Methanol → 1-[2-(3,4-Dichloro-phenyl)-4-methyl-pent-2-enoyl]-3-methyl-urea

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Reaction Conditions

Reaction Steps

The isomeric mixture of 2-(3,4-dichloro-phenyl)-4-methyl-pent-2-enoic acid methyl ester [749.0 mg, 2.74 mmol, (E):(Z)=3.5:1] and methyl urea (812.6 mg, 10.97 mmol) were treated with a solution of magnesium methoxide in methanol (7.4 wt %, 16 mL, 10.97 mmol). The resulting reaction mixture was heated under reflux for 15 h. The reaction mixture was allowed to cool to 25° C. and then filtered through celite. The celite was thoroughly washed with ethyl acetate. The filtrate was concentrated in vacuo. Flash chromatography (Merck Silica gel 60, 230-400 mesh, 9/1 hexanes/ethyl acetate) afforded impure 1-[2-(3,4-dichloro-phenyl)-4-methyl-pent-2-enoyl]-3-methyl-urea (280.2 mg) as a white solid. A second flash chromatography (Merck Silica gel 60, 230-400 mesh, 3/2 hexanes/diethyl ether) again afforded impure 1-[2-(3,4-dichloro-phenyl)-4-methyl-pent-2-enoyl]-3-methyl-urea (114.6 mg) as a white solid. Recrystallization from hexanes/ethyl acetate afford pure (E)-1-[2-(3,4-dichloro-phenyl)-4-methyl-pent-2-enoyl]-3-methyl-urea (24.7 mg, 3%) as a white solid: mp 177-178° C.; FAB-HRMS m/e calcd for C14H16Cl2N2O2 (M+H)+315.0667, found 315.0652.

Provenance & Evidence