N-acetoxyphthalimide

Acetoxy-l-nonanoic add, 811 N-Acetoxyphthalimide, 9 21-Acetoxypregnane-3,ll,20-trione, 524 17a-Acetoxy-A -pregnene-3d-ol-20-one, 318 17a-Acetoxy-A -pregnenolone formate, 36-... 

N-Acetoxyphthalimide (2). The reagent is prepared by reaction of sodium N-hydroxy-phthalimide (which see) with acetyl chloride. It is recommended specifically - for N-acetylation of muramlc acid (1), since acetylation with acetic anhydride and pyridine gives products of intramolecular cyclization (lactams). Osawa and Jeanloz treated a solution of (1) in methanol at 0° with 2 equivalents of the reagent and 1 equivalent of triethylamine and let the mixture stand at room temperature for 20 hrs. 

After evaporation, the residue was extracted with water and the filtered solution adjusted to pH 3.5 with Araberlite IR 120 and extracted with ethyl acetate. The residual sirup crystallized spontaneously, and recrystallization from ethyl acetate-methanol afforded pure (3) in 70% yield. When the reaction was carried out with only 1 equivalent of N-acetoxyphthalimide, the product was a mixture of (1) and (3). 

Acetylation Acetic anhydride. N-Acetoxyphthalimide. 2- and 3-Acetoxypyridine. Acetyl chloride. N-Acetylimidazole. Boron trifluoride. Catalysts (see Acetic anhydride). Ketene. Magnesium. Methyl oxocarbonium hexafluoroantimonate. Perchloric acid. Phenyl acetate. Pyridine. Sodium acetate. Tetraelhylammonium acetate. p-Toluenesulfonic acid. Tri-n-hexylethyl ammonium hydroxide. 2,4,6-Triisopropylbenzenesulfonyl chloride. Trityl-sodium. Zinc chloride. 

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