Potassium Carbonate → (6'-hydroxy-3-oxospiro[isobenzofuran-1(3H), 9'-[9H]xanthen]-3'-yl)oxy-acetic acid methyl ester

Participants

Reaction Conditions

Reaction Steps

Methyl bromoacetate (0.25 mL, 2.65 mmol) was added dropwise to a stirred mixture of 21 (0.33 g, 0.89 mmol) and K2CO3 (0.36 g, 2.65 mmol) in dry DMF (20 mL) under argon. The resulting mixture was stirred for 4 h at 90° C. The mixture was concentrated, diluted with ethyl acetate, washed with 10% NaHCO3, brine, dried with anhydrous Na2SO4, and evaporated. The residue was dissolved in dry DCM (25 mL). Tetrakis(triphenylphosphine) palladium(0) (58 mg, 0.05 mmol) and phenylsilane (1.1 mL, 8.90 mmol) were added. The mixture was stirred for 2 h at room temperature and concentrated. The residue was purified by column chromatography (ethyl acetate/hexane=1:1) to give 22 as a yellow solid (0.22 g, 62%). TLC (ethyl acetate/hexane, 3:1): Rf=0.5. mp 236° C. 1H NMR (CDCl3/CD3OD, 500 MHz) δ 3.76 (s, 3H, CO2CH3), 4.69 (s, 2H, CH2), 6.68 (m, 6H), 7.19 (d, J=7.5 Hz, 1H), 7.66 (t, J=7.5 Hz, 1H), 7.71 (t, J=7.5 Hz, 1H), 8.01 (d, J=7.5 Hz, 1H). 13C NMR (CDCl3/CD3OD, 125 MHz) δ 52.33, 65.18, 101.86, 102.77, 109.84, 111.55, 112.37, 112.52, 124.05, 124.87, 126.67, 129.00, 129.24, 129.80, 135.21, 152.47, 152.56, 152.94, 159.34, 169.21, 170.15, 171.36, 172.03. ESIMS calcd for C23H17O7 [M+H]+ 405.1. Found 405.2.

Provenance & Evidence