2,4-Dimethoxybenzyl, acid-labile carboxamide protecting group used for the reversible backbone modification of peptides. Incorporation of Fmoc-Dmb amino acids  or dipeptides (Fmoc-Xaa-DmbYaa-OH) during Fmoc-SPPS prevents aggregation and thus facilitates the elongation of the peptide. Facilitation of cyclization reactions and prevention of aspartimide formation are further applications of Dmb backbone protection.

Unlike Hmb amino acids/dipeptides, Dmb derivatives cannot form benzo-oxazepinones during activation.