Heptane → 4-(3-Bromo-4-fluorophenyl)-3-(4-((2-hydroxyethyl)amino)-1,2,5-oxadiazol-3-yl)-1,2,4-oxadiazol-5(4H)-one

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Reaction Steps

To a solution of 4-(3-bromo-4-fluorophenyl)-3-(4-(2-methoxyethylamino)-1,2,5-oxadiazol-3-yl)-1,2,4-oxadiazol-5(4H)-one (can be prepared according to Example 1, steps A-G; 1232 g, 3.08 mol) in dichloromethane (12 L) stirring in a 22 L flask at 0° C. was added boron tribromide (354 mL, 3.67 mL) dropwise at a rate so that the temperature did not exceed 10° C. After stirring on ice for 1 h, a solution of saturated aqueous sodium bicarbonate (2 L) was carefully added at a rate so that the temperature did not exceed 20° C. (addition time 10 min). The resulting mixture was transferred to a 50 L separatory funnel, diluted with water (10 L), and the pH of the aqueous layer adjusted from 1 to 8 using solid sodium bicarbonate. The layers were separated, and the organic layer was washed with water (10 L), and the solvents removed in vacuo to afford a tan solid (24 mol processed in multiple runs, 9.54 kg, quant. yield). The material was slurried in 4 volumes of 7:1 heptane:ethyl acetate (4×22 L flasks), filtered, and dried to furnish the title compound as a tan solid (8679 g, 94%). The product was a mixture of the hydroxy- and the corresponding bromo-species.

Provenance & Evidence