Dimethylformamide → Ethyl 3-(4-chloro-3-fluorobenzyl)-4-cyano-5-morpholin-4-ylthiophene-2-carboxylate

Participants

Reaction Steps

In a flame-dried scintillation vial, to a suspension of zinc (0.0998 g, 1.53 mmol) in N,N-dimethylformamide (1.36 mL, 17.6 mmol) were added 1,2-dibromoethane (0.003279 mL, 0.03805 mmol) and chlorotrimethylsilane (0.004830 mL, 0.03805 mmol). Stirred at room temperature for 15 min, at which point a solution of 3-fluoro-4-chlorobenzylbromide (0.341 g, 1.53 mmol) in N,N-dimethylformamide (1.36 mL, 17.6 mmol) was added. The resulting suspension was stirred at room temperature for 16 hours. A scintillation vial containing ethyl 4-cyano-3-iodo-5-morpholin-4-ylthiophene-2-carboxylate (199 mg, 0.507 mmol and bis(tri-t-butylphosphine)palladium(0) (12.96 mg, 0.02537 mmol) was purged via vacuum/backfilling with argon. To this was added the organozinc solution from above, and the resulting solution was stirred at 45° C. for 6 hours, at which point LC/MS showed complete conversion to a single new peak with mass representing desired product. The reaction mixture was transferred to a separatory funnel containing saturated NaHCO3 (aq., 10 mL) and water (10 mL), and then diluted with EtOAc (40 mL). The layers were separated, and the aqueous layer was extracted 2×30 mL with EtOAc. The combined organic layers were washed 1× brine, dried over Na2SO4, filtered, and concentrated in vacuo to afford crude ethyl 3-(4-chloro-3-fluorobenzyl)-4-cyano-5-morpholin-4-ylthiophene-2-carboxylate as a brown oil that was used without further purification. LCMS: (FA) ES+ 409, 411

Provenance & Evidence