Boc-pGlu-OEt

Boc-pGlu-OEt is a versatile protected amino acid building block designed for the introduction of pyroglutamic acid residues into peptide sequences. The Boc protecting group in Boc-pGlu-OEt safeguards the ring nitrogen during peptide chain assembly, while the ethyl ester protects the carboxylic acid. As a conformationally constrained pyroglutamate derivative, Boc-pGlu-OEt is particularly valuable for synthesizing peptides where structural rigidity is desired. Whether used for N-terminal pyroglutamylation in Boc-strategy SPPS or as a chiral building block in asymmetric synthesis, Boc-pGlu-OEt delivers the purity and consistency that demanding synthetic applications require.

Product Parameters

Synthetic Route

＋→

 Synthesis of Boc-D-Ethyl p-Aspartate: The title compound was prepared using conventional methods or the following optimized procedure. First, L-ethyl p-aspartate was subjected to N-protection in dichloromethane with diisobutyl carbonate (Boc₂O) in the presence of a catalytic amount of DMAP, yielding N-Boc-L-ethyl p-aspartate. This compound was then dissolved in toluene and treated with lithium triethyl borohydride (LiEt₃BH) at –78°C for carbonyl reduction. After completion of the reaction, 2,6-dimethylpyridine (lutidine) and a catalytic amount of DMAP were added, followed by gradual addition of trifluoroacetic anhydride (TFAA) for dehydration to obtain 4,5-dehydroproline ethyl ester. Finally, the target product, Boc-D-ethyl p-aspartate, was obtained via cyclopropanation using Et₂Zn and ClCH₂I in 1,2-dichloroethane at –15°C. Detailed steps for synthesizing 4,5-dehydro-L-proline ethyl ester are as follows: L-ethyl p-aspartate (200 g, 1.27 mol) was dissolved in 1.2 L of dichloromethane, followed by sequential addition of diisobutyl carbonate (297 g, 1.36 mol) and a catalytic amount of DMAP (1.55 g, 0.013 mol). The mixture was allowed to react at room temperature for 6 hours. Upon completion, the reaction mixture was quenched with saturated saline solution; the organic phase was dried with anhydrous Na₂SO₄ and filtered through a short silica gel column, yielding 323 g (100%) of N-Boc-L-ethyl p-aspartate. Dissolve N-Boc-L-glutaryl ethyl ester (160 g, 0.62 mol) in 1 L of toluene, cool to –78 °C, and slowly add lithium triethyl borohydride (666 mL, 1.0 M THF solution) over a period exceeding 90 minutes. After 3 hours of reaction, add 2,6-dimethylpyridine (423 mL, 3.73 mol) and DMAP (0.2 g, 0.0016 mol), followed by TFAA (157 g, 0.74 mol); the reaction mixture is allowed to reach room temperature within 2 hours. Dilute the mixture with EtOAc and water, then wash the organic phase successively with 3 NHCl, water, saturated NaHCO₃ solution, and saline solution. Dry the mixture with anhydrous Na₂SO₄ and filter through a silica gel stopper to obtain 165 g of crude product. Purify the crude product by rapid silica gel column chromatography using an eluent of ethyl acetate:hexane (1:5), yielding 120 g (75%) of 4,5-dehydroproline ethyl ester.

FAQ

A: pGlu stands for pyroglutamic acid (also known as 5-oxopyrrolidine-2-carboxylic acid) — a cyclic amino acid formed by intramolecular cyclization of glutamic acid. The pyroglutamate ring is a conformationally constrained scaffold commonly found in biologically active peptides.

Q2: What are the primary applications of Boc-pGlu-OEt?

A: Boc-pGlu-OEt is primarily used as a building block for introducing N-terminal pyroglutamic acid residues into peptides via Boc-strategy SPPS. It is also used as a chiral ligand in asymmetric synthesis.

Quality Assurance at Cosperpharm

 Gas chromatography (GC) – purity ≥97.0%

 Non‑aqueous titration – purity ≥97.0%

 Refractive index – confirmatory analysis

 ¹H NMR – structural verification

 Appearance – colorless to light yellow to light orange clear liquid

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

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