Tetrahydrofuran → 2H-Pyrano[3,2-b]pyridine-3-carboxylic acid, ethyl ester

Participants

Reaction Conditions

Reaction Steps

A mixture of NaH 60% (0.051 mol) in THF (20 ml) was stirred at 0° C. A solution of 3-hydroxy-2-pyridinecarboxaldehyde (0.034 mol) in THF (75 ml) was added dropwise at 0° C. The reaction mixture was stirred for one hour at room temperature. A solution of 2-(diethoxyphosphinyl)-2-propenoic acid, ethyl esther (0.041 mol) in THF (75 ml) was added portionwise at 0° C. The reaction mixture was stirred for 24 hours at room temperature, then stirred and refluxed for 4 hours, then stirred for 24 hours at room temperature. A 10% aqueous NH4Cl solution was added and the mixture was extracted with DCM. The separated organic layer was dried, filtered and the solvent evaporated. The residue was purified by short open column chromatography over silica gel. The desired fractions were collected and the solvent was evaporated, yielding 0.56 g of 2H-pyrano[3,2-b]pyridine-3-carboxylic acid, ethyl ester (intermediate 24).

Provenance & Evidence