Acetyl chloride → 1-[5-Hydroxy-2-(4-hydroxy-phenyl)-benzofuran-3-yl]-ethanone

Participants

Reaction Steps

A solution of the bis-pivaloylate 109 (1 g, 2.54 mmol) in CH2Cl2 was treated with acetyl chloride (0.22 g, 2.8 mmol) was treated with AlCl3 (0.36 g, 2.8 mmol) and stirred at rt overnight. The reaction was worked up by adding EtOAc, washing with 2 N HCl aq, saturated NaHCO3 aq and drying over MgSO4. After filtering and concentrating, the residue was chromatographed on silica gel (EtOAc/hexanes 1:4 to EtOAc/hexanes 1:1) to yield the product which was promptly dissolved in MeOH/THF/2 N NaOH aq and warmed until TLC analysis indicated that the hydrolysis of the pivalate esters was completed. The reaction was concentrated to remove the organic solvents and the residue aqueous was acidified with 2 N HCl aq and extracted with EtOAc. The EtOAc extract was washed with saturated NaHCO3 solution, brine and dried over MgSO4. After filtration and concentration, the residue was chromatographed on silica gel (EtOAc/hexanes 1:4 to EtOAc/hexanes 1:1) to yield 90 mg of the desired pdt: Mp=243-251° C.; 1H NMR (DMSO-d6) δ 10.08 (br s, 1 H), 9.40 (br s, 1 H), 7.63 (d, 2 H, J=8.8 Hz), 7.43 (d, 1 H, J=9.3 Hz), 7.41 (d, 1 H, J=2.4 Hz), 6.92 (d, 2 H, J=8.8 Hz), 6.80 (dd, 1 H, J=8.8 Hz, 2.4 Hz), 2.26 (s, 3 H).

Provenance & Evidence