Water → N-{2-[(9S)-2-methyl-8,9-dihydro-7H-cyclopenta[c]pyrazolo[1,5-a]pyridin-9-yl]ethyl}acetamide

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Reaction Conditions

Reaction Steps

A mixture of ethyl (9S)-9-{2-[(tert-butoxycarbonyl)amino]ethyl}-2-methyl-8,9-dihydro-7H-cyclopenta[c]pyrazolo[1,5-a]pyridine-1-carboxylate (140 mg, 0.361 mmol) in 12M hydrochloric acid (4 mL) was stirred at 100° C. for 3 days, and concentrated under reduced pressure. To a mixture of the residue and triethylamine (503 μL, 3.61 mmol) in tetrahydrofuran (3.6 mL) was added acetic anhydride (102 μL, 1.08 mmol) under ice-cooling, and the mixture was stirred at room temperature for 10 min. Water (50 μL) was added, and the solvent was evaporated under reduced pressure. The residue was purified by silica gel column chromatography (methanol/ethyl acetate=0/100→5/95) to give the title compound (69.7 mg, yield 75%, >99.9% ee). The enantiomer excess (ee) was measured by high performance liquid chromatography (column: CHIRALPAK AD-H mm ID×250 mm L, manufactured by Dicel Chemical Industries, Ltd.), mobile phase: hexane/ethanol=95/5, flow rate: 1.0 mL/min, column temperature: 30° C., sample concentration: 0.5 mg/mL (hexane/ethanol=95/5), injection volume: 10 μL).

Provenance & Evidence