Thiophene, 2-nitro- → Ethyl 7-thienylamino-1H-pyrazolo[4,3-b]pyridine-6-carboxylate

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Reaction Steps

Ethyl 7-chloro-1H-pyrazolo[4,3-b]pyridine-6-carboxylate (4.5 g 0.02 mole) and aminothiophene (2.0 g) [prepared from 2-nitrothiophene (supplied by Aldrich and shown by nmr to contain 15% of 3-nitrothiophene) by reduction using either H2 ; 10% Pd/C or stannous chloride] were stirred together under nitrogen for 24 hours. The ethanol was removed under reduced pressure. The resulting brown oil was purified by column chromatography on silica eluting with 5% methanol/ether to give the title compound as a beige solid (0.600 g), mp 188°-190° C.

Provenance & Evidence