2-Methoxy-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)aniline → N-(2-methoxy-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-6-methyl-6H-thieno[2,3-b]pyrrole-5-carboxamide

Participants

Reaction Steps

To 4-amino-3-methoxyphenylboronic acid pinacol ester (1340 mg, 5.38 mmol) in tetrahydrofuran (20 ml) under a nitrogen atmosphere was added slowly a 2M solution of ethylmagnesium chloride in tetrahydrofuran (2.69 ml, 5.38 mmol) and the resulting solution was heated at reflux for one hour. Methyl 6-methyl-6H-thieno[2,3-b]pyrrole-5-carboxylate (500 mg, 2.56 mmol) was added and the reaction mixture was heated at reflux for 18 hours. The reaction mixture was cooled to room temperature and poured in brine. The mixture was extracted three times with ethyl acetate and the combined organic layers were washed subsequently with water and brine. The organic layer was dried (Na2SO4) and concentrated in vacuo. The residue was purified by column chromatography (silica gel; heptane with gradient of 0 to 50% of ethyl acetate). The product was dissolved in hot dichloromethane and the remaining solids were removed by filtration. The filtrate was concentrated, the residue dissolved in hot dichloromethane and diethylether was added. The formed solids were collected by filtration, washed with diethylether and dried to yield N-(2-methoxy-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-6-methyl-6H-thieno[2,3-b]pyrrole-5-carboxamide (343 mg).

Provenance & Evidence