Building block with side protection orthogonal to Fmoc/tBu strategy. Can be used for side specific derivatization, for example for TFA mediated in situ cyclization, which is taking advantage of intermediate aspartamide formation. References: A Tandem In Situ Peptide Cyclization through Trifluoroacetic Acid Cleavage; Koushik Chandra, Tapta Kanchan Roy, Deborah E. Shalev, Abraham Loyter, Chaim Gilon, R. Benny Gerber, and Assaf Friedler; Angew. Chem. Int. Ed. 2014; 53: 9450-9455. DOI: 10.1002/anie.201402789. Luca Monfregola, Marilisa Leone, Enrica Calce, Stefania De Luca; Postsynthetic Modification of Peptides via Chemoselective N-Alkylation of Their Side Chains; Org. Lett. 2012; 14(7): 1664-1667; doi 10.1021/ol300437w. Stefania De Luca, Raffaella Della Moglie, Antonia De Capua, Giancarlo Morelli; New synthetic strategy for o-NBS protected amino acids and their use in synthesis of mono-benzylated peptides; Tetrahedron Lett. 2005; 46: 6637-6640; doi:10.1016/j.tetlet.2005.07.154. Luca Monfregola, Stefania De Luca; Synthetic strategy for side chain mono-N-alkylation of Fmoc-amino acids promoted by molecular sieves; Amino Acids 2001; 41(4): 981-990; doi 10.1007/s00726-010-0798-6.
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