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.
