Meng, G.; Shi, S. Palladium-catalyzed Suzuki−Miyaura cross-coupling of amides via site-selective N−C bond cleavage by cooperative catalysis. ACS Catal. 2016, 6, 7335–7339. [Google Scholar]
  21. Meng, G.; Szostak, R.; Szostak, M. Suzuki−Miyaura cross-coupling of N-acylpyrroles and pyrazoles: Planar, electronically activated amides in catalytic N-C cleavage. Org. Lett. 2017, 19, 3596–3599. [Google Scholar] [CrossRef] [PubMed]
  22. Racine, E.; Monnier, F.; Vors, J.-P.; Taillefer, M. Direct N-cyclopropylation of secondary acyclic amides promoted by copper. Chem. Commun. 2013, 49, 7412–7414. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  23. Rossi, S.A.; Shimkin, K.W.; Xu, Q.; Mori-Quiroz, L.M.; Watson, D.A. Selective formation of secondary amides via the copper-catalyzed cross-coupling of alkylboronic acids with primary amides. Org. Lett. 2013, 15, 2314–2317. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  24. Roy, S.; Sarma, M.J.; Kashyap, B.; Phukan, P. A quick Chan-Lam C-N and C-S cross coupling at room temperature in the presence of square pyramidal [Cu(DMAP)4I]I as a catalyst. Chem. Commun. 2016, 52, 1170–1173. [Google Scholar] [CrossRef]
  25. Munir, I.; Zahoor, A.F.; Rasool, N.; Naqvi, S.A.R.; Zia, K.M.; Ahmad, R. Synthetic applications and methodology development of Chan-Lam coupling: A review. Mol. Divers. 2019, 23, 215–259. [Google Scholar] [CrossRef]
  26. Zhang, Z.; Yu, Y.; Liebeskind, L.S. N-amidation by copper-mediated cross-coupling of organostannanes or boronic acids with O-acetyl hydroxamic Acids. Org. Lett. 2008, 10, 3005–3008. [Google Scholar] [CrossRef] [Green Version]
  27. Broumidis, E.; Jones, M.C.; Vilela, F.; Lloyd, G.O. Mechanochemical synthesis of N-aryl amides from O-protected hydroxamic acids. ChemPlusChem 2020, 85, 1754–1761. [Google Scholar] [CrossRef]
  28. Li, J.H.; Wang, Y.; Xie, H.L.; Ren, S.F.; Liu, J.-B.; Luo, N.H.; Qiu, G.Y.S. Iron-catalyzed cross-coupling of N-methoxy amides and arylboronic acids for the synthesis of N-aryl amides. Mol. Catal. 2021, 516, 111993. [Google Scholar] [CrossRef]
  29. Lai, X.J.; Liu, J.-B.; Wang, Y.C.; Qiu, G.Y.S. Iron-catalyzed intramolecular acyl nitrene/alkyne metalation for the synthesis of pyrrolo[2,1-a]isoindol-5-ones. Chem. Commun. 2021, 57, 2077–2080. [Google Scholar] [CrossRef]
  30. Liu, J.-B.; Ren, M.F.; Lai, X.J.; Qiu, G.Y.S. Iron-catalyzed stereoselective haloamidation of amide-tethered alkynes. Chem. Commun. 2021, 57, 4259–4262. [Google Scholar] [CrossRef]
  31. Zhong, P.Y.; Wu, J.J.; Wu, J.R.; Liu, K.M.; Wang, C.F.; Liu, J.-B. Solvent-controlled selective synthesis of amides and thioureas from isothiocyanates. Tetrahedron Lett. 2022, 107, 154099. [Google Scholar] [CrossRef]
  32. Chen, Z.H.; Hu, L.A.; Zeng, F.Y.; Zhu, R.R.; Yu, Q.Z.; Huang, J.H. Selective mono-alkylation of N-methoxybenzamides. Chem. Commun. 2017, 53, 4258–4261. [Google Scholar] [CrossRef]
  33. Rao, W.-H.; Jiang, L.-L.; Zhao, J.-X.; Jiang, X.; Zou, G.-D.; Zhou, Y.-Q.; Tang, L. Selective O-cyclization of N-methoxy aryl amides with CH2Br2 or 1,2-DCE via palladium-catalyzed C-H activation. Org. Lett. 2018, 20, 6198–6201. [Google Scholar] [CrossRef]
  34. Deng, X.M.; Wang, Y.; Liu, J.-B.; Wan, C.F.; Luo, N.H. Synthesis of N-methoxy-1 phosphoryloxy imidates through a copper-catalyzed cross-dehydrogenative coupling of N-methoxylamides with phosphites. Tetrahedron Lett. 2022, 105, 154049. [Google Scholar] [CrossRef]
  35. Collman, J.P.; Zhong, M.; Zhang, C.; Costanzo, S. Catalytic activities of Cu(II) complexes with nitrogen-chelating bidentate ligands in the coupling of imidazoles with arylboronic acids. J. Org. Chem. 2001, 66, 7892. [Google Scholar] [CrossRef]
  36. Wang, R.X.; Xie, H.L.; Lai, X.J.; Liu, J.-B.; Li, J.H.; Qiu, G.Y.S. Visible light-enabled iron-catalyzed selenocyclization of N-methoxy-2-alkynylbenzamide. Mol. Catal. 2021, 515, 111881. [Google Scholar] [CrossRef]
  37. Ren, M.F.; Yan, X.Y.; Lai, X.J.; Liu, J.-B.; Zhou, H.W.; Qiu, G.Y.S. Nitrenium ion-based ipso-addition and ortho-cyclization of arenes under photo and iron dual-catalysis. Mol. Catal. 2022, 528, 112413. [Google Scholar] [CrossRef]
Catalysts 12 01278 sch001 550
Scheme 1. (a) Pd or Ni catalyzed C-arylation; (b) Cu catalyzed N-arylation; (c) Fe catalyzed N-arylation; (d) Cu catalyzed O-arylation (this work).
Scheme 1. (a) Pd or Ni catalyzed C-arylation; (b) Cu catalyzed N-arylation; (c) Fe catalyzed N-arylation; (d) Cu catalyzed O-arylation (this work).
Catalysts 12 01278 sch001
Catalysts 12 01278 sch002 550
Scheme 2. Boronic acid scope in copper-catalyzed C-O coupling of N-methoxy amides a,b. a Reaction conditions: 1 (0.2 mmol), 2 (1.5 equiv.), CuI (0.2 equiv.), Na3PO4·12H2O (2 equiv.), DCE (2.0 mL), air, 130 ℃, 24 h. b Isolated yield based on 1a. ND = Not Detected.
Scheme 2. Boronic acid scope in copper-catalyzed C-O coupling of N-methoxy amides a,b. a Reaction conditions: 1 (0.2 mmol), 2 (1.5 equiv.), CuI (0.2 equiv.), Na3PO4·12H2O (2 equiv.), DCE (2.0 mL), air, 130 ℃, 24 h. b Isolated yield based on 1a. ND = Not Detected.
Catalysts 12 01278 sch002
Catalysts 12 01278 sch003 550
Scheme 3. N-methoxy amides scope in copper-catalyzed C-O cross-coupling b,c. a The boronic acid component is p-tolylboronic acid. b Reaction conditions: 1 (0.2 mmol), 2 (1.5 equiv.), CuI (0.2 equiv.), Na3PO4·12H2O (2 equiv.), DCE (2.0 mL), air, 130 °C, 24 h. c Isolated yield based on 1a. ND = Not Detected.
Scheme 3. N-methoxy amides scope in copper-catalyzed C-O cross-coupling b,c. a The boronic acid component is p-tolylboronic acid. b Reaction conditions: 1 (0.2 mmol), 2 (1.5 equiv.), CuI (0.2 equiv.), Na3PO4·12H2O (2 equiv.), DCE (2.0 mL), air, 130 °C, 24 h. c Isolated yield based on 1a. ND = Not Detected.
Catalysts 12 01278 sch003
Catalysts 12 01278 sch004 550
Scheme 4. Control experiments of the copper-catalyzed C-O coupling reaction.
Scheme 4. Control experiments of the copper-catalyzed C-O coupling reaction.
Catalysts 12 01278 sch004
Catalysts 12 01278 g001 550
Figure 1. Plausible mechanism of the copper-catalyzed C-O coupling reaction.
Figure 1. Plausible mechanism of the copper-catalyzed C-O coupling reaction.
Catalysts 12 01278 g001
Table
Table 1. Optimization of the reaction conditions a.
Table 1. Optimization of the reaction conditions a.
Catalysts 12 01278 i001
Entry[Cu]Base (equiv)Solv.Temp.
(°C)		Yield of
3a b (%)		Yield of
4a b (%)
1Cu(OAc)2·H2OK2CO3DCE80286
2Cu(OAc)2·H2O-DCERT˂59
3Cu(OAc)2·H2OK2CO3DCERT3019
4Cu(OAc)2·H2OEt3NDCERT˂512
5Cu(OAc)2·H2OKOHDCERT1811
6Cu(OAc)2·H2OCs2CO3DCERT1930
7Cu(OAc)2·H2Ot-BuOKDCERT1133
8Cu(OAc)2·H2ONa2CO3DCERT831
9Cu(OAc)2·H2ONa3PO4·12H2ODCERT3429
10Cu(OAc)2·H2ONa3PO4·12H2OTHFRT00
11Cu(OAc)2·H2ONa3PO4·12H2OacetoneRT˂5˂5
12Cu(OAc)2·H2ONa3PO4·12H2OEART22˂5
13Cu(OAc)2·H2ONa3PO4·12H2OEtOHRT0˂5
14Cu(OAc)2·H2ONa3PO4·12H2OTolueneRT3225
15Cu(OAc)2·H2ONa3PO4·12H2ODMFRT00
16Cu(OAc)2·H2ONa3PO4·12H2O1,4-dioxaneRT00
17Cu(OAc)2·H2ONa3PO4·12H2ODMSORT00
18Cu(OAc)2·H2ONa3PO4·12H2OEt2ORT319
19Cu(OAc)2·H2ONa3PO4·12H2OMeCNRT˂5˂5
20Cu(OAc)2·H2ONa3PO4·12H2ODCE4018˂5
21Cu(OAc)2·H2ONa3PO4·12H2ODCE8028˂5
22Cu(OAc)2·H2ONa3PO4·12H2ODCE12041˂5
23Cu(OAc)2·H2ONa3PO4·12H2ODCE13048˂5
24Cu(OAc)2·H2ONa3PO4·12H2ODCE140300
25CuINa3PO4·12H2ODCE130700
26CuCl2Na3PO4·12H2ODCE1303816
27CuBrNa3PO4·12H2ODCE130370
a Reaction conditions: 1a (0.2 mmol), 2a (0.3 mmol), catalyst (0.2 equiv), base (0.4 mmol), solvent (2.0 mL), air, 24 h. b Isolated yield based on 1a.
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Wang, Y.; Xie, H.; Liu, K.; Li, J.; Liu, J.-B. Selective C-O Coupling Reaction of N-Methoxy Arylamides and Arylboronic Acids Catalyzed by Copper Salt. Catalysts 2022, 12, 1278. https://doi.org/10.3390/catal12101278

AMA Style

Wang Y, Xie H, Liu K, Li J, Liu J-B. Selective C-O Coupling Reaction of N-Methoxy Arylamides and Arylboronic Acids Catalyzed by Copper Salt. Catalysts. 2022; 12(10):1278. https://doi.org/10.3390/catal12101278

Chicago/Turabian Style

Wang, Ying, Huilin Xie, Kunming Liu, Jinhui Li, and Jin-Biao Liu. 2022. "Selective C-O Coupling Reaction of N-Methoxy Arylamides and Arylboronic Acids Catalyzed by Copper Salt" Catalysts 12, no. 10: 1278. https://doi.org/10.3390/catal12101278

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