4-Pentenoic acid, 5-(3,4-methylenedioxyphenyl)-3-oxo-, ethyl ester

4-Pentenoic acid, 5-(3,4-methylenedioxyphenyl)-3-oxo-, ethyl ester

cas 860547-52-0

MF C14 H14 O5

4-Pentenoic acid, 5-(1,3-benzodioxol-5-yl)-3-oxo-, ethyl ester

Molecular Weight, 262.26

Melting Point (Experimental)

Value: 58-60 °C

Purification of the residue by flash column chromatography (10% ethyl acetate in hexanes) afforded the β-keto ester (12.0 g, 90%) as a pale yellow oil. Compound 3

1H-NMR (400 MHz, CDCl3), δ (ppm):12.00 (s, 0.4 H, enol OH), 7.52 (d, 1H, J = 16.0 Hz, C5 keto ), 7.35 (t, J = 15.6, 1H, C6’ keto), 7.05 (complex, 1.4H, C2’ keto, C2’ enol ), 7.03 (d, J = 12.8, 1H, C5’ keto), 6.97 (d, J = 8.0 Hz, 0.5H, C5’ enol), 6.83-6.78 (m, 1.5H, C6’, C5 and C2 enol), 6.65 (d, J = 16.0 Hz, 1H, C4 keto), 6.27 (d, J = 16 Hz, 0.5H, C4 enol), 6.02 (s, 2H, C7’ keto), 5.98 (s, 1H, C7’ enol), 4.22 (complex, 3H, COOCH2CH3, keto and enol), 3.66 (s, 2H, C2 keto), 1.29 (complex, 4.7H, COOCH2CH3 keto and enol);

13C-NMR (100 MHz, CDCl3), δ (ppm): 191.7, 172.8, 169.4, 167.5, 150.2, 148.8, 148.4, 148.2, 144.4, 136.4, 129.8, 128.4, 125.4, 123.5, 123.2, 119.9, 108.6, 108.5, 106.6, 106.1, 101.7, 101.4, 91.3, 77.3, 77.0, 76.7, 61.4, 60.1, 47.6, 14.2, 14.1.

 

1H NMR PREDICT

 

13C NMR PREDICT

 

/////////

Org. Chem. Front., 2017, Advance Article,
DOI: 10.1039/C7QO00021A

and

1. English, James, Jr.; Journal of the American Chemical Society 1943, V65, P2466-7 
2. (2) Borsche, W.; Berichte der Deutschen Chemischen Gesellschaft [Abteilung] B: Abhandlungen 1933, V66B, P1792-801 

O=C(OCC)CC(=O)/C=C/c1ccc2OCOc2c1

α-Chloro-[2-(ethoxycarbonyl)-3-methoxy]benzeneacetic acid, Ethyl ester

Procedure for the Insertion into α-Chloromalonate 4a

To a suspension of CsF (183 mg, 1.2 mmol) in MeCN (2.0 mL) were added diethyl α-chloromalonate (4a, 32 µL, 0.20 mmol) and 3-methoxy-2-(trimethylsilyl)phenyl triflate (1, 63 µL, 0.24 mmol) under argon atmosphere at −20 °C. After being stirred at −20 °C to room temperature for 12 h, the reaction mixture was diluted with saturated NaHCO3 and then extracted with AcOEt. The organic phase was dried over Na2SO4 and concentrated at reduced pressure. Purification of the residue by PTLC (AcOEt/hexane =1:2) afforded the product 9 (31 mg, 52%).

α-Chloro-[2-(ethoxycarbonyl)-3-methoxy]benzeneacetic acid, Ethyl ester (9). 

IR (KBr) 2983, 1752, 1736, 1589, 1472, 1442 cm−1. 

1H-NMR (CDCl3) δ 7.40 (1H, t, J = 8.2 Hz), 7.25 (1H, br d, J = 8.5 Hz), 6.93 (1H, br d, J = 8.5 Hz), 5.50 (1H, s), 4.42 (2H, q, J = 7.1 Hz), 4.27–4.15 (2H, m), 3.83 (3H, s), 1.39 (3H, t, J= 7.1 Hz), 1.24 (3H, t, J = 7.1 Hz). 

13C-NMR (CDCl3) δ 167.8, 166.5, 156.6, 134.6, 131.2, 123.2, 120.4, 111.9, 62.6, 61.7, 56.1, 55.6, 14.1, 13.9. 

HRMS (ESI+) calcd for C14H1735ClO5Na (M+Na+): 323.0657, Found: 323.0642; HRMS (ESI+)calcd for C14H1737ClO5Na (M+Na+): 325.0633, Found: 325.0613.

4-Methoxy-2-benzofurancarboxylic acid, Ethyl ester

4-Methoxy-2-benzofurancarboxylic acid, Ethyl ester

Procedure for the Synthesis of Benzofuran 15a

To a suspension of CsF (304 mg, 2.0 mmol) in DMF (4.0 mL) were added 3-methoxy-2-(trimethylsilyl)phenyl triflate (1, 105 µL, 0.40 mmol) and ethyl iodoacetate 14 (95 µL, 0.80 mmol) under argon atmosphere at 100 °C. After being stirred at the same temperature for 12 h, the reaction mixture was diluted with saturated NaHCO3 and then extracted with CH2Cl2. The organic phase was dried over Na2SO4 and concentrated at reduced pressure. Purification of the residue by flash silica gel column chromatography (EtOAc/hexane = 1:20–1:4) afforded the product 15a (35 mg, 40%). Product 16 was also formed.

4-Methoxy-2-benzofurancarboxylic acid, Ethyl ester (15a). Colorless oil. 

IR (KBr) 2981, 1726, 1609, 1570, 1500 cm−1. 

1H-NMR (CDCl3) δ 7.62 (1H, d, J = 1.0 Hz), 7.35 (1H, t, J = 8.2 Hz), 7.18 (1H, d, J = 8.2 Hz), 6.67 (1H, d, J = 8.2 Hz), 4.43 (2H, q, J = 7.1 Hz), 3.94 (3H, s), 1.41 (3H, t, J = 7.1 Hz). 

13C-NMR (CDCl3) δ 159.5, 156.9, 154.6, 144.4, 128.5, 117.8, 111.6, 105.1, 103.5, 61.4, 55.6, 14.3. 

HRMS (ESI+) calcd for C12H13O4 (M+H+): 221.0808, Found: 221.0806.

Procedure for Transformation of Dihydrobenzofuran 8a into Benzofuran 15a

To a solution of dihydrobenzofuran 8a (50 mg, 0.16 mmol) in THF (3.2 mL) was added KHMDS (0.50 M in toluene, 320 µL, 0.16 mmol) under argon atmosphere at −40 °C. After being stirred at the same temperature for 12 h, the reaction mixture was diluted with saturated NaHCO3 and then extracted with CH2Cl2. The organic phase was dried over Na2SO4 and concentrated at reduced pressure. Purification of the residue by PTLC (EtOAc/hexane = 1:4 with 2% CH2Cl2) afforded benzofuran 15a (33 mg, 96%).
http://www.mdpi.com/1420-3049/19/1/863/htm