Water → ethyl 3-bromo-4-cyano-5-(3,6-dihydro-2H-pyran-4-yl)thiophene-2-carboxylate

Participants

Reaction Conditions

Reaction Steps

To a microwave vial containing a suspension of ethyl 3,5-dibromo-4-cyanothiophene-2-carboxylate (300.0 mg, 0.8849 mmol, prepared as in MPI10-008P1M) and 3,6-dihydro-2h-pyran-4-boronic acid pinacol ester (204 mg, 0.973 mmol) in 1,4-dioxane (8.98 mL, 115 mmol) and water (0.925 mL, 51.3 mmol) were added tetrakis(triphenylphosphine)palladium(0) (102 mg, 0.0885 mmol) and cesium carbonate (865 mg, 2.65 mmol). The vial was sealed, degassed by bubbling argon through for 10 minutes, and then heated at 100° C. with stirring for 24 h. The reaction was then cooled to room temperature and partitioned between EtOAc and water. Layers were separated, and, the aqueous layer was extracted 2× with EtOAc. Combined organic layers were dried over Na2SO4, filtered, and concentrated in vacuo. Residue was subjected to column chromatography as a solution in DCM (40 g column, gradient elution 0 to 25% EtOAc/hexanes) to afford ethyl 3-bromo-4-cyano-5-(3,6-dihydro-2H-pyran-4-yl)thiophene-2-carboxylate as a white solid (183 mg, yield 63%). LCMS: (FA) ES+ 342, 344; 1H NMR (400 MHz, DMSO) δ 6.86-6.79 (m, 1H), 4.36-4.27 (m, 4H), 3.82 (dd, J=5.4, 5.4, 2H), 2.53 (ddd, J=2.1, 4.9, 10.0, 2H), 1.30 (dd, J=7.1, 7.1, 3H).

Provenance & Evidence