Trifluoroacetic acid → Ethyl 1-(4-methoxyphenyl)-7-oxo-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridine-3-carboxylate

Participants

Reaction Conditions

Reaction Steps

Method B. A solution of 1-(4-methoxy-phenyl)-7a-morpholin-4-yl-7-oxo-3a,4,5,6,7,7a-hexahydro-1H-pyrazolo[3,4-c]pyridin-3-carboxylic acid ethyl ester (51, 402 mg, 1.0 mmol) in methylene chloride (CH2Cl2, 4 mL) was treated with trifluoroacetic acid (TFA, 1.0 mL) at 25° C., and the resulting reaction mixture was stirred at 25° C. for an additional 30 min. When HPLC and TLC showed the reaction was complete, the solvents were removed in vacuo. The residue was directly purified by flash column chromatography (SiO2, 5–30% EtOAc/hexane gradient elution) to afford the desired elimination product (50, 299 mg, 315 mg theoretical, 95%) as a pale-yellow oil, which solidified upon standing at room temperature in vacuo. This material was found to be identical with the product obtained from method A in every comparable aspect.

Provenance & Evidence