The enhancement of signal sensitivity and quantification of low‐abundance proteins is of great importance in proteomic analysis. The preparation of 2‐methoxy‐4,5‐dihydro‐1H‐imidazole (MeO‐DHIM) derivatives was accomplished by one‐step synthesis of O‐methyl‐isourea. The signalenhancement induced by these attached moieties increases in an order of compound 1 ≈︁ 4 < 2 < 5 ≈︁ 6 < 3 in MALDI mass spectrometry