Boc-L-Phe(4-NHFmoc)-OH is a protected amino acid derivative in which L-phenylalanine bears a para-substituted anilide side chain functionalized with an Fmoc-protected amino group at the 4-position. The molecule contains an N-terminal Boc protecting group, a free carboxyl group, and an additional Fmoc carbamate on the side-chain amino functionality, providing dual orthogonal protection for chemoselective transformations. In peptide and amino acid derivative synthesis, it functions as a building block that can support stepwise introduction of a phenylalanine residue while retaining the side-chain amino group in a protected, handle-bearing form for subsequent coupling, deprotection, and downstream conjugation or structure-activity studies.
CAT No: CP25174
CAS No:114346-31-5
Synonyms/Alias:114346-31-5;boc-4-(fmoc-amino)-l-phenylalanine;boc-l-(4-fmoc)aminophenylalanine;boc-p-amino-phe(fmoc)-oh;(S)-3-(4-((((9H-Fluoren-9-yl)methoxy)carbonyl)amino)phenyl)-2-((tert-butoxycarbonyl)amino)propanoicacid;boc-phe(4-nhfmoc)-oh;boc-l-phe(4-nh-fmoc);AC1MBSH7;boc-p(nh-fmoc)-l-phe-oh;SCHEMBL503172;CTK8C5720;boc-l-4-aminophenylalanine(fmoc);MolPort-000-151-687;ZKSJJSOHPQQZHC-VWLOTQADSA-N;Boc-L-(4-Fmoc)-aminophenylalanine;N-[(1,1-dimethylethoxy)carbonyl]-4-[[(9H-fluoren-9-ylmethoxy)carbonyl]amino]-L-Phenylalanine;ZINC2517126;2376AA;AKOS015896422;(s)-boc-(4-fmoc-amino)-phenylalanine;AJ-37030;AK117087;KB-211341;RT-011700;FT-0642785
Chemical Name:N-alpha-t-Butyloxycarbonyl-4-(9-fluorenylmethyloxycarbonyl)amino-L-phenylalanine
Boc-L-Phe(4-NHFmoc)-OH is a protected L-phenylalanine derivative bearing a Boc-protecting group on the amino terminus and an Fmoc-protected amino substituent on the para position of the aromatic ring. This dual-protection pattern provides orthogonal protection and controlled reactivity, enabling downstream peptide assembly while preserving the functionalized side-chain for later elaboration or selective deprotection. The aromatic side chain also supports common medicinal-chemistry and peptide-scaffold design workflows where phenylalanine-like residues are required with a handle for further functionalization.
1. Orthogonally Protected Peptide Building Block
Boc-L-Phe(4-NHFmoc)-OH is used as a specialty amino acid building block for peptide synthesis workflows that require a phenylalanine residue with a protected para-amino functionality. Researchers developing peptide libraries and complex peptide constructs rely on the Boc-protected backbone for compatibility with protected-amino-acid assembly strategies, while the Fmoc-protected side-chain amino group allows controlled downstream modification after peptide assembly. This format is particularly useful when the final peptide must retain a defined aromatic substitution pattern, such as for structure-activity relationship (SAR) studies or for generating peptide variants that differ only at the side-chain functionalization level.
2. Side-Chain Functionalization After Assembly
Boc-L-Phe(4-NHFmoc)-OH supports stepwise chemical diversification of peptide scaffolds by carrying a masked aromatic amine that can be selectively unmasked or transformed at a later stage. In chemical biology and peptide engineering settings, this enables the introduction of an aniline-derived functionality onto a phenylalanine-containing sequence without disturbing other protected groups during earlier coupling steps. The protected side-chain amino group is leveraged to prepare peptide conjugation-ready intermediates, to generate panels of analogs with different aromatic substituents, and to support downstream derivatization routes used in binding studies, receptor-ligand mapping, or assay development requiring defined side-chain chemistry.
3. Medicinal Chemistry Peptidomimetic Intermediates
Boc-L-Phe(4-NHFmoc)-OH is frequently selected for the preparation of peptidomimetic and medicinal-chemistry intermediates where an aniline-bearing aromatic motif is needed in a controlled, protected form. Medicinal chemistry groups use this reagent to construct protected fragments that can later be incorporated into larger synthetic sequences, including the assembly of peptide-like structures and constrained analogs. The combination of backbone protection and a protected para-amino substituent helps maintain synthetic control over chemoselectivity, allowing the aromatic amine functionality to be introduced or modified at a defined stage of the overall synthesis plan.
4. Protected Aromatic Amine Chemistry
Boc-L-Phe(4-NHFmoc)-OH is used to access protected aromatic amine chemistry within peptide-derived materials and specialty synthetic sequences. Polymer and biomaterials researchers, as well as peptide manufacturing teams, may employ this building block to introduce a protected para-amino group on an aromatic side chain that can be converted into reactive or further functional groups after the main scaffold is assembled. This approach is valuable when the target material or conjugate requires precise placement of an aniline-derived functionality while minimizing side reactions during earlier steps, supporting reproducible preparation of functionalized peptide segments and their downstream derivatives.
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