α-Allyl esters are of special interest, because they are a useful tool for the on-resin synthesis of head-to-tail cyclic peptides, side-chain lactam peptides, glyco- and sulfo-peptides, and branched peptides. Allyl esters are cleaved quantitatively under mild conditions using Pd(0). These conditions are compatible with Fmoc- and Boc-SPPS. Fmoc-Glu-OAll is a versatile educt for the synthesis of N-modified glutamines.
Due to the lack of steric hindrance of the allyl group, prolonged treatment with harsher Fmoc cleavage agents or even piperidine may induce side-reactions as glutarimide formation, as observed by Zhu and Marchant.