Cesium carbonate → 4-Iodo-1-[2-(tetrahydro-pyran-2-yloxy)-ethyl]-1H-pyrazole-3-carboxylic acid ethyl ester

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Reaction Steps

A suspension of Intermediate 74b (2.72 g, 10.2 mmol) in acetonitrile (27 mL) was treated with caesium carbonate (5.0 g, 15.3 mmol) then 2-(2-bromoethoxy)tetrahydro-2H-pyran (1.70 mL, 11.2 mmol) and the mixture was stirred at 60° C. for 3.5 h. The mixture was evaporated in vacuo and the residue was partitioned between EtOAc and water. The aqueous layer was then extracted with EtOAc (2×). The combined organic layers were washed with saturated aqueous sodium bicarbonate solution and brine, dried (Na2SO4), filtered and evaporated in vacuo. The residue was purified by FCC, using 0-50% EtOAc in cyclohexane, isolating the lower running spot to give the title compound as a colourless glass (1.57 g, 39%). LCMS (Method 3): Rt 3.67 min, m/z 417 [M+Na+].

Provenance & Evidence