Sodium hydride → 4-{4-[2-(2,5-Dichloro-phenoxy)-5-fluoro-pyridine-3-carbonyl]-3,4-dihydro-2H-quinoxalin-1-yl}-butyric acid ethyl ester

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Reaction Steps

To a solution of [2-(2,5-dichloro-phenoxy)-5-fluoro-pyridin-3-yl]-(3,4-dihydro-2H-quinoxalin-1-yl)-methanone (50.2 mg, 0.12 mmol, 1.0 equiv; Example 147) in anhydrous DMF (1 mL) was added sodium hydride (10.3 mg, 0.24 mmol, 2.0 equiv; 55% free-flowing powder moistened with oil; [CAS RN 7646-69-7]) and the reaction mixture stirred at rt. After 1 h, 4-bromo-butyric acid ethyl ester (545 mg, 400 μL, 2.80 mmol, 23.3 equiv; [CAS RN 2969-81-5]) was added and stirring continued under microwave heating to 120° C. for 30 min. Removal of the solvent mixture under reduced pressure and purification by preparative HPLC on reversed phase (Xterra® PrepMSC 18, 5 μm, 19×50 mm column equipped with a Gilson Liquid Handler 215 autosampler, two Rainin Dynamax® SD-300 pumps, a Sedex ELSD 75 lightscatter and a Dionex UVD 340S UV detector) eluting with a gradient of acetonitrile/water provided 5.5 mg (9%) of the title compound as a light yellow oil. MS (ISP): 532.2 [M+H]+.

Provenance & Evidence