N,N-dimethylhydroxylamine hydrochloride → 1-Ethyl-4-(3-methoxy-phenylethynyl)-1H-pyrrole-2-carboxylic acid methyl amide

Participants

Reaction Steps

This intermediate (2.5 g, 9.28 mmol) was treated with oxalyl chloride (4.1 mL, 46.4 mmol), DMF (2 drops) in methylene chloride (70 mL) and stirred at room temperature for 2 hours to give 1-ethyl-4-(3-methoxy-phenylethynyl)-1H-pyrrole-2-carboxylic acid chloride (2.7 g, 9.38 mmol) after a usual workup. 1-Ethyl-4-(3-methoxy-phenylethynyl)-1H-pyrrole-2-carboxylic acid chloride (2.7 g, 9.38 mmol) was diluted with methylene chloride (35 mL) and added to a prepared solution of N,O, dimethyl-hydroxylamine hydrochloride (4.6 g, 46.4 mmol) and diisopropyl-ethyl amine (13 mL, 74.3 mmol) in methylene chloride (35 mL) over 5 minutes. The reaction was complete after 4 hours. Solvent was removed in vacuo and the residue was taken back in a mixture of saturated aqueous NH4Cl: H2O (1:1, 150 mL) solution and extracted with ether. Combined ether extracts were washed with brine dried (MgSO4) and filtered. Evaporation and purification by flash chromatography (hexane/ethyl acetate 9/1) gave the title compound as a light yellow oil (2.48 g g, 82% yield), 1H NMR (400 MHZ, CDCl3) □ 1.35-1.37 (t, 3H), 3.31 (s, 3H), 3.67 (s, 3H), 3.78 (s, 3H), 4.29-4.30 (q, 2H), 6.83 (m, 1H), 6.99 (m, 2H), 7.01 (m, 2H), 7.19 (m, 1H), MS m/e (M+H)+ 313.1.

Provenance & Evidence