Fmoc-D-Ser(Bzl)-OH

Fmoc-D-Ser(Bzl)-OH is an Fmoc-protected D-serine derivative bearing a benzyl-protected side-chain hydroxyl, forming a chiral amino acid building block with orthogonally protected functional groups. The fluorenylmethoxycarbonyl (Fmoc) group masks the α-amino functionality for controlled peptide coupling and can be removed under base-mediated conditions, while the benzyl (Bzl) ether on the serine side chain provides stability during standard amide bond formation and enables later side-chain deprotection. The molecule contains a free carboxylic acid for activation and coupling, and the stereogenic center at the serine α-carbon preserves D-configuration for stereochemically defined peptide and peptidomimetic architectures. The combination of an orthogonally protected hydroxyl and a base-labile N-protecting group makes the compound suitable as a protected amino acid synthesis intermediate and as a controlled-reactivity peptide building block for downstream functionalization.

1. Peptide Synthesis

Fmoc-D-Ser(Bzl)-OH is used in peptide synthesis workflows where orthogonally protected serine is required for reliable N-Fmoc chemistry and side-chain stability during coupling cycles. The Fmoc-protected α-amine supports standard peptide coupling strategies after activation of the carboxylic acid, while the benzyl-protected hydroxyl prevents premature side reactions such as uncontrolled O-acylation or cross-linking. Incorporation of the D-serine stereocenter enables stereochemically defined peptide sequences for backbone and side-chain recognition studies, including D-amino acid containing analogs. Post-assembly deprotection of the benzyl ether can generate a free serine hydroxyl for subsequent derivatization, enabling access to phosphoserine-like motifs, glycosylation handles, or hydroxyl-bearing peptidomimetics.

2. Side-Chain Functionalization

Fmoc-D-Ser(Bzl)-OH serves as a protected amino acid intermediate for side-chain functionalization strategies that require delayed exposure of the serine hydroxyl. The benzyl ether on the side chain functions as a protecting-group handle that can be removed to reveal a primary alcohol suitable for further conversion into esters, ethers, carbamates, or phosphorylated analogs under appropriate conditions. The D-configuration can be leveraged to tune conformational preferences and hydrogen-bonding patterns in peptide conjugates and peptidomimetics, while the Fmoc group supports stepwise synthetic sequencing. Downstream derivatization of the liberated hydroxyl enables construction of functional scaffolds for chemical biology research, including hydroxyl-reactive linkers and bioorthogonal precursor motifs.

3. Chemical Biology Conjugation

Fmoc-D-Ser(Bzl)-OH is applicable to chemical biology workflows that require controlled installation of serine-derived functional groups into peptide-based probes and conjugates. The protected hydroxyl and Fmoc-protected amine enable sequential assembly of peptide fragments where the serine side chain remains inert during fragment coupling, then becomes available for conjugation chemistry after orthogonal deprotection. The carboxylic acid functionality supports incorporation into amide-linked probe scaffolds, while the D-serine stereochemistry can be used to modulate protease stability and alter recognition in molecular interaction studies. Resulting serine-containing peptide conjugates can be used as building blocks for affinity probes, labeling reagents, and structured linkers in biomolecule modification programs.

4. Peptidomimetics And SAR Studies

Fmoc-D-Ser(Bzl)-OH supports peptidomimetic construction for structure-activity relationship studies where stereodefined serine residues and controlled side-chain reactivity are needed. The orthogonal protection pattern allows incorporation into analog libraries without side-chain interference during N-terminal protection management, while the benzyl ether provides a stable placeholder for later functional group unveiling or transformation. D-serine incorporation can be used to systematically vary backbone stereochemistry and hydrogen-bonding geometry, enabling SAR exploration of how stereochemistry and side-chain chemistry influence target binding or molecular recognition. Downstream conversion of the side-chain hydroxyl after assembly enables generation of hydroxyl-functional analogs, constrained variants, or modified serine surrogates used in medicinal chemistry and biochemical assay development.

5. Pharmaceutical Manufacturing Intermediates

Fmoc-D-Ser(Bzl)-OH can be employed in pharmaceutical manufacturing-oriented peptide intermediate preparation where reproducible, orthogonally protected amino acid building blocks are required for scalable synthesis planning. The Fmoc group provides a standardized N-protection strategy compatible with established peptide coupling and purification workflows, while the benzyl-protected serine hydroxyl helps maintain chemoselectivity during repeated coupling and deprotection steps. The free carboxylic acid enables activation and incorporation into peptide intermediates used for further processing into drug substance-related materials, including peptide fragments and protected intermediates for final assembly. The compound's defined stereochemistry and protection scheme make it suitable for process chemistry intermediate supply chains that prioritize controlled functional group exposure during manufacturing sequence design.

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