Iron → Fe Ac2O AcOH

Participants

Reaction Conditions

Reaction Steps

A mixture of spray-dried KF (1.07 g, 18.58 mmol), intermediate 2 (500 mg, 1.858 mmol) and catalytic amount of 18-crown-6 in dry DMSO (8 mL) was stirred at 170-180° C. for 30 min. Work-up of the reaction mixture as described in example 1 gave the residue. This residue was dissolved in a mixture of AcOH and Ac2O (12 mL, 1:1) and added iron powder (2.08 g, 37.17 mmol) at rt. The mixture was stirred at 60-70° C. for 30 min and diluted with EtOAc (25 mL). Filtered the solution to remove iron powder and washed with few mL of EtOAc. Ethyl acetate was removed under reduced pressure. The residue was chromatographed over silica gel column using chloroform:methanol (70:30) as eluents to give the product as a white color solid (160 mg, 34%), mp 240-242° C. 1H NMR (400 MHz, DMSO-d6): δ 10.51 (1H, s, exchangeable with D2O), 7.82 (1H, br s, exchangeable with D2O), 7.76 (1H, t, J=8.6 Hz), 7.70 (1H, d, J=14.0 Hz), 7.34 (1H, d, J=8.4 Hz), 3.71 (2H, s), 2.08 (3H, s); LC-MS (negative ion mode): m/z 253 (M−H)−.

Provenance & Evidence