Ethanol → Ethyl 4-ethoxy-1-ethyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylate

Participants

Reaction Steps

Sodium (0.55 g, 23.7 mmol) was added portionwise to anhydrous ethanol (25 ml) at 20° C. under an atmosphere of nitrogen. After stirring for 1 hour the solution was added to Intermediate 1 (4.622 g, 18.22 mmol) and the reaction mixture heated at reflux for 2 hours. The mixture was evaporated in vacuo and the residue partitioned between dichloromethane and water. The organic phase was washed with brine, dried (Na2SO4) and evaporated in vacuo. The residue was purified on SPE cartridges (silica, 4×20 g) eluting with dichloromethane, ethyl acetate:petroleum ether (1:4, 1:2 then 1:1) followed by ethyl acetate). Appropriate fractions were combined and evaporated in vacuo to afford Intermediate 35 as white solid (4.33 g). LCMS showed MH+=264, TRET=2.77 min.

Provenance & Evidence