Malononitrile → tert-Butyl 2-amino-3-cyano-4,7-dihydrofuro[2,3-c]pyridine-6(5H)-carboxylate

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Reaction Steps

tert-Butyl 3-hydroxy-4-oxopiperidine-1-carboxylate from Example 45A (3.88 g, 64% purity, 11.5 mmol) was dissolved in ethanol (10 mL), and propanedinitrile (758 mg, 11.5 mmol) was added. Within 10 min, diethylamine (0.84 g, 11.5 mmol) was added dropwise, whilst the temperature was kept below 30° C. Subsequently, the reaction mixture was stirred for 20 h at rt. The solvent was removed in vacuo, and the residue was purified by column chromatography on silica gel (eluent: cyclohexane/ethyl acetate 2:1). The product was triturated with petroleum ether/tert-butyl methyl ether (3:1) to yield 1.45 g (47%) of the title compound as yellow crystals.

Provenance & Evidence