Piperidine is a cyclic organic compound containing a six-membered ring with a nitrogen atom. It is frequently used in peptide synthesis as a base and as a protective group for amino acids.

Piperidine can be used to deprotect Fmoc (9-fluorenylmethoxycarbonyl) groups, which are often used in solid phase peptide synthesis. Piperidine is a highly reactive base that can catalyse the formation of peptide bonds. It is commonly used in the coupling stage of peptide synthesis to activate carboxylic acids and promote peptide bond formation. Piperidine can also be used to cleave esters and other protecting groups from amino acids during peptide synthesis.