Fluorenylmethyloxycarbonyl protecting group

Upon deprotection, Fmoc yields a byproduct (Dibenzofulvene) that can be monitored by UV spectroscopy, allowing for efficient reaction tracking.

[1] Because the fluorenyl group is highly fluorescent, certain UV-inactive compounds may be reacted to give the Fmoc derivatives, suitable for analysis by reversed phase HPLC.

Piperidine is usually preferred for Fmoc group removal as it forms a stable adduct with the dibenzofulvene byproduct, preventing it from reacting with the substrate.

[5][6] The use of Fmoc as a temporary protecting group for amine at the N-terminus in solid phase synthesis is very widespread for Fmoc/tBu approach, because its removal with piperidine does not disturb the acid-labile linker between the peptide and the resin.

[7] A typical SPPS Fmoc deprotection is performed with a solution of 20% piperidine in N,N-dimethylformamide (DMF).