Fmoc-Leu-OH

Fmoc-Leu-OH is the preferred N‑α‑protected form of L‑leucine for solid‑phase peptide synthesis, widely employed as a fundamental building block in both manual and automated SPPS protocols. The Fmoc group on Fmoc-Leu-OH provides mild, orthogonal protection that can be selectively removed under basic conditions without disturbing acid‑labile side‑chain protecting groups, making Fmoc-Leu-OH the reagent of choice for constructing complex, long‑chain, and aggregation‑prone peptides. As a hydrophobic amino acid derivative, Fmoc-Leu-OH is routinely incorporated into membrane‑interacting peptides, drug‑targeting conjugates, and therapeutic peptide candidates. The compound also serves as a research tool in PPARγ ligand studies, where it has been shown to reduce osteoclast differentiation through PPARγ activation. Beyond its core application in peptide synthesis, Fmoc-Leu-OH has also been studied for its self‑assembling properties under varying concentration and temperature conditions.

Product Parameters

Synthetic Route

Dissolve 1.05 grams (0.008 moles) of L-leucine solid in a 10% sodium carbonate solution, stirring to ensure complete dissolution of glycine solid. At 20–30°C, add dropwise a solution of 9-fluoromethoxycarbonyl chloride (2.10 grams, 0.008 moles) dissolved in toluene (2–205 mL) over 30–60 minutes until completion. Continue stirring at 20–30°C for 1–8 hours, then dilute with 30–200 mL of water. Extract the excess 9-fluoromethoxycarbonyl chloride using n-butyl acetate (80 mL). The resulting aqueous phase is acidified with concentrated hydrochloric acid to pH 0.5–3.5 and extracted again with n-butyl acetate (80 mL); the oil phase is washed with water to remove hydrochloric acid, concentrated to eliminate the n-butyl acetate solvent, yielding white crystals. Upon filtration and drying, the product Nα-9-fluoromethoxycarbonyl-L-leucine is obtained in 2.46 grams, with a yield of 87.0% and a melting point of 151–152°C.

FAQ

Q1: What is the difference between Fmoc-Leu-OH and Boc‑Leu‑OH?

A: Fmoc-Leu-OH uses the fluorenylmethyloxycarbonyl (Fmoc) protecting group, which is removed under mild basic conditions (20% piperidine in DMF). Boc‑Leu‑OH uses the tert‑butyloxycarbonyl (Boc) group, which is removed under acidic conditions (TFA). For solid‑phase peptide synthesis (SPPS), Fmoc/tBu is the dominant methodology due to its orthogonal protection strategy and mild deprotection conditions that preserve acid‑labile side‑chain protecting groups.

Q2: Is Fmoc-Leu-OH the same as L‑leucine?

A: No. Fmoc-Leu-OH is the Fmoc‑protected derivative of L‑leucine. The Fmoc group is attached to the α‑amino group of L‑leucine, while the carboxylic acid terminus remains free for peptide bond formation. L‑leucine itself has no protecting group and is fully water‑soluble; Fmoc-Leu-OH is soluble in organic solvents (DMF, DMSO) and is not recommended for direct use in aqueous reaction systems.

Quality Assurance at Cosperpharm

Each batch undergoes:

lGas chromatography (GC) – purity ≥97.0%

lNon‑aqueous titration – purity ≥97.0%

lRefractive index – confirmatory analysis

l¹H NMR – structural verification

lAppearance – colorless to light yellow to light orange clear liquid

A comprehensive COA, MSDS (with full GHS information), and certificate of origin accompany every shipment.

Contact Us

Looking for high‑purity Fmoc-Leu-OH for your next peptide synthesis campaign, process development project, or quality control workflow? Reach out to the Cosperpharm team—we will respond with a detailed quote, product specifications, and shipping timelines tailored to your requirements.