[CH2:1]([O:3][C:4]([C:6]1[NH:7][C:8]2[C:13]([CH:14]=1)=[CH:12][C:11]([OH:15])=[CH:10][CH:9]=2)=[O:5])[CH3:2].Br[CH2:17][CH2:18][CH2:19][Cl:20].C(=O)([O-])[O-].[K+].[K+]>CC(=O)CC>[CH2:1]([O:3][C:4]([C:6]1[NH:7][C:8]2[C:13]([CH:14]=1)=[CH:12][C:11]([O:15][CH2:17][CH2:18][CH2:19][Cl:20])=[CH:10][CH:9]=2)=[O:5])[CH3:2]A mixture of ethyl-5-hydroxyindole-2-carboxylate (purchased at Biosynth, Ref H-6350, 15 g, 1.0 eq.), 1-bromo-3-chloropropane (8.8 mL, 1.2 eq.) and potassium carbonate (12.12 g, 1.2 eq.) in butanone (200 mL) was stirred 4 days at reflux. The reaction mixture was partitioned between ethyl acetate and water. The aqueous layer was extracted with ethyl acetate. The combined organic layers were washed with water and brine, evaporated in vacuo and purified on silica, eluting with a 19:1 to 2:1 gradient of cyclohexane/ethyl acetate to yield 15.3 g (74%) of the desired product as light yellow solid. MS (m/e): 282.5 (MH+, 100%).
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