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Synthesis of novel 7-(heteryl/aryl)chromones via Suzuki coupling reaction

  • Naredla Anitha , K. Venugopal Reddy EMAIL logo and Y. Jayaprakash Rao
Published/Copyright: March 31, 2014
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Heterocyclic Communications
From the journal Heterocyclic Communications Volume 20 Issue 2

Abstract

A series of new 7-heteroaryl and arylchromones 6a–l were synthesized in moderate to good yields by the Suzuki reaction of the triflate (pseudo halide) 5 and a variety of heteroaryl and aryl boronic acids. The resulting products may be used as precursors for synthesis of potentially relevant compounds. The structures of all synthesized compounds were established based on IR, 1H NMR, 13C NMR, and DIPMS.

Keywords: heteroaryl/arylboronic acids; heteroaryl/arylchromones; pseudo halides; Suzuki coupling

Introduction

Chromones (4H-1-benzopyran-4-ones) are naturally occurring oxygen-containing heterocyclic compounds, which perform important biological functions in nature [1] and are a recognized pharmacophore of a large number of bioactive molecules of either natural or synthetic origin. Their derivatives are antibacterial, anticancer, antioxidant, estrogenic agents [2–4], and have been considered as privileged structures in drug development [5]. The Suzuki coupling reaction is the palladium catalyzed C-C bond formation reaction of organoboran compounds with organic halides or pseudo halides [6]. The Suzuki reaction has recently gained much prominence because it is suitable for large-scale synthesis including the industrial synthesis of pharmaceuticals and fine chemicals [7–9]. The key advantages of Suzuki coupling are mild reaction conditions and commercial availability of a wide variety of heterocyclic and arylboronic acids that are safer than other organometallic reagents [10–14]. The Suzuki coupling process tolerates many functional groups present in substrates [15], and it proceeds well in the presence of water. In addition, the inorganic byproduct of the reaction is non-toxic and easily removed from the mixture. This report presents synthesis of 7-heteryl/aryl-2,3-dimethylchromones starting from 7-hydroxy-2,3-dimethylchromones using the Suzuki coupling reaction. To the best of our knowledge, there are no reports in the literature on C-C bond formation at C-7 position of chromones.

Results and discussion

The aim of the present work was to develop a simple and efficient procedure for the preparation of new chromone derivatives bearing substituted heteroaryl and aryl moieties by Suzuki cross coupling reactions. Aryl triflates are good leaving groups that are more reactive than aryl chlorides, bromides, and more stable to moisture and air. The key intermediate chromenyl triflate 5 was prepared by a conventional method, which involves treatment of the corresponding 7-hydroxy-2,3-dimethylchromone 4 with triflic anhydride in the presence of base triethylamine [16, 17]. Compound 4 [18, 19] was prepared from resorcinol according to a procedure in the literature (Scheme 1). The structure of chromenyl triflate 5 was established by spectral analysis. The reaction of the substrate 5 with boronic acids and esters in the presence of Pd(PPh3)4, sodium carbonate in N,N-dimethylformamide under mild conditions afforded the corresponding heteroaryl and arylchromones 6a–l in moderate to good yields (Scheme 2). Because aryl triflates are sensitive to strong bases, sodium carbonate was used to carry out the Suzuki reaction. The structures of compounds 6a–l were confirmed by spectral analysis.

Scheme 1 Synthesis of 2,3-dimethyl-4-oxo-4H-chromen-7-yl trifluoromethanesulfonate (5).
Scheme 1

Synthesis of 2,3-dimethyl-4-oxo-4H-chromen-7-yl trifluoromethanesulfonate (5).

Scheme 2 Synthesis of 7-(aryl/heteryl)-substituted chromones 6a–l.
Scheme 2

Synthesis of 7-(aryl/heteryl)-substituted chromones 6a–l.

Conclusions

A simple and efficient method of synthesis of heteryl- and aryl-substituted chromones 6a–l using the Suzuki cross coupling reaction was described.

Experimental

Chromenyl triflate 5 [16, 17] and 7-hydroxy-2,3-dimethylchromone 4 [18, 19] were prepared by the reported procedures. Melting points were obtained on a Polmon instrument, model MP 96, and were uncorrected. IR spectra were recorded in KBr pellets on a Fourier transform Perkin-Elmer model 337 instrument. 1H NMR (400 MHz) and 13C NMR (100.6 MHz) spectra were recorded in CDCl3 solution on a Bruker 400 spectrometer using TMS as an internal standard. Mass spectral data were obtained with an Agilent-6310 ion trap mass spectrometer.

General procedure for synthesis of 7-(aryl and heteroaryl)-2,3-dimethyl-4-chromones 6a–l

A mixture of chromenyl triflate 5 (0.8 mmol), a boronic acid (1.2 mmol), and aqueous Na2CO3 (1 mL, 2 m) in DMF was purged with nitrogen with stirring for 30 min, and then treated with 4 mol% of tetrakis(triphenylphosphine)palladium(0). The reaction mixture was stirred at 60°C for 3–4 h. After completion of the reaction, the mixture was cooled to room temperature, diluted with water (50 mL), and extracted with diethyl ether (3 × 30 mL). The extract was dried over Na2SO4 and concentrated under reduced pressure to give crude compounds 6a–l, which were purified by column chromatography on silica gel.

2,3-Dimethyl-7-(5-methyl-2-furyl)-4H-4-chromone (6a)

Yield 60%; white solid; mp 123°C; IR: 1633.0 cm-1 (C=O); 1H NMR: δ 8.14 (d, J = 8.3 Hz, H-5), 7.60 (m, H-6, H-8), 6.71 (d, J = 3.0 Hz, H-3′), 6.10 (d, J = 3.0 Hz, H-4′), 2.40 (s, CH3-2), 2.39 (s, CH3-5′), 2.05 (s, CH3-3); 13C NMR: δ 177.6 (C=O), 166.9 (C-2′), 161.8 (C-2), 156.4 (C-8a), 156.2 (C-5′), 142.4 (C-7), 128.4 (C-4′), 124.8 (C-3′), 124.4 (C-4a), 123.5 (C-5), 121.4 (C-6), 116.7 (C-3), 115.1 (C-8), 20.2 (5′-CH3), 18.7 (2-CH3), 10.2 (3-CH3). HR-ESI-MS. Calcd for C16H14O3+: m/z 254.0943, found: m/z 254.0938.

7-(2,3-Diflurophenyl)-2,3-dimethyl-4H-4-chromone (6b)

Yield 70%; mp 136°C; IR: 1638.0 cm-1 (C=O); 1H NMR: δ 8.28 (d, J = 8.0 Hz, H-5), 7.61 (d, J = 1.2 Hz, H-8), 7.54 (dd, J = 8.0 Hz, J = 1.2 Hz, H-6), 7.29–7.20 (m, H-3′, H-4′, H-5′), 2.46 (s, CH3-2), 2.11 (s, CH3-3); 13C NMR: δ 177.4 (C=O), 162.2 (C-2), 155.6 (C-8a), 148.2 (C-2′), 142.7 (C-3′), 143.6 (C-5), 136.7 (C-7), 129.6 (C-1′), 127.3 (C-6′), 126.7 (C-5′), 123.3 (C-4a), 121.7 (C-4′), 117.3 (C-6), 117.1 (C-3), 115.4 (C-8), 18.6 (2-CH3), 10.1 (3-CH3). HR-ESI-MS: Calcd for C17H12F2O2+: m/z 286.0805, found: m/z 286.0801.

7-(3-Fluorophenyl)-2,3-dimethyl-4H-4-chromone (6c)

Yield 58%; mp 107°C; IR: 1630.0 cm-1 (C=O); 1H NMR: δ 8.25 (d, J = 8.0 Hz, H-5), 7.60 (d, J = 1.2 Hz, H-8), 7.56–7.49 (m, H-6, H-2′), 7.43–7.37 (m, H-5′), 7.28–7.23 (m, H-4′, H-6′), 2.45 (s, CH3-2), 2.10 (s, CH3-3); 13C NMR: δ 176.1 (C=O), 161.5 (C-2), 155.5 (C-8a), 148.2 (C-3′), 142.7 (C-1′), 144.8 (C-5), 134.9 (C-7), 129.6 (C-2′), 127.3 (C-6′), 126.7 (C-5′), 123.4 (C-4a), 122.6 (C-4′), 118.1 (C-6), 117.4 (C-3), 115.6 (C-8), 18.6 (2-CH3), 10.1 (3-CH3). HR-ESI-MS. Calcd for C17H12FO2+: m/z 268.0900, found: m/z 268.0903.

7-(3,4-Dimethylphenyl)-2,3-dimethyl-4H-4-chromone (6d)

Yield 62%; mp 89°C; IR: 1628.0 cm-1 (C=O); 1H NMR: δ 8.21 (d, J = 8.0 Hz, H-5), 7.58 (d, J = 1.6 Hz, H-8), 7.56 (s, H-2′), 7.43–7.38 (m, H-6′, H-5′, H-4′), 7.24 (d, J = 8.0 Hz, H-6), 2.43 (s, CH3-2), 2.35 (s, CH3-1′), 2.32 (s, CH3-2′), 2.07 (s, CH3-3); 13C NMR: δ 177.8 (C=O), 161.8 (C-2), 156.2 (C-8a), 146.1 (C-3′), 137.3 (C-4′), 137.2 (C-7), 136.9 (C-1′), 130.3 (C-2′), 128.5 (C-5′), 126.2 (C-6′), 124.7 (C-4a), 123.5 (C-5), 121.1 (C-6), 116.9 (C-3), 115.2 (C-8), 19.9 (4′-CH3), 19.5 (3′-CH3), 18.6 (2-CH3), 10.1 (3-CH3). HR-ESI-MS. Calcd for C19H18O2+: m/z 278.1307, found: m/z 278.1301.

2,3-Dimethyl-7-(2-thienyl)-4H-4-chromone (6e)

Yield 56%; mp 112°C; IR: 1635.0 cm-1 (C=O); 1H NMR: δ 8.15 (d, J = 8.0 Hz, H-5), 7.58–7.55 (m, H-6, H-8), 7.43 (d, J = 3.0 Hz, H-3′), 7.37 (dd, J = 3.0 Hz, J = 3.6 Hz, H-4′), 7.11 (d, J = 3.6 Hz, H-5′), 2.40 (s, CH3-2), 2.05 (s, CH3-3); 13C NMR: δ 177.4 (C=O), 161.9 (C-2), 156.2 (C-8a), 142.4 (C-7), 138.9 (C-2′), 128.4 (C-4′), 126.7 (C-5′), 126.5 (C-5′), 124.9 (C-3′), 124.7 (C-4a), 123.5 (C-5), 121.1 (C-6), 116.9 (C-3), 115.2 (C-8), 18.6 (2-CH3), 10.1 (3-CH3). HR-ESI-MS. Calcd for C15H12O2S+: m/z 256.0558, found: m/z 256.0547.

2,3-Dimethyl-7-(4-chloro-3-pyridyl)-4H-4-chromone (6f)

Yield 64%; mp 145°C; IR: 1632.0 cm-1 (C=O); 1H NMR: δ 8.66 (s, H-6′), 8.28 (d, J = 8.4 Hz, H-5), 7.90 (dd, J = 8.4 Hz, J = 2.8 Hz, H-4′), 7.56 (d, J = 1.6 Hz, H-8), 7.52 (dd, J = 8.4 Hz, J = 1.6 Hz, H-6), 7.45 (d, J = 8.4 Hz, H-3′), 2.44 (s, CH3-2), 2.08 (s, CH3-3); 13C NMR: δ 177.4 (C=O), 162.2 (C-2), 156.1 (C-8a), 151.5 (C-2′) 148.1 (C-6′), 141.1 (C-5′), 137.3 (C-7), 134.0 (C-4′), 127.0 (C-6), 124.5 (C-4a), 123.2 (C-5), 122.1 (C-3′), 117.4 (C-3), 115.8 (C-8), 18.6 (2-CH3), 10.1 (3-CH3). HR-ESI-MS. Calcd for C16H1235ClNO2+: m/z 285.0557, found: m/z 285.0548.

2,3-Dimethyl-7-(2-methoxyphenyl)-4H-4-chromone (6g)

Yield 60%; mp 92°C; IR: 1634.0 cm-1 (C=O); 1H NMR: δ 8.19 (dd, J = 8.2 Hz, J = 0.3 Hz, H-6), 7.57 (d, J = 0.3 Hz, H-8), 7.51 (dd, J = 8.1 Hz, J = 1.7 Hz, H-6′), 7.38 (m, H-4′, H-3′), 7.05 (m, H-5′, H-5), 3.84 (s, OCH3), 2.43 (s, CH3-2), 2.08 (s, CH3-3). 13C NMR: δ 177.9 (C=O), 161.9 (C-2), 156.5 (C-2′), 155.7 (C-8a), 143.6 (C-7), 130.8 (C-6′), 129.7 (C-1′), 128.9 (C-4′), 126.2 (C-5), 125.2 (C-4a), 121.1 (C-6), 121.0 (C-5′), 118.2 (C-3), 116.9 (C-8), 111.4 (C-3′), 55.6 (OCH3), 18.6 (2-CH3), 10.1 (3-CH3). HR-ESI-MS. Calcd for C18H16O3+: m/z 280.1099, found: m/z 280.1088.

7-(4-Fluro-3-methoxyphenyl)-2,3-dimethyl-4H-4-chromone (6h)

Yield 71%; mp 118°C; IR: 1625.0 cm-1 (C=O); 1H NMR: δ 8.23 (d, J = 8.2 Hz, H-6), 7.53 (m, H-8, H-5), 7.19 (m, H-2′, H-5′, H-6′), 3.98 (s, OCH3), 2.44 (s, CH3-2), 2.08 (s, CH3-3); 13C NMR: δ 177.1 (C=O), 162.0 (C-2), 156.1 (C-8a), 151.6 (C-3′), 148.0 (C-4′), 145.2 (C-1′), 136.1 (C-7), 126.4 (C-5), 123.5 (C-6), 121.4 (C-6′), 120.0 (C-5′), 117.1 (C-4a), 116.4 (C-2′), 115.5 (C-3), 112.6 (C-8), 56.4 (OCH3), 18.6 (2-CH3), 10.1 (3-CH3). HR-ESI-MS. Calcd for C18H15FO3+: m/z 298.1005, found: m/z 298.1001.

7-(3-Cyanophenyl)-2,3-dimethyl-4H-4-chromone (6i)

Yield 76%; mp 96°C; IR: 1635.0 cm-1 (C=O); 2212.0 cm-1 (CN); 1H NMR: δ 8.28 (d, J = 8.2 Hz, H-6), 7.93 (d, J = 1.4 Hz, H-8), 7.87 (dd, J = 7.4 Hz, J = 1.3 Hz, H-4′), 7.71 (dd, J = 7.4 Hz, J = 7.6 Hz, H-5′), 7.58 (m, H-5, H-2′, H-6′), 2.45 (s, CH3-2), 2.09 (s, CH3-3); 13C NMR: δ 177.5 (C=O), 162.2 (C-2), 156.1 (C-8a), 143.4 (C-7), 140.7 (C-1′), 131.8 (C-4′), 131.6 (C-2′), 130.9 (C-6′), 129.9 (C-5′), 126.9 (C-4a), 123.3 (C-5), 122.1 (C-6), 118.1 (CN), 117.4 (C-3), 116.0 (C-8), 113.3 (C-3′), 18.6 (2-CH3), 10.1 (3-CH3). HR-ESI-MS. Calcd for C18H13NO2+: m/z 275.0946, found: m/z 275.0937.

7-(2-Trifluromethylphenyl)-2,3-dimethyl-4H-4-chromone (6j)

Yield 70%; mp 128°C; IR: 1630.0 cm-1 (C=O); 1H NMR: δ 8.21 (dd, J = 8.1 Hz, J = 0.2 Hz, H-6′), 7.78 (d, J = 7.8 Hz, H-5), 7.90 (dd, J = 8.4 Hz, J = 2.8 Hz, H-4′), 7.56 (d, J = 1.6 Hz, H-8), 7.52 (dd, J = 8.4 Hz, J = 1.6 Hz, H-6), 7.45 (d, J = 8.4 Hz, H-3′), 2.44 (s, CH3-2), 2.08 (s, CH3-3); 13C NMR: δ 177.5 (C=O), 162.2 (C-2), 156.1 (C-8a), 143.4 (C-1′), 140.7 (C-7), 134.4 (C-2′), 130.6 (C-5′), 129.7 (C-6′), 127.4 (C-3′), 126.7 (C-4a), 123.3 (C-5), 122.1 (C-6), 118.1 (CF3), 117.4 (C-3), 116.2 (C-8), 113.4 (C-3′), 18.4 (2-CH3), 10.1 (3-CH3). HR-ESI-MS. Calcd for C18H13F3O2+: m/z 318.0869, found: m/z 318.0864.

7-(3-Chloro-4-methylphenyl)-2,3-dimethyl-4H-4-chromone (6k)

Yield 70%; mp 136°C; IR: 1632.0 cm-1 (C=O); 1H NMR: δ 8.22 (dd, J = 8.2 Hz, J = 1.4 Hz, H-6), 7.46 (d, J = 1.4 Hz, H-8), 7.40 (d, J = 7.8 Hz, H-5′), 7.33 (d, J = 7.8 Hz, H-6′), 7.46 (d, J = 8.2 Hz, H-5), 7.15 (s, H-2′), 2.43 (s, CH3-2), 2.39 (s, CH3), 2.08 (s, CH3-3); 13C NMR: δ 177.1 (C=O), 162.0 (C-2), 155.5 (C-8a), 144.2 (C-1′), 139.8 (C-7), 135.9 (C-4′), 131.9 (C-3′), 130.9 (C-2′), 130.6 (C-5′), 127.9 (C-6′), 126.1 (C-4a), 125.5 (C-5), 121.5 (C-6), 118.4 (C-3), 117.1 (C-8), 20.9 (4′-CH3), 18.6 (2-CH3), 10.1 (3-CH3). HR-ESI-MS. Calcd for C18H1535ClO2+: m/z 298.0761, found: m/z 298.0765.

7-(3-Chloro-4-fluoro-phenyl)-2,3-dimethyl-4H-4-chromone (6l)

Yield 67%; mp 140°C; IR: 1627.0 cm-1 (C=O); 1H NMR: δ 8.24 (dd, J = 8.2 Hz, J = 1.4 Hz, H-6), 7.68 (d, J = 1.4 Hz, H-8), 7.52 (m, H-2′, H-5′, H-6′), 7.25 (d, J = 8.2 Hz, H-5), 2.44 (s, CH3-2), 2.08 (s, CH3-3); 13C NMR: δ 177.6 (C=O), 162.1 (C-2), 159.6 (C-8a), 157.1 (C-7), 156.1 (C-1′), 143.6 (C-5), 136.7 (C-6′), 129.6 (C-2′), 127.1 (C-3′), 126.7 (C-5′), 123.3 (C-4a), 121.7 (C-4′), 117.3 (C-6), 117.0 (C-4a), 115.6 (C-8), 18.6 (2-CH3), 10.1 (3-CH3). HR-ESI-MS. Calcd for C17H12F35ClO2+: m/z 302.0510, found: m/z 302.0506.

Corresponding author: K. Venugopal Reddy, Department of Chemistry, Osmania University, Hyderabad 500007, Andhra Pradesh, India, e-mail:

Acknowledgments

The authors are grateful to Dr. Reddy’s Laboratories Ltd. for providing facilities and analytical support.

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Received: 2013-12-29
Accepted: 2014-2-4
Published Online: 2014-3-31
Published in Print: 2014-4-1

©2014 by Walter de Gruyter Berlin/Boston

This article is distributed under the terms of the Creative Commons Attribution Non-Commercial License, which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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https://doi.org/10.1515/hc-2014-0004
Keywords for this article
heteroaryl/arylboronic acids; heteroaryl/arylchromones; pseudo halides; Suzuki coupling
Creative Commons
BY-NC-ND 3.0

Articles in the same Issue

  1. Frontmatter
  2. Review
  3. Chemical constituents of plants from the genus Neolitsea
  4. Preliminary Communication
  5. One-pot two-step synthesis of 2,5-dihydro-2-oxofuran-3-carboxamides
  6. Research Articles
  7. Synthesis of new 2- and 3-hydroxyquinoline-4-carboxylic acid derivatives as potential antioxidants
  8. Reactions of nitroxides XIV. Analogs of phenoxy carboxylic herbicides based on the piperidine scaffold; unexpected fungicidal activity of the 2-[(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)oxy]butanoic acid
  9. A simple approach to fused pyrido[2,3-d]pyrimidines incorporating khellinone and trimethoxyphenyl moieties as new scaffolds for antibacterial and antifungal agents
  10. Synthesis and molecular docking of indole and carbazole derivatives with potential pharmacological activity
  11. An access to new N-pyrrolylcarboxylic acids as potential COX-2 inhibitors via Paal-Knorr cyclization
  12. Structural modification of isoalantolactone and biological activity against the hepatoma cell lines
  13. Three-component anti selective Mannich reactions in a tetrahydro-4-pyranone system by using PDAG-Co catalyst
  14. Synthesis of novel 7-(heteryl/aryl)chromones via Suzuki coupling reaction
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