Acetic Anhydride → 2-Acetoxyethyl 9-(2,3-Dichlorophenyl)-1,1-dioxo-2,3,4,5,6,9-hexahydro-7-methylpyrido [2,3-f][1,4]thiazepine-8-carboxylate

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Reaction Conditions

Reaction Steps

2-Hydroxyethyl 4-t-butyloxycarbonyl-9-(2,3-dichlorophenyl)-1,1-dioxo-5a-hydroxy-2,3,4,5,5a,6,9,9a-octahydro-7-methylpyrido[2,3-f][1,4]thiazepine-8-carboxylate (0.500 g, 0.97 mmole) from Example 18, was dissolved in 5 mL of pyridine and 5mL of acetic anhydride, and stirred for 2 hours. The solvents were removed under reduced pressure, and the residue was slurried in 25 mL of ethyl acetate and cooled to 0° C., after which the mixture was saturated with gaseous HCl. After 90 minutes, the reaction was poured into 30 mL of 4N NaOH. The ethyl acetate layer was separated and dried with brine, and the aqueous layer was extracted with 2×30 mL of chloroform. The combined organic extracts were dried with sodium sulfate and evaporated, and the residue was chromatographed (2% methanol, 0.1% ammonia in chloroform, silica gel) to give the product as a white solid (0.351 g, 89% yield).

Provenance & Evidence