Hydrochloric Acid → (S)-2'-oxo-1',2',5,7-tetrahydrospiro(cyclopenta(b)pyridine-6,3'-pyrrolo(2,3-b)-bipyridine)-3-carboxylic acid

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Reaction Conditions

Reaction Steps

A mixture of methyl (6S)-2′-oxo-1′,2′,5,7-tetrahydrospiro[cyclopenta[b]pyridine-6,3′-pyrrolo[2,3-b]pyridine]-3-carboxylate (30.0 g, 102 mmol) and aqueous 6 N sodium hydroxide solution (50.8 mL, 305 mmol) in MeOH (920 mL) was heated at reflux for 1 h. The mixture was allowed to cool to 23° C. before it was acidified to pH ˜6 with aqueous 1 N hydrochloric acid solution, resulting in a black precipitate which was removed by filtration. The filtrate was concentrated under reduced pressure to a volume of ˜100 mL and then partitioned between water (500 mL) and 2-methyltetrahydrofuran (2-MeTHF, 250 mL). The aqueous layer was extracted with 2-MeTHF (5×250 mL), and the combined organic layers were dried over sodium sulfate and concentrated to provide the title compound. MS: m/z=282.0 (M+1).

Provenance & Evidence