Is the acetyl protecting group cleavable with ammonia?

I read in several sources that one can cleave an acetyl protecting group attached to an amine (thus an amide!) with gaseous ammonia. I can't imagine that a nucleophilic attack by ammonia at the carbonyl group would cleave the acetyl group and release the amine. Is this possible? I find no evidence for this during my research. I would be very grateful for any advice.




In general N-acetyl takes a bit of shifting and NH3 is not strong enough (it will readily cleave O-Acetyl). Standard conditions are refluxing 1N HCl, heating with hydrazine, KOH in refluxing EtOH/ethylene glycol. 
If you are struggling to cleave RNHAc then forming RN(Ac)BOC with BOC2O/DMAP/MeCN followed by reaction with hydrazine can be effective. 


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