Thionyl Chloride → [2-(2,5-Dichloro-phenoxy)-pyridin-3-yl]-(3,4-dihydro-2H-quinoxalin-1-yl)-methanone

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Reaction Steps

A solution of 2-(2,5-dichloro-phenoxy)-nicotinic acid (100 mg, 0.35 mmol, 1.0 equiv; Example 31, Step 1) in thionyl chloride (3.28 g, 2 ml, 27.6 mmol, 230 equiv; [CAS RN 7719-09-7]) was heated to 100° C. for 1 h. The reaction mixture was concentrated under reduced pressure, remaining thionyl chloride removed by azotropic distillation with toluene and the residue dissolved in anhydrous DMF (1 mL). To this solution was added N-ethyldiisopropylamine (452 mg, 595 μL, 3.5 mmol, 10.0 equiv; [CAS RN 7087-68-5]) and 1,2,3,4-tetrahydro-quinoxaline (56 mg, 0.42 mmol, 1.2 equiv; [CAS RN 3476-89-9]) and the reaction mixture was stirred at rt for 2 h. 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 17.3 mg (12%) of the title compound. MS (ISP): 400.0 [M+H]+.

Provenance & Evidence