Cesium carbonate → HCID 46317762, compound

Participants

Reaction Conditions

Reaction Steps

A mixture of ethyl 5-bromothiophene-2-carboxylate (1.560 g, 6.65 mmol), pyridine-4-boronic acid (0.98 g, 7.98 mmol), tetrakis(triphenylphosphine)palladium(0) (768 mg, 0.665 mmol) and cesium carbonate (6.50 g, 19.9 mmol) in 1,4-dioxane (20 mL) and water (3.35 mL) was stirred and heated at 100° C. under an atmosphere of nitrogen overnight. The reaction was a clear light orange with a small amount of a second liquid phase on the bottom of the flask. An aliquot was taken, quenched into water, and extracted with ethyl acetate. A TLC on silica gel (1:1 DCM:hexane) indicated that all of the starting material had been consumed. A major new product with Rf ˜0.4 was seen. The reaction was cooled to room temperature then was quenched into stirring water and extracted with ethyl acetate. The ethyl acetate extracts were washed with saline, dried over sodium sulfate, filtered, and evaporated to leave crude product as an off-white solid. The crude product was dissolved in minimal DCM then was purified by column chromatography on silica gel (gradient 100% DCM to 50% ethyl acetate) to afford product 1.02 g (66% yield) as white solid. LC/MS (FA) ES+ 234. 1H NMR (400 MHz, DMSO) δ 8.68-8.60 (m, 2H), 7.91-7.83 (m, 2H), 7.78-7.71 (m, 2H), 4.37-4.27 (d, J=7.1 Hz, 2H), 1.35-1.27 (t, J=7.1 Hz, 3H).

Provenance & Evidence