Fmoc-4,5-dehydro-Leu-OH is an Fmoc-protected amino acid derivative featuring a leucine-derived backbone bearing a 4,5-dehydro (alkene) modification in the side-chain region, classifying it as a non-natural, conformationally restricted amino acid building block for peptide synthesis. The molecule contains an Fmoc carbamate protecting group on the α-amino functionality and a free carboxylic acid for coupling, with the side-chain double bond providing altered steric and electronic characteristics compared with saturated leucine. In synthesis and chemical biology workflows, it is used as a precursor for incorporating the dehydro-leucine residue into peptides or peptide analogues via stepwise assembly, supporting structure-activity studies and conformational probing through the unsaturation-induced geometry of the side chain.
CAT No: CP27558
CAS No:87720-55-6
Synonyms/Alias:fmoc-4,5-dehydro-l-leucine;87720-55-6;(S)-2-((((9H-Fluoren-9-yl)methoxy)carbonyl)amino)-4-methylpent-4-enoic acid;MFCD00237651;Fmoc-4,5-dehydro-Leu-OH;(2S)-2-[[(9H-Fluoren-9-ylmethoxy)carbonyl]amino]-4-methyl-4-pentenoic acid;FMOC-4,5-dehydro-L-Leu-OH;(2S)-2-(9H-fluoren-9-ylmethoxycarbonylamino)-4-methylpent-4-enoic acid;Fmoc-4,5-dehyro-L-Leu-OH;Fmoc-(S)-2-methallylglycine;SCHEMBL14570616;DTXSID20427199;(2S)-2-{[(9H-fluoren-9-ylmethoxy)carbonyl]amino}-4-methylpent-4-enoic acid;AKOS016344241;FD21882;FF47792;DS-11793;DS-018156;CS-0101044;EN300-7313261;(2S)-2-({[(9H-fluoren-9-yl)methoxy]carbonyl}amino)-4-methylpent-4-enoic acid;(S)-2-((((9H-Fluoren-9-yl)methoxy)carbonyl)amino)-4-methylpent-4-enoic?acid;
Fmoc-4,5-dehydro-Leu-OH is an Fmoc-protected, chiral leucine-derived amino acid featuring a 4,5-dehydro (alkene) motif in the side-chain region relative to the saturated Leu framework. The molecule contains a carbamate-protected alpha-amino group (Fmoc), a free carboxylic acid for coupling, and a defined stereocenter at the alpha position that governs peptide backbone incorporation. The unsaturation embedded in the side chain can participate in chemoselective transformations while remaining compatible with standard peptide synthesis conditions when appropriately protected and handled. As a peptide building block and chiral synthetic intermediate, it can be used to introduce constrained, unsaturated hydrophobic character into peptides and peptidomimetics for structure-function interrogation.
1. Peptide Synthesis
Fmoc-4,5-dehydro-Leu-OH is used in solid-phase peptide synthesis to install an unsaturated leucine analog at a defined position within a growing chain. The Fmoc carbamate enables orthogonal N-protection, while the free C-terminal carboxylic acid supports amide bond formation via common peptide coupling chemistries. The 4,5-dehydro side-chain alkene can be retained through assembly steps and later used for post-coupling functionalization or conformational tuning. Resulting unsaturated peptide scaffolds can be applied to mapping sequence effects, generating constrained analog series, and producing peptide building blocks for downstream chemical biology workflows.
2. Peptidomimetics And SAR Studies
Fmoc-4,5-dehydro-Leu-OH is suitable for peptidomimetic construction in medicinal chemistry research where side-chain unsaturation is used to modulate sterics, polarity distribution, and local conformational preferences. The alpha stereochemistry inherited from the leucine scaffold supports stereochemically consistent incorporation into peptide-like frameworks, while the alkene at the 4,5-position provides a handle for subsequent derivatization. The Fmoc-protected amine and carboxylic acid facilitate controlled incorporation into analog libraries, enabling structure-activity relationship studies that compare saturated versus dehydro variants. Downstream functionalization of the alkene can generate additional analogs for SAR expansion, including conjugation-ready or reactive motifs while maintaining a peptide-compatible core.
3. Side-Chain Functionalization
Fmoc-4,5-dehydro-Leu-OH enables side-chain functionalization strategies that leverage the chemically addressable alkene within the dehydro leucine framework. The presence of an Fmoc-protected nitrogen allows the compound to be handled as a stable amino acid derivative during synthesis, with deprotection and coupling steps providing access to peptide contexts where the alkene remains available. The unsaturation can be carried into peptide intermediates and then transformed into saturated or functionalized derivatives through chemoselective post-assembly modifications, supporting creation of alkenyl-to-functional group conversion products. Such workflows support generation of chemically diverse amino acid derivatives, intermediate building blocks for fine chemical synthesis, and functionalized peptide analogs for biochemical probing.
4. Chemical Biology Conjugation
Fmoc-4,5-dehydro-Leu-OH supports chemical biology applications that require incorporation of a reactive amino acid residue into peptides for later conjugation. The Fmoc-protected amine and carboxylic acid allow assembly of conjugation-ready peptide constructs, while the side-chain alkene can serve as a functional handle for subsequent attachment of labels, probes, or affinity tags. The defined stereochemistry helps maintain consistent recognition properties when the dehydro residue is positioned within a binding or interaction motif. Resulting labeled or modified peptide reagents can be used for biochemical investigations of molecular interactions, enabling controlled generation of conjugation intermediates and structured probe libraries.
5. Process Chemistry Intermediate
Fmoc-4,5-dehydro-Leu-OH is relevant to process chemistry and specialty chemical production as a protected amino acid intermediate designed for scalable peptide building block manufacturing. The orthogonal protection pattern, combining an Fmoc-protected amine with a free carboxylic acid, supports predictable downstream coupling operations and controlled deprotection logic in manufacturing workflows. The alkene-containing side chain introduces a functional group that can be preserved during assembly and later transformed, enabling route design for subsequent derivative manufacture. The compound's chiral amino acid identity and peptide-compatible functionality make it suitable for producing dehydro-leucine-containing peptides and peptidomimetic intermediates used across research-grade and industrial fine chemical supply chains.
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