The use of Fmoc as a temporary protecting group for amine at the N-terminus in SPPS is very widespread for Fmoc/tBu approach, because its removal with piperidine solution does not disturb the acid-labile linker between the peptide and the resin. A typical SPPS Fmoc deprotection is performed with a solution of 20% piperidine in N,N-dimethylformamide (DMF).
Common deprotection cocktails for Fmoc during SPPS:
* 20% piperidine in DMF (Fmoc group has an approximate half life of 6 seconds in this solution)
* 5% piperazine, 1% DBU and 1% formic acid in DMF. This method avoids the use of strictly controlled piperidine. No side product was observed for a peptide with 9 residues synthesized with this method.