I'm learning about the Zuckermann approach to combinatorial chemistry in my MedChem lecture. My textbook claims that the Fmoc protecting group is base-labile while the Moz protecting groups is acid-labile. Please see image below.

enter image description here

Both protecting groups have the same exact structure that is bonded to the amine (methoxycarbonyl) so should be equally reactive to either an acid or a base. How come this isn't true?

In other words, why does hydroxide succesfully attack the carbonyl to liberate the amine in Fmoc, but not in Moz. Conversely, why does hydronium protonate the amine to create a good leaving group for the resultant water molecule to attack Moz and kick it (the amine) off, but Fmoc is not open to this pathway? (NOTE: These are my assumptions for how the mechanisms work. They could be (and most likely are) wrong.)

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    $\begingroup$ Are you able to draw the mechanisms? $\endgroup$ – orthocresol Oct 13 '16 at 17:18
  • $\begingroup$ The mechanisms are really straightfoward. Just a simple acid or base catalyzed ester hydrolysis $\endgroup$ – Nova Oct 15 '16 at 0:51
  • $\begingroup$ You are wrong about the mechanism of FMOC deprotection. It proceeds by deprotonation of the doubly benzylic methine, followed by CO2 loss. $\endgroup$ – Waylander Dec 17 '17 at 21:44

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