Hydroxyamine hydrochloride → 1-[5-Hydroxy-2-(4-hydroxy-phenyl)-benzofuran-3-yl]-ethanone oxime

Participants

Reaction Steps

Ketone 110 (1.9 g, 7.1 mmol) was dissolved in a solution of EtOH/Pyr (50 mL/10 mL) and treated with NH2OH—HCl (0.5 g, 7.2 mmol) and heated at reflux until all of the starting material was consumed by TLC analysis. The reaction was worked up by concentrating down and partitioning the residue between EtOAc and 2 N HCl aq, washing the EtOAc layer with saturated NaHCO3 aq, brine and drying over MgSO4. The solution was then filtered, concentrated and chromatographed on silica gel (1:4 EtOAc/hexanes) and the product obtained triturated with CH2Cl2 to yield 0.131 g of the pure oxime. Stereochemistry of the oxime was tentatively defined as cis since no NOE effect between the oxime hydroxyl proton and the adjacent methyl group could be observed: Mp=217° C.; 1H NMR (DMSO-d6) δ 11.27 (s, 1 H), 9.94 (br s, 1 H), 9.23 (br s, 1 H), 7.51 (d, 2 H, J=8.8 Hz), 7.36 (d, 1 H, J=8.3 Hz), 7.03 (d, 1 H, J=2.4 Hz), 6.88 (d, 2 H, J=8.8 Hz), 6.74 (dd, 1 H, J=8.8 Hz, 2.4 Hz), 1.99 (s, 3 H).

Provenance & Evidence