Fmoc-L-Tyr(tBu)-OSu is a protected amino acid derivative in which the L-tyrosine α-amino group is masked by the Fmoc (fluorenylmethyloxycarbonyl) protecting group and the phenolic side chain is protected as a tert-butyl ether, while the carboxyl functionality is converted to an N-hydroxysuccinimide (OSu) active ester. The molecule contains the Fmoc carbamate and an OSu ester that together create an activated carboxyl group for amide bond formation, with stereochemistry consistent with the L-configuration indicated in the name and a free phenolic hydroxyl not present due to tert-butyl protection. Fmoc-L-Tyr(tBu)-OSu is used in peptide synthesis and related coupling workflows as an activated tyrosine building block, supporting stepwise assembly where chemoselective handling of the carboxyl group and orthogonal protection of the phenolic side chain help control side reactions.
CAT No: CP25397
CAS No:155892-27-6
Synonyms/Alias:Fmoc-L-Tyr(tBu)-OSu;155892-27-6;AmbotzFAA6550;CTK8E9970;C32H32N2O7;6951AH;ZINC100238669;RT-013006;FT-0626513
Chemical Name:N-alpha-(9-Fluorenylmethyloxycarbonyl)-O-t-butyl-L-tyrosine succinimidyl ester
Fmoc-L-Tyr(tBu)-OSu is an Fmoc-protected L-tyrosine derivative bearing a tert-butyl-protected phenolic side chain and an activated N-succinimidyl ester (OSu) at the carboxyl group. The molecule combines a chiral amino acid backbone with an aromatic phenol protected as a tBu ether, while the OSu functionality enables acyl transfer under amide-forming conditions. The Fmoc group supports orthogonal protection strategies in stepwise peptide assembly, and the overall structure is designed to balance stability during synthesis with reactivity toward nucleophiles during coupling or labeling. The presence of a stereodefined L-configuration and a phenolic handle that can be unmasked after deprotection makes the compound suitable for constructing tyrosine-containing peptides, conjugates, and downstream synthetic intermediates in both research and manufacturing contexts.
1. Peptide Coupling Chemistry
Fmoc-L-Tyr(tBu)-OSu is used in peptide synthesis workflows where N-Fmoc strategy and carboxyl activation are required for efficient amide bond formation. The activated OSu ester reacts with amine nucleophiles to install the tyrosine residue while the Fmoc group preserves the amino functionality for controlled coupling cycles. The tBu-protected phenolic side chain prevents undesired O-acylation or side reactions during chain assembly, supporting clean incorporation of Tyr in protected form. Following peptide assembly, Fmoc removal and phenol deprotection can reveal a free tyrosine for further derivatization or for generating native Tyr-containing peptide frameworks. The structure therefore aligns with protected amino acid synthesis and peptide building block preparation for sequence-defined products.
2. Bioconjugation Labeling
Fmoc-L-Tyr(tBu)-OSu is applicable to bioconjugation chemistry where activated carboxylates are used to form stable amide linkages to biomolecule amines. The OSu ester can undergo acyl transfer to lysine side chains or N-terminal amines, while the Fmoc group can be managed as an orthogonal protecting group depending on the conjugation and downstream processing scheme. The tert-butyl-protected phenol helps maintain aromatic integrity during conjugation, reducing side reactions that could occur from free phenolic hydroxyl reactivity. Post-conjugation deprotection can generate a phenolic handle suitable for further functionalization, such as coupling to electrophiles or enabling analytical differentiation of tyrosine-bearing conjugates. This makes the compound relevant to chemical biology research intermediate preparation and amino acid derivatization routes that connect peptide-like building blocks to biomolecular targets.
3. Protected Amino Acid Intermediate
Fmoc-L-Tyr(tBu)-OSu supports protected amino acid intermediate development for manufacturing-scale peptide building blocks and fine chemical synthesis. The Fmoc-protected amino group and the tBu-protected tyrosine phenol provide orthogonal protection that can be selectively removed or transformed in a controlled sequence, enabling predictable downstream conversion to Fmoc-L-Tyr(tBu)-OH or peptide-ready derivatives. The OSu activation state functions as a carboxyl activation handle that can be used to generate amide-containing intermediates without requiring separate coupling reagent systems in certain synthetic designs. The stereochemically defined L-tyrosine core helps maintain configurational integrity through synthetic steps that rely on amino acid stereochemistry for product consistency. The compound's protected architecture and activated carboxyl group therefore align with process chemistry intermediate preparation and specialty chemical production of tyrosine-functional scaffolds.
4. Side-Chain Functionalization
Fmoc-L-Tyr(tBu)-OSu is suitable for side-chain functionalization strategies that leverage tyrosine's phenolic chemistry while controlling reactivity during synthesis. The tert-butyl-protected phenol suppresses unwanted oxidation or electrophilic side reactions during peptide coupling or conjugate formation, while the aromatic hydroxyl can be revealed after deprotection for subsequent derivatization. The OSu ester enables incorporation into amide-linked frameworks, allowing the phenolic group to be positioned for later transformations such as etherification, esterification, or electrophile-mediated coupling in tyrosine-containing constructs. The Fmoc group further supports stepwise assembly logic, enabling the same tyrosine residue to be introduced as a protected side-chain unit and later converted to a functional phenol-bearing product. This application category connects amino acid modification and peptidomimetic construction to downstream molecular diversification through controlled protection-group behavior.
5. Structure-Activity Relationship Studies
Fmoc-L-Tyr(tBu)-OSu can be employed in structure-activity relationship studies requiring defined incorporation of tyrosine residues into peptide analogs and SAR-focused libraries. The activated OSu ester supports rapid installation of the Tyr side chain into amide-linked scaffolds, while the Fmoc strategy supports parallel synthesis workflows where orthogonal deprotection steps are used to control which functional groups are exposed at each stage. The tBu-protected phenol helps maintain uniformity across library members by preventing premature side-chain reactivity, enabling consistent downstream phenol-unmasking and functional comparison. The stereodefined L-configuration supports reproducible recognition features in peptide-like molecules, which is often critical when evaluating how aromatic side chains influence binding or stability. The compound thereby serves as a chemically grounded reagent for amino acid derivatization and peptide science efforts that generate SAR-ready tyrosine-containing intermediates.
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