Methanol → 4-(3-dimethylaminopropyl)-2-methyl-1H-pyrrole-3-carboxylic acid ethyl ester

Participants

Reaction Steps

To a heterogeneous mixture of 4-(2-dimethylcarbamoyl-ethyl)-2-methyl-1H-pyrrole-3-carboxylic acid ethyl ester (1.01 g, 4 mmol) in tetrahydrofuran (9 mL) was added dropwise 8 mL of borane-tetrahydrofuran complex (1M solution in tetrahydrofuran). The mixture was heated to reflux overnight. Nine mL of methanol was added slowly to the reaction and the heating was continued for another 2 hours. The cooled reaction was quenched with 1 N hydrochloric acid and extracted with ethyl acetate. The aqueous layer was basified with aqueous potassium hydroxide, extracted with ethyl acetate, and the organic layer washed with brine, dried and concentrated to give 616 mg (65% yield) of 4-(3-dimethylamino-propyl)-2-methyl-1H-pyrrole-3-carboxylic acid ethyl ester as a faint orange oil. 1H-NMR (360 MHz, dimethylsulfoxide-d6) δ 10.84 (br s, 1H, NH), 6.36 (d, 1H), 4.12 (q, 2H, OCH2), 2.52 (m, 2H, CH2), 2.34 (s, 3H, CH3), 2.17 (m, 2H, CH2), 2.08 (s, 6H, N(CH3)2), 1.57 (m, 2H, CH2), 1.23 (t, 3H, CH3).

Provenance & Evidence