Hydrochloric Acid → tert-Butyl 3-methyl 4-[3-(6-cyano-3-oxo-2,3-dihydro-4H-1,4-benzoxazin-4-yl)propyl]piperidine-1,3-dicarboxylate

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Reaction Steps

A solution of 3-oxo-3,4-dihydro-2H-1,4-benzoxazine-6-carbonitrile (Intermediate 60) (265 mg, 1.53 mmol) in dry dimethylformamide (DMF) (5 mL) was treated at 0° C. with sodium hydride (105 mg, 60% in oil, 2.63 mmol) and then stirred for 30 minutes at room temperature. A solution of 1-tert-butyl 3-methyl 4-{3-[(methylsulfonyl)oxy]propyl}piperidine-1,3-dicarboxylate in DMF (Intermediate 132, 0.31 mmol/mL, 5 mL, 1.53 mmol) was then added and the resulting mixture was stirred at room temperature for 96 hours. The reaction was diluted with ethyl acetate and water. The aqueous layer was adjusted to pH3 with 1N HCl. The layers were separated. The aqueous phase was extracted once with ethyl acetate. The combined organic phases were washed four times with water, dried over magnesium sulfate and evaporated at reduced pressure. Chromatography on silica gel with (10-35%) acetone in hexanes gave 445 mg (64%) of the product as a white semi-solid (as a mixture of diastereomers).

Provenance & Evidence