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Supporting Information

One pot direct synthesis of β-ketoesters via

carbonylation of aryl halides using cobalt

carbonylPoongavanam Baburajan and Kuppanagounder P. Elango*

Department of Chemistry, Gandhigram Rural Institute (Deemed University),

Gandhigram 624302, India E-mail: drkpelango@rediffmail.com

CONTENTS

1. General information

2. General procedure

3. Preparations and characterization of the products

4. 1H NMR and 13C NMR spectral data of 3a to 3w

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1. General information

Commercially available reagents were used as received in this work. The solvents were freshly distilled and used. All the reactions were executed with a Biotage Initiator. SW version: 2.2 build 5743 instrument. Biotage high precision microwave vials and magnetic pellets are used for the reactions. Purification of products was performed by silica gel column chromatography. 1H NMR spectra were obtained using a 400 MHz or 300 MHz spectrometer. 13C NMR spectra were obtained from a 100 MHz spectrometer or 75 MHz. All 1H and 13C NMR experiments are reported in parts per million (ppm) downfield from tetramethylsilane and were measured relative to the signals for residual chloroform in the deuterated solvents. The mass spectra were recorded on an Ultra Performance Liquid Chromatography (UPLC) or Liquid chromatography-mass spectrometry (LC-MS). All the spectral data matched with the literature descriptions.

2. General procedure

To a stirred mixture of aryl or heteroaryl halide (Br, I) (0.5 mmol), potassium mono ethyl malonate (0.75 mmol) in THF (10 mL) taken in a 30 mL microwave vial, was added Pd(OAc)2 (5 mol%), Xantphos (5 mol %), MgCl2 (0.75), Et3N ( 0.75 mmol), imidazole (1 mmol) followed by Co2(CO)8 (0.15 mmol). The vial was sealed immediately and microwave irradiated at 90 °C for 30 min. The reaction mixture was concentrated and diluted with ethyl acetate and water. The ethyl acetate layer was separated, dried over sodium sulphate and concentrated. The crude product obtained was purified by column chromatography to get the pure compound.

3. Preparations and characterization of the products

3a. 3-Oxo-3-p-tolyl-propionic acid ethyl ester

The general procedure was followed by using 0.5 mmol of 1-bromo-4-methyl-benzene or 1-iodo-4-methyl-benzene and Co2(CO)8 (52 mg, 0.15 mmol). Purification by flash chromatography using 0 to 5% of ethyl acetate in hexane gave the title compound 3a as a colourless liquid. Yield: 91 mg, 89% (X= Br) & 79 mg, 77 % (X= I). LCMS: (M+H)+ 207.3; 1H-NMR (400 MHz, CDCl3): (keto:enol form) δ 1.26 (t, J = 7.20 Hz, 3H), 2.43 (s, 3H), 3.97 (s, 2H), 4.22 (q, J = 7.20 Hz, 2H), 7.28 (d, J = 8.00 Hz, 2H), 7.85 (d, J = 8.40 Hz, 2H); 13C-NMR (75MHz, CDCl3, δ ppm): 14.1, 21.7, 45.9, 61.4, 126.0, 128.6, 129.4, 133.6, 144.7, 167.7, 192.1.

3b.3-Oxo-3-phenyl-propionic acid ethyl ester

The general procedure was followed by using 0.5 mmol of bromobenzene or iodobenzene. Purification by flash chromatography using 0 to 5% of ethyl acetate in hexane gave the title compound 3b as a colourless liquid. Yield: 81 mg, 85% (X= Br) & 78 mg, 82% (X= I); LCMS: (M+H)+ 193.3; 1H-NMR (400 MHz, CDCl3): (Keto:Enol form) δ 1.26 (t, J = 7.16 Hz, 3H), 1.34 (t, J = 7.16 Hz, 1.4H), 4.00 (s, 2H), 4.22 (q, J = 7.12 Hz, 2H), 4.26 (q, J = 7.08 Hz, 0.92H), 5.68 (s, 0.46H), 7.49-7.51 (m, 2H), 7.58-7.59 (m, 1H), 7.96-7.97 (m, 2H), 12.59

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(s, 0.46H); 13C-NMR (75MHz, CDCl3, δ ppm): 14.1, 46.0, 60.3, 61.5, 87.4, 126.0, 128.5, 131.2, 133.7, 136.0, 167.5, 192.5.

3c. 3-(4-Methoxy-phenyl)-3-oxo-propionic acid ethyl ester

The general procedure was followed by using 0.5 mmol of 1-bromo-4-methoxy-benzene or 1-iodo-4-methoxy-benzene. Purification by flash chromatography using 0 to 5% of ethyl acetate in hexane gave the title compound 3c as a colourless liquid. Yield: 102 mg, 92% (X= Br) & 98 mg, 89% (X= I); LCMS: (M+H)+ 223.5; 1H-NMR (300 MHz, CDCl3): (Keto:Enol form) δ 1.26 (t, J = 9.52 Hz, 3H), 3.87 (s, 3H), 3.95 (s, 2H), 4.22 (q, J = 9.52 Hz, 2H), 6.95 (m, 2H), 7.92 (m, 2H); 13C-NMR (75MHz, CDCl3, δ ppm): 14.2, 45.7, 55.4, 61.3, 113.8, 130.8, 163.9, 167.7, 190.9.

3d. (4-Fluoro-phenyl)-3-oxo-propionic acid ethyl ester

The general procedure was followed by using 0.5 mmol of 1-bromo-4-fluoro-benzene or 1-iodo-4-fluoro-benzene. Purification by flash chromatography using 0 to 5% of ethyl acetate in hexane gave the title compound 3d as a colourless liquid. Yield: 73 mg, 70% (X= Br) & 130 mg, 62% (X=I); LCMS: (M+H)+ 211.3; 1H-NMR (300 MHz, CDCl3): (Keto:Enol form) δ 1.26 (t, J = 7.11 Hz, 3H), 4.00 (s, 2H), 4.22 (q, J = 7.14 Hz, 2H), 7.13-7.26 (m, 2H), 8.00-8.20 (m, 2H); 13C-NMR (75MHz, CDCl3, δ ppm): 14.0, 45.9, 61.5, 115.7, 131.2, 167.7, 190.8.

3e. 3-(4-Chloro-phenyl)-3-oxo-propionic acid ethyl ester

The general procedure was followed by using 0.5 mmol of 1-Chloro-4-iodo-benzene. Purification by flash chromatography using 0 to 10% of ethyl acetate in hexane gave the title compound 3e as a colourless liquid. Yield: 84 mg, 74% (X= I). LCMS: (M+H)+ 227.5; 1H-NMR (400 MHz, CDCl3): (Keto:Enol form) δ 1.28 (t, 3H), 4.00 (s, 2H), 4.26 (q, 2H), 7.47-7.49 (m, 2H), 7.87-8.89 (m, 2H); 13C-NMR (100MHz, CDCl3, δ ppm): 14.1, 45.9, 61.5, 87.3, 128.7, 131.2, 133.7, 140.3, 167.5, 191.3.

3f. 3-(4-tert-Butyl-phenyl)-3-oxo-propionic acid ethyl ester

The general procedure was followed by using 0.5 mmol of 1-bromo-4-tert-Butyl-benzene or 1-iodo-4-tert-Butyl-benzene. Purification by flash chromatography using 0 to 5% of ethyl acetate in hexane gave the title compound 3f as a colourless liquid. Yield: 112 mg, 90% (X= Br) & 215 mg, 87% (X= I); UPLC: (M+H)+ 249.4; 1H-NMR (400 MHz, CDCl3): (Keto:Enol form) δ 1.27 (t, J = 9.56 Hz, 3H), 1.36 (s, 9H), 3.98 (s, 2H), 4.24 (q, J = 9.48 Hz, 2H), 7.48-7.51 (m, 2H), 7.87-7.90 (m, 2H); 13C-NMR (75MHz, CDCl3, δ ppm): 14.0, 30.9, 35.1, 45.9, 61.3, 125.8, 128.4, 133.4, 157.5, 167.6, 192.0.

3g. 3-Oxo-3-(4-trifluoromethyl-phenyl)-propionic acid ethyl ester

The general procedure was followed by using 0.5 mmol of 1-bromo-4-trifluoromethyl-benzene. Purification by flash chromatography using 0 to 5% of ethyl acetate in hexane gave the title compound 3g as a colourless liquid. Yield: 109 mg, 84%; UPLC: (M+H)+ 260.4; 1H-

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NMR (400 MHz, CDCl3): (Keto:Enol form)δ 1.28 (t, J = 2.56 Hz, 4.23H), 1.37 (t, J = 7.16 Hz, 2.14H), 4.04 (s, 2H), 4.18 (q, J = 71.48 Hz, 2H), 4.31 (q, J = 7.12 Hz, 1.44H), 5.74 (s, 0.6H), 7.69-7.71 (m, 1.4H), 7.77-7.79 (m, 2.147H), 7.89-7.91 (m, 3.18H), 8.07-8.09 (m, 1.99H); 13C-NMR (100MHz, CDCl3, δ ppm): 14.0,29.7, 46.1, 60.6, 61.7, 89.0, 125.5, 125.9, 128.9, 130.2, 167.0, 169.5, 172.9, 191.6.

3h. 3-(3-Methoxy-phenyl)-3-oxo-propionic acid ethyl ester

The general procedure was followed by using 0.5 mmol of 1-iodo-3-methoxy-benzene. Purification by flash chromatography using 0 to 10% of ethyl acetate in hexane gave the title compound 3h as a colourless liquid. Yield: 78 mg, 70% (X= Br) & 91 mg, 82% (X= I); UPLC: (M+H)+ 223.3; 1H-NMR (300 MHz, CDCl3): (Keto:Enol form) δ 1.26 (t, J = 7.14 Hz, 3H), 3.86 (s, 3H), 3.98 (s, 2H), 4.24 (q, J = 7.14 Hz, 2H), 7.12-7.12 (m, 1H), 7.39-7.32 (m, 2H), 7.53-7.50 (m, 2H); 13C-NMR (75MHz, CDCl3, δ ppm): 14.0, 46.0, 55.3, 61.4, 87.6, 111.0, 112.5, 117.2, 118.4, 120.3, 121.1, 129.5, 129.7, 134.8, 137.3, 159.9, 167.4, 192.2.

3i. 3-Biphenyl-4-yl-3-oxo-propionic acid ethyl ester

The general procedure was followed by using 0.5 mmol of 4-bromo-biphenyl or 4-iodo-biphenyl. Purification by flash chromatography using 0 to 10% of ethyl acetate in hexane gave the title compound 3i as a white solid. Yield: 120 mg, 90% (X= Br) & 117 mg, 88% (X= I); LCMS: (M+H)+ 269.3; 1H-NMR (400 MHz, CDCl3): (Keto:Enol form) δ 1.28 (t, J = 9.52 Hz, 3H), 4.03 (s, 2H), 4.24 (q, J = 9.52 Hz, 2H), 5.73 (s, 0.34H), 7.42-7.48 (m, 4H), 7.63-7.72 (m, 3H), 7.85-7.88 (m, 1H), 8.02-8.05 (m, 2H); 13C-NMR (75MHz, CDCl3, δ ppm): 14.1, 14.3, 46.1, 60.3, 61.5, 87.3, 126.5, 127.2, 127.4, 128.9, 129.0, 134.7, 139.6, 146.4, 167.6, 192.1.

3j. 3-Oxo-3-m-tolyl-propionic acid ethyl ester

The general procedure was followed by using 0.5 mmol of 1-Bromo-3-methyl-benzene or 1-Iodo-3-methyl-benzene. Purification by flash chromatography using 0 to 5% of ethyl acetate in hexane gave the title compound 3j as a colourless liquid. Yield: 68 mg, 66% (X= Br) & 75 mg, 73% (X= I); UPLC: (M+H)+ 207.3; 1H-NMR (400 MHz, CDCl3): (Keto:Enol form)δ 1.27 (t, 3H), 2.43 (s, 3H), 4.01 (s, 2H), 4.23 (q, J = 7.12 Hz, 2H), 5.67 (s, 0.4H), 7.30-7.43 (m, 2H), 7.74-7.77 (m, 2H); 13C-NMR (75MHz, CDCl3, δ ppm): 14.0, 14.2, 21.2, 21.3, 45.9, 61.3, 87.2, 125.7, 128.4, 128.9, 134.4, 136.0, 138.2, 167.5, 192.6.

3k. 3-(3-Chloro-5-fluoro-phenyl)-3-oxo-propionic acid ethyl ester

The general procedure was followed by using 0.5 mmol of 1-Bromo-3-chloro-5-fluoro-benzene. Purification by flash chromatography using 0 to 5% of ethyl acetate in hexane gave the title compound 3k as a colourless liquid. Yield: 99 mg, 81%; UPLC: (M+H)+ 245.7; 1H-NMR (400 MHz, CDCl3): (Keto:Enol form) δ 1.27 (t, J = 4.04 Hz, 3H), 1.35 (t, J = 7.12 Hz, 2.88H), 3.95 (s, 1H), 4.21-4.23 (m, 3.8H), 5.65 (s, 1H), 7.17-7.18 (m, 1H), 7.33-7.33 (m, 2.4H), 7.40-7.53 (m, 2.3H), 7.72-7.73 (m, 1.4H), 12.53 (s, 0.93H).

3l. 3-(3,5-Dimethoxy-phenyl)-3-oxo-propionic acid ethyl ester

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The general procedure was followed by using 0.5 mmol of 1-Bromo-3,5-dimethoxy-benzene. Purification by flash chromatography using 0 to 10% of ethyl acetate in hexane gave the title compound 3l as a colourless liquid. Yield: 70 mg, 56%; UPLC: (M+H)+ 253.3; 1H-NMR (400 MHz, CDCl3): (Keto:Enol form) δ 1.27 (t, J = 7.20 Hz, 3H), 3.84 (s, 7H), 3.96 (s, 2H), 4.20-4.22 (m, 2.2H), 6.57-6.57 (m, 1H), 7.08-7.09 (m, 2H); 13C-NMR (75MHz, CDCl3, δ ppm): 14.1, 46.1, 55.6, 61.5, 87.8, 106.0, 106.3, 137.9, 160.9, 167.4, 171.3, 192.2.

3m. 3-(3,5-Difluoro-phenyl)-3-oxo-propionic acid ethyl ester

The general procedure was followed by using 0.5 mmol of 1-Bromo-3,5-difluoro-benzene. Purification by flash chromatography using 0 to 5% of ethyl acetate in hexane gave the title compound 3m as a colourless liquid. Yield: 78 mg, 68%; UPLC: (M+H)+ 229.2; 1H-NMR (400 MHz, CDCl3): (Keto:Enol form)δ 1.27 (t, J = 7.04 Hz, 3.4H), 1.35 (t, J = 7.12 Hz, 3H), 3.95 (s, 2.37H), 4.26 (q, J = 7.16 Hz, 4.4H), 5.64 (s, 0.92H), 5.64-6.89 (m, 1H), 6.93-6.93 (m, 1.56H), 7.07-7.08 (m, 2.44H), 7.30-7.31 (m, 2.7H), 12.54 (s, 0.94H).

3n. 3-(3-Cyano-phenyl)-3-oxo-propionic acid ethyl ester

The general procedure was followed by using 0.5 mmol of 3-Bromo-benzonitrile. Purification by flash chromatography using 0 to 10% of ethyl acetate in hexane gave the title compound 3n as a colourless liquid. Yield: 65 mg, 60%; UPLC: (M+H)+ 218.3; 1H-NMR (400 MHz, CDCl3): (Keto:Enol form)δ 1.27 (t, J = 7.14 Hz, 3H), 1.35 (t, J = 7.14 Hz, 2H), 4.00 (s, 2H), 4.23 (q, J = 7.11 Hz, 2H), 4.29 (q, J = 4.53 Hz, 1.56H), 5.70 (s, 1H), 7.53-7.55 (m, 0.5H), 7.62-7.65 (m, 1H), 7.73-7.76 (m, 0.5H), 7.87-7.90 (m, 1H), 7.97-8.00 (m, 0.5H), 8.07-8.17 (m, 0.5H), 8.19-8.23 (m, 2H); 13C-NMR (75MHz, CDCl3, δ ppm): 14.1, 45.8, 60.7, 61.7, 88.9, 113.3, 129.6, 132.1, 134.8, 136.4, 166.6, .168.4, 172.7, 190.5.

3o. 3-(3,5-Dimethyl-phenyl)-3-oxo-propionic acid ethyl ester

The general procedure was followed by using 0.5 mmol of 1-Bromo-3,5-dimethyl-benzene. Purification by flash chromatography using 0 to 5% of ethyl acetate in hexane gave the title compound 3o as a colourless liquid. Yield: 85 mg, 77%; UPLC: (M+H)+ 221.3; 1H-NMR (400 MHz, CDCl3): (Keto:Enol form)δ 1.28 (t, J = 7.12 Hz, 3H), 2.39 (s, 6H), 3.99 (s, 2H), 4.24 (q, J = 7.12 Hz, 2H), 7.27 (s, 1H), 7.57 (s, 1H); 13C-NMR (75MHz, CDCl3, δ ppm): 14.0, 21.3, 46.0, 61.4, 87.2, 126.3, 135.4, 138.1, 167.7, 192.9.

3p. 3-(3-Benzoyl-phenyl)-3-oxo-propionic acid ethyl ester

The general procedure was followed by using 0.5 mmol of (3-Bromo-phenyl)-phenyl-methanone or 1-Iodo-4-methyl-benzene. Purification by flash chromatography using 0 to 10% of ethyl acetate in hexane gave the title compound 3p as a colourless liquid. Yield: (103 mg, 70%; LCMS: (M+H)+ 297.3; 1H-NMR (300 MHz, CDCl3): (Keto:Enol form) δ 1.29 (t, J = 9.52 Hz, 3H), 1.34 (t, J = 9.52 Hz, 1.8H), 4.00 (s, 2H), 4.22 (q, J = 9.48 Hz, 2H), 4.29 (q, J = 6.00 Hz, 1.2H), 5.69 (s, 1H), 7.55 (t, J = 10.48 Hz, 1H), 7.65 (t, J = 10.40 Hz, 0.7H), 7.74 (d, J = 10.24 Hz, 2H), 7.88 (d, J = 10.32 Hz, 1.2H), 7.98 (d, J = 10.64 Hz, 2H), 8.06 (s, 1H), 8.18 (d, J = 10.64 Hz, 2H), 8.23 (s, 1H), 12.59 (s, 1H); 13C-NMR (75MHz, CDCl3, δ ppm):

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14.0, 45.8, 60.7, 61.76, 88.9, 129.4, 129.6, 129.8, 129.9, 132.1, 132.5, 134.1, 134.7, 136.4, 136.7, 166.6, 168.4, 190.5.

3q. 4-(2-Ethoxycarbonyl-acetyl)-benzoic acid ethyl ester

The general procedure was followed by using 0.5 mmol of 4-Bromo-benzoic acid ethyl ester. 4-Iodo-benzoic acid ethyl ester. Purification by flash chromatography using 0 to 10% of ethyl acetate in hexane gave the title compound 3q as a colourless liquid. Yield: 73 mg, 55% (X= Br) & 98 mg, 74% (X= I); LCMS: (M+H)+ 265.3; 1H-NMR (300 MHz, CDCl3): (Keto:Enol form) δ 1.25 (t, J = 5.40 Hz, 2.76H), 1.34 (t, J = 5.10 Hz, 1.58H), 1.40 (t, J = 2.40 Hz, 4.2H), 4.02 (s, 1.68H), 4.22 (q, J = 5.10 Hz, 2H), 4.27 (q, J = Hz, 1.5H), 4.41 (q, J = 4.50 Hz, 2H), 5.73 (s, 0.84H), 7.83 (d, J = 6.60 Hz, 1H), 8.00 (d, J = 6.30 Hz, 1.65H), 8.08 (d, J = 6.60 Hz, 1H), 8.15 (d, J = 6.30 Hz, 1.65H); 13C-NMR (75MHz, CDCl3, δ ppm): 14.0, 14.2, 46.1, 60.5, 61.2, 61.4, 61.5, 88.9, 125.8, 128.3, 129.6, 129.8, 132.6, 134.7, 137.3, 139.0, 165.4, 165.8, 167.0, 169.9, 172.8, 192.0.

3r. 3-(3,5-Bis-trifluoromethyl-phenyl)-3-oxo-propionic acid ethyl ester

The general procedure was followed by using 0.5 mmol of 1-Bromo-3,5-bis-trifluoromethyl-benzene. Purification by flash chromatography using 0 to 5% of ethyl acetate in hexane gave the title compound 3r as a colourless liquid. Yield: 145 mg, 89%; LCMS: (M+H)+ 329.3; 1H-NMR (400 MHz, CDCl3): (Keto:Enol form) δ 1.29 (t, J = 7.12 Hz, 0.75H), 1.38 (t, J = 7.16 Hz, 3H), 4.07 (s, 0.5H), 4.26 (q, J = 7.12 Hz, 0.5H), 4.33 (q, J = 7.12 Hz, 2H), 5.80 (s, 1H), 7.98 (s, 1H), 8.23 (s, 2H), 8.41 (s, 0.5H); 13C-NMR (100MHz, CDCl3, δ ppm): 14.2, 45.9, 61.0, 62.0, 89.7, 121.4, 124.3, 126.7, 128.6, 135.7, 137.5, 166.4, 167.5, 172.6, 189.9.

3s. 3-Oxo-3-pyridin-3-yl-propionic acid ethyl ester

The general procedure was followed by using 1 mmol of 3-Bromo-pyridine. Purification by flash chromatography using 0 to 40 % of ethyl acetate in hexane gave the title compound 3s as a brown liquid. Yield: 137 mg, 71%; UPLC: (M+H)+ 194.2; 1H-NMR (400 MHz, CDCl3): (Keto:Enol form) δ 1.27 (t, J = 7.12 Hz, 3H), 1.35 (t, J = 7.12 Hz, 1.7H), 4.01 (s, 2H), 4.23 (q, J = 7.12 Hz, 2H), 4.29 (q, J = 7.12 Hz, 1H), 5.71 (s, 0.5H), 7.39-7.40 (m, 0.5H), 7.42-7.45 (m, 1H), 8.06-8.06 (m, 0.5H), 8.23 (m, 1H), 8.77 (m, 0.5H), 8.84-8.85 (m, 1H), 9.08 (s, 0.5H), 9.19 (s, 1H), 12.56 (s, 0.5H); 13C-NMR (100MHz, CDCl3, δ ppm): 14.0, 14.2, 46.0, 60.6, 61.7, 88.8, 123.9, 133.6, 135.8, 147.3, 149.9, 151.6, 154.0, 166.8, 168.7, 172.7, 191.4.

3t. 3-Oxo-3-thiophen-3-yl-propionic acid ethyl ester

The general procedure was followed by using 1 mmol of 3-Bromo-thiophene. Purification by flash chromatography using 0 to 5% of ethyl acetate in hexane gave the title compound 3t as a colourless liquid. Yield: 170 mg, 86%; LCMS: (M+H)+ 199.3; 1H-NMR (400 MHz, CDCl3): (Keto:Enol form) δ 1.28 (t, J = 7.12 Hz, 3H), 3.90 (s, 2H), 4.22 (q, J = 0.76 Hz, 2H), 7.35-7.35 (m, 1H), 7.56-7.57 (m, 1H), 8.13 (s, 1H).

3u. 3-Dibenzothiophen-2-yl-3-oxo-propionic acid ethyl ester

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The general procedure was followed by using 0.5 mmol of 2-Bromo-dibenzothiophene. Purification by flash chromatography using 0 to 5% of ethyl acetate in hexane gave the title compound 3u as a colourless liquid. Yield: 110 mg, 75%; LCMS: (M+H)+ 299.4; 1H-NMR (400 MHz, CDCl3): (Keto:Enol form) δ 1.29 (t, J = 7.20 Hz, 3H), 4.14 (s, 2H), 4.26 (q, J = 7.20 Hz, 2H), 7.50-7.51 (m, 2H), 7.86-7.89 (m, 1H), 7.91-7.94 (m, 1H), 8.03-8.03 (m, 1H), 8.25-8.26 (m, 1H), 8.77 (s, 1H); 13C-NMR (100MHz, CDCl3, δ ppm): 14.0, 46.2, 61.5, 121.8, 121.9, 122.9, 124.9, 126.2, 127.5, 132.5, 135.7, 167.5, 191.2.

3v. 3-(6-Fluoro-pyridin-3-yl)-3-oxo-propionic acid ethyl ester

The general procedure was followed by using 1 mmol of 5-Bromo-2-fluoro-pyridine. Purification by flash chromatography using 0 to 5% of ethyl acetate in hexane gave the title compound 3v as a colourless liquid. Yield: 139 mg, 66%; LCMS: (M+H)+ 212.2; 1H-NMR (400 MHz, CDCl3): (Keto:Enol form) δ 1.28 (t, J = 7.16 Hz, 3H), 1.35 (t, J = 7.12 Hz, 1H), 4.00 (s, 2H), 4.24 (q, J = 7.12 Hz, 2H), 4.29 (q, J = 7.16 Hz, 0.7H), 5.66 (s, 0.35H), 7.00-7.01 (m, 0.35H), 7.06-7.07 (m, 1H), 8.14-8.15 (m, 0.35H), 8.38-8.38 (m, 1H), 8.65 (s, 0.35H), 8.83 (s, 1H).

3w. 3-Dibenzofuran-2-yl-3-oxo-propionic acid ethyl ester

The general procedure was followed by using 0.5 mmol of 2-Iodo-dibenzofuran. Purification by flash chromatography using 0 to 5% of ethyl acetate in hexane gave the title compound 3w as a colourless liquid. Yield: 98 mg, 69%; UPLC: (M+H)+ 283.3; 1H-NMR (400 MHz, CDCl3): (Keto:Enol form) δ 1.29 (t, J = 7.20 Hz, 3H), 4.12 (s, 2H), 4.26 (q, J = 7.20 Hz, 2H), 7.41-7.42 (m, 1H), 7.52-7.54 (m, 1H), 7.61-7.63 (m, 2H), 8.03 (d, J = 7.20 Hz, 1H), 8.11 (d, J = 2.00 Hz, 1H), 8.61 (s, 1H); 13C-NMR (100 MHz, CDCl3, δ ppm): 14.1, 46.2, 61.5, 112.0, 121.0, 121.9, 122.9, 123.5, 128.2, 131.5, 156.9, 159.2, 167.6.

4. 1H NMR and 13C NMR spectral data of all the compounds (3a to 3w).

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