I performed a boc deprotection via 25% TFA/DCM (1 hr) without any workup, which should yield TFA salt as a product. My compound also had a TBDMS group on it. But when I took an NMR, the amine peak is present TBS hydrogen peaks are not present. Is it possible that TBS was cleaved?
TBDMS protective group, especially on primary hydroxyls can certainly be cleaved in acidic conditions. It depends on the structure of your intermediate, as well as on the reaction conditions, but 25% TFA in dichloromethane makes it a pretty harsh media, so I will not be entirely surprised if it happened in your case.
As Vladimir Khlebnikov pointed out, silyl protecting groups can be removed with acid. For example, 1 equivalent of camphor sulfonic acid at room temperature in MeOH will cleave a primary TBS group in ten minutes. Considering its pKa is 1.2, and TFA's is 0.52, TFA is more than 5 times more acidic, so cleavage of your silyl protecting group is very likely
Muhammad M. Khalifa Vladimir Khlebnikov Thank you for your replies. What process can I use to deprotect boc in this case? I am currently trying with ZnBr2 but the reaction takes a long time.
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