Compound A is a derivative of the carbohydrate perosamine, which is found in the antibioti...

Compound A is a derivative of the carbohydrate perosamine, which is found in the antibiotic perimycin. When A is treated with excess acetic anhydride in methanol, a mono-acyl derivative B (C9Hl7NO5) is obtained in 73% yield.

(a)   What is its structure? (Hint: Consider that methanol reacts with acetic anhydride.)

(b)   Explain the selectivity of this reaction.

(c)   What is the expected product if methanol is omitted and the reaction is conducted with excess acetic anhydride in pyridine?