*2.1. Chemicals*

All amino acid derivatives and Wang resin were purchased from Iris Biotech GmbH (Marktredwitz, Germany), whereas reagents for coupling and cleavage (*N,N*0 -diisopropylcarbodiimide (DIC), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1-hydroxybenzotriazole hydrate (HOBt), 4-(dimethylamino)pyridine (DMAP), triisopropylsilane (TIS), trifluoroacetic acid (TFA)) and ninhydrin were delivered by Sigma-Aldrich Kft. (Budapest, Hungary). Aminooxyacetic acid (Aoa) and methoxyamine were TCI (Tokyo, Japan) products. The solvents (dichloromethane (DCM), *N,N*-dimethylformamide (DMF), acetonitrile (CH3CN)) for synthesis and purification were obtained from Reanal (Budapest, Hungary) or VWR International Kft. (Debrecen, Hungary). Daunomycin (Dau) was donated from IVAX (Budapest, Hungary).
