Acetic Anhydride → Ethyl (3R,4R,5S)-4-acetamido-5-azido-3-(1-ethylpropoxy)-1-cyclohexene-1-carboxylate

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Reaction Steps

To a solution of 118.5 mg of 28 and 1.0 mL of EtOAc in a 5.0 mL round-bottom flask equipped with a magnetic stirrer and an inert gas supply was added 1.0 mL of aqueous 1 M NaHCO3. To the stirred mixture was added 45.4 μL of acetic anhydride and the mixture was stirred for 1 h at RT. The organic phase was separated and dried (Na2SO4, 1 g), filtered and the filter cake was washed with 2.0 mL EtOAc. The combined filtrates were evaporated at 40° C./240 to 10 mbar to afford 139 mg crude product as beige solid. The solid was suspended in 1.40 mL of n-hexane and 0.70 mL tert-butyl methyl ether, stirred for one h at RT, cooled to 0-5° C. and stirred for 2 h at 0-5° C. The suspension was filtered and the filter cake was washed with total 0.70 mL of a pre-cooled (0-5° C.) mixture of n-hexane and tert-butyl methyl ether (2/1). The filter cake was dried at 45° C./9 mbar to afford 94 mg of 30 as white crystals.

Provenance & Evidence