Fmoc-L-Pro(4-OBzl)-OH is an Fmoc-protected L-proline derivative bearing a 4-O-benzyl substituent on the proline side chain, classifying it as a protected amino acid suitable for peptide building blocks. The molecule contains an Fmoc carbamate protecting the α-amino group, a free carboxylic acid at the α-position, and a benzyl ether (OBzl) that masks the side-chain hydroxyl functionality while maintaining the cyclic proline backbone. In synthetic peptide chemistry, it is employed as a stepwise incorporation unit in protected amino acid strategies to control chemoselectivity and to introduce a proline residue with a protected hydroxyl side chain for subsequent peptide assembly and downstream functionalization.
CAT No: CP25472
CAS No:174800-02-3
Synonyms/Alias:174800-02-3;(2S,4R)-1-(((9H-Fluoren-9-yl)methoxy)carbonyl)-4-(benzyloxy)pyrrolidine-2-carboxylicacid;fmoc-hyp(bzl)-oh;Fmoc-O-Benzyl-L-4-hydroxyproline;AmbotzFAA1790;SCHEMBL5963754;CTK8B8731;MolPort-008-267-752;ANW-61137;ZINC15721633;AJ-67831;AK-59973;KB-206712;RT-004535;FT-0686514;ST24034142;Z5690
Chemical Name:(2S,4R)-N-alpha-(9-Fluorenylmethyloxycarbonyl)-4-oxybenzyl-L-proline
Fmoc-L-Pro(4-OBzl)-OH is an Fmoc-protected L-proline derivative bearing a benzyl-protected hydroxyl group at the 4-position of the pyrrolidine ring, giving a chiral amino acid building block with a defined stereochemical framework. The molecule contains an N-(9H-fluoren-9-ylmethoxycarbonyl) protecting group on the amino functionality and a carboxylic acid for peptide coupling, while the side-chain hydroxyl is masked as a benzyl ether to control chemoselectivity during synthesis. The benzyloxyl substituent introduces an aromatic, hydrophobic handle and a latent alcohol functionality that can be revealed by hydrogenolysis or alternative deprotection strategies. The combination of a rigid proline scaffold and an orthogonally protected side-chain alcohol supports stereochemically consistent incorporation into peptide sequences and downstream derivatization of the liberated hydroxyl.
1. Peptide Synthesis
Fmoc-L-Pro(4-OBzl)-OH is used in peptide building workflows where Fmoc chemistry enables controlled N-terminal protection and stepwise amide bond formation. The Fmoc-protected amino group and free carboxylic acid support standard peptide coupling while the 4-OBzl side-chain benzyl ether maintains the ring hydroxyl in a protected state during chain assembly. The proline ring constrains backbone conformation, and the benzyl-protected hydroxyl provides a protected functional handle for later side-chain modification after deprotection. Incorporation of this chiral, side-chain-functionalized proline supports synthesis of peptides and peptidomimetics that require preserved stereochemistry and orthogonal functional-group management for sequence diversification.
2. Side-Chain Functionalization
Fmoc-L-Pro(4-OBzl)-OH serves as a side-chain functionalization intermediate for introducing a masked alcohol within a proline-containing scaffold. The benzyl ether at the 4-position protects the hydroxyl from undesired acylation or coupling side reactions, while the aromatic benzyl group enables predictable deprotection to regenerate the free secondary alcohol. The liberated hydroxyl can then participate in further transformations such as esterification, ether formation, or derivatization to generate hydroxyl-bearing analogs for structure-activity relationship studies. Downstream, the compound's controlled release of the side-chain alcohol supports iterative chemical modification of peptide analogs and synthetic fragments derived from amino acid chemistry.
3. Peptidomimetics And SAR Studies
Fmoc-L-Pro(4-OBzl)-OH is applied in peptidomimetic and SAR-oriented library synthesis where a conformationally restricted proline unit and a functional side-chain are required for molecular recognition tuning. The rigid proline backbone provides stereodefined geometry for amide-linked scaffolds, while the 4-OBzl group allows the side-chain hydroxyl to remain protected during synthesis of analog series. After deprotection, the resulting hydroxyl-bearing proline motif can be used to modulate polarity, hydrogen-bonding capacity, and steric profile in analogs designed for binding studies. The compound's compatibility with protected amino acid synthesis and orthogonal deprotection strategies supports generation of chemically consistent SAR sets for mechanistic and recognition-focused research.
4. Chemical Biology Probes
Fmoc-L-Pro(4-OBzl)-OH is suitable for chemical biology workflows that require incorporation of an alcohol-bearing proline motif into labeled peptides or reactive probes. The Fmoc-protected amine enables reliable peptide coupling to introduce the chiral residue at defined positions, while the benzyl-protected hydroxyl prevents premature conjugation during probe assembly. Deprotection can reveal an alcohol handle for subsequent attachment of linkers, affinity tags, or reporter groups through etherification or esterification chemistry. The resulting labeled or functionalized peptide constructs can function as molecular tools for studying protein interactions, substrate recognition, or pathway-specific binding where defined stereochemistry and controlled functional-group placement are critical.
5. Pharmaceutical Intermediate Preparation
Fmoc-L-Pro(4-OBzl)-OH can be employed as a chiral intermediate in manufacturing-oriented fine chemical synthesis routes that require protected amino acid fragments for peptide-derived or peptide-like ingredients. The presence of an Fmoc-protected amine and a carboxylic acid supports downstream conversion into activated coupling partners or direct incorporation into protected sequences under controlled conditions. The benzyl ether at the 4-position provides a robust protecting-group strategy for managing a reactive secondary alcohol during intermediate isolation and multi-step synthesis. Industrially relevant downstream utility includes preparation of stereodefined proline-containing intermediates used for further functional-group transformations, enabling consistent material generation for peptide-based process development and specialty chemical production.
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