Fmoc-trans-4-hydroxy-L-proline is an Fmoc-protected, trans-configured amino acid derivative based on L-proline, featuring a pyrrolidine ring bearing a 4-hydroxy substituent that provides a secondary alcohol side-chain functionality. The molecule contains an Fmoc carbamate protecting group on the amino functionality and retains a free carboxyl group, with the trans stereochemical relationship indicated between the ring and the substituent framework as specified by the product name. In peptide chemistry and solid-phase peptide synthesis workflows, the Fmoc-protected amino acid is used as a building block to introduce hydroxyproline-containing residues for structure-activity studies, protein engineering constructs, and the preparation of more complex peptide derivatives.
Fmoc-trans-4-hydroxy-L-proline is an N-(9H-fluoren-9-ylmethoxycarbonyl) protected trans-4-hydroxy-L-proline derivative that preserves the cyclic proline backbone and presents a stereodefined hydroxyl-bearing side chain at C4. The trans relationship between the ring substituent and the stereocenter, together with the rigid pyrrolidine ring, supports predictable conformational behavior during peptide assembly and subsequent derivatization. The Fmoc carbamate masks the α-amino functionality for orthogonal peptide coupling, while the free 4-hydroxyl group participates in hydrogen bonding and can be selectively protected, activated, or converted into leaving groups for downstream transformations. The compound functions as a chiral amino acid building block and intermediate for preparing hydroxyproline-containing peptides, peptidomimetics, and hydroxyl-functionalized scaffolds with stereochemical control.
1. Peptide Synthesis
Fmoc-trans-4-hydroxy-L-proline serves as a protected amino acid building block for solid-phase peptide synthesis and solution-phase peptide coupling where hydroxyproline residues are required. The Fmoc-protected nitrogen enables standard peptide bond formation while maintaining the trans stereochemistry of the ring-substituted proline, which can influence local turn formation and backbone conformations. The side-chain 4-hydroxyl group can remain free for hydrogen-bonding interactions in the assembled peptide or be temporarily protected to prevent side reactions during coupling and deprotection cycles. The resulting hydroxyproline-containing peptide products are applicable to peptide science workflows, including scaffold generation, conformational studies, and synthetic access to collagen-mimetic motifs.
2. Peptidomimetics And SAR Studies
Fmoc-trans-4-hydroxy-L-proline is suitable for peptidomimetic construction and structure-activity relationship studies where hydroxyl functionality and proline ring rigidity are used to tune molecular recognition. The stereodefined trans-4-hydroxy substitution and the cyclic secondary amine framework can be carried into analogs that probe how side-chain hydrogen bonding and constrained geometry affect binding or selectivity in assay-driven design. The Fmoc group supports iterative assembly into longer analogs, while the 4-hydroxyl can be converted into ether, ester, or activated derivatives to generate a controlled series of functional analogs. Hydroxyproline-bearing analogs prepared from this chiral intermediate can feed medicinal chemistry and SAR exploration pipelines that rely on systematic functional group variation.
3. Side-Chain Functionalization
Fmoc-trans-4-hydroxy-L-proline supports amino acid derivatization strategies focused on the 4-hydroxyl side chain while preserving the protected amine for orthogonal chemistry. The free hydroxyl can be selectively protected (for example, as an acyl or silyl ether) or transformed into electrophilic intermediates for subsequent substitution, enabling access to O-alkylated, O-acylated, or leaving-group-containing derivatives. The trans stereocenter and rigid proline ring help maintain stereochemical integrity through multi-step functionalization sequences used to build hydroxyl-functionalized chiral fragments. Downstream derivatives prepared from this intermediate can be used to generate modified peptide building blocks, stereodefined small-molecule fragments, and functionalized chiral intermediates for fine chemical synthesis.
4. Chemical Biology Labeling
Fmoc-trans-4-hydroxy-L-proline can be applied in chemical biology workflows that require incorporation of hydroxyproline into peptide probes and biomolecule-interacting constructs. The hydroxyl-bearing side chain enables conjugation handles through derivatization to linkers, affinity tags, or reporter-compatible functionalities, while the proline scaffold supports incorporation into peptide sequences that maintain defined conformational features. The Fmoc protection strategy allows controlled release of the amino functionality during peptide assembly, supporting preparation of labeled peptides with defined stereochemistry at the hydroxyproline residue. Hydroxyproline-containing probes derived from this compound can be utilized for studying biomolecular interactions, monitoring binding conformations, and generating chemically defined reagents for analytical and research applications.
5. Pharmaceutical Manufacturing Intermediate
Fmoc-trans-4-hydroxy-L-proline is suitable as a chiral intermediate for industrial peptide manufacturing routes that require hydroxyproline-containing sequences or hydroxyproline-derived fragments. The Fmoc carbamate provides a robust, industry-compatible protecting-group strategy for amino functionality during peptide coupling and purification steps, while the trans-4-hydroxyl group can be managed through selective protection to minimize undesired side reactions. The compound's stereochemical fidelity supports consistent quality of hydroxyproline incorporation across batch-to-batch peptide synthesis, which is relevant for process chemistry and downstream intermediate formation. Hydroxyproline-containing intermediates generated from this material can be carried into further synthetic transformations to furnish peptide ingredients, process intermediates, and stereodefined building blocks used in specialty chemical production.
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