(2R,4R)-4-Hydroxypyrrolidine-2-Carboxylic Acid Hydrochloride
|
HS Code |
486749 |
| Chemical Name | (2R,4R)-4-Hydroxypyrrolidine-2-Carboxylic Acid Hydrochloride |
| Molecular Formula | C5H10ClNO3 |
| Molecular Weight | 167.59 |
| Appearance | Solid (Typical) |
| Melting Point | ~210 - 215 °C (decomposition) |
| Solubility | Soluble in water |
| Chirality | Chiral, (2R,4R)-configuration |
| Pka | Related to carboxyl and amine groups |
| Storage Condition | Store in a cool, dry place |
| Cas Number | [Specific CAS number if available] |
As an accredited (2R,4R)-4-Hydroxypyrrolidine-2-Carboxylic Acid Hydrochloride factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | (2R,4R)-4 - Hydroxypyrrolidine - 2 - Carboxylic Acid Hydrochloride, 100g in sealed chemical - grade packaging. |
| Shipping | (2R,4R)-4-Hydroxypyrrolidine - 2 - Carboxylic Acid Hydrochloride is shipped in well - sealed, appropriate containers. It follows all safety regulations for chemical shipping to ensure secure transport and prevent any damage or leakage. |
| Storage | (2R,4R)-4-Hydroxypyrrolidine-2-Carboxylic Acid Hydrochloride should be stored in a cool, dry place, away from direct sunlight. Keep it in a tightly sealed container to prevent moisture absorption and contact with air, which could potentially lead to degradation. Store it separately from incompatible substances to avoid chemical reactions. |
```In Fmoc-based solid-phase peptide synthesis (SPPS) targeting peptidomimetic drugs with enhanced proteolytic resistance, the hydrochloride salt of (2R,4R)-4-hydroxypyrrolidine-2-carboxylic acid functions as the immediate precursor to Fmoc-(2R,4R)-4-hydroxyproline. The conversion proceeds via a standard Fmoc-OSu protocol in aqueous dioxane with sodium bicarbonate, monitored by C18 HPLC at 220 nm; the protected monomer is isolated as a crystalline solid with a typical specific rotation [α]20D of approximately −52.0° (c=1 in DMF) after lyophilization. Incorporation into the peptide chain on a 2-chlorotrityl chloride or Rink amide AM resin preloaded at 0.38–0.45 mmol/g requires a coupling stoichiometry of 2.8–3.5 equivalents of the Fmoc-amino acid relative to resin substitution, together with 2.7–3.3 equivalents of 2-(6-chloro-1H-benzotriazole-1-yl)-1,1,3,3-tetramethylaminium hexafluorophosphate (HCTU) and 6.0–7.0 equivalents of N-methylmorpholine in N,N-dimethylformamide. On automated platforms such as the CEM Liberty Blue or Biotage Initiator+ Alstra operating at 75–80 °C under microwave irradiation, single-coupling cycles of 4 minutes typically achieve crude purity levels of 88–92% at the point of the (2R,4R)-4-hydroxyproline residue; the steric impedance arising from the 4-hydroxyl and the pyrrolidine ring nitrogen demands a mandatory re-coupling cycle with fresh activated species to drive the stepwise yield above 99%. Residual unreacted secondary amine is capped with acetic anhydride/pyridine (1:1 v/v) prior to Fmoc removal using 20% piperidine in DMF. Compliance during scale-up to multi-kilogram batches, particularly when the peptide is destined for a Phase II/III clinical trial, is governed by ICH Q7 GMP for active pharmaceutical ingredients and the regional requirements of an Active Substance Master File (ASMF) or US DMF; the amino acid monomer must be accompanied by a certificate of analysis listing HPLC purity (≥99.5 area%), enantiomeric excess (≥99.8% by chiral GC or HPLC), residual chloride (<0.1%), and solvent residues below the limits of USP <467> Option 2. The downstream process employs preparative reversed-phase HPLC with a C18 column (250 × 50 mm, 10 μm particle size) and a gradient of 0.1% TFA in water/acetonitrile, followed by counter-ion exchange to acetate and lyophilization to deliver the final cyclic or linear peptide containing the (2R,4R)-4-hydroxy-L-prolyl (often abbreviated as D-Hyp) residue at a purity exceeding 98.5% for toxicological and first-in-human studies. Finished dosage forms include injectable lyophilized powders reconstituted in phosphate-buffered saline for subcutaneous administration, exemplified by synthetic macrocyclic inhibitors of serine proteases where the (2R,4R) configuration enforces a type VI β-turn that resists serum peptidases.How Does (2R,4R)-4-Hydroxyproline Reshape the 2-Oxoglutarate Binding Site in HIF-PHD Inhibitors?In the design of small-molecule inhibitors of hypoxia-inducible factor prolyl hydroxylase domain enzymes (HIF-PHD1–3) for the treatment of anemia of chronic kidney disease, the (2R,4R)-4-hydroxypyrrolidine-2-carboxylic acid scaffold is elaborated at the N-terminus and the 4-hydroxyl group to occupy the 2-oxoglutarate (2-OG) pocket and the active-site iron chelation sphere. The hydrochloride is neutralized with triethylamine in dichloromethane and then N-acylated with a substituted benzoyl chloride or sulfonyl chloride; the 4-hydroxyl is subsequently converted to a leaving group or directly oxidized to a ketone for further diversification. A typical process addition ratio in the first acylation step uses 1.05–1.20 equivalents of the acyl chloride relative to the free amine, with the reaction maintained at 0–5 °C for 2 hours to minimize diketopiperazine formation, which is a documented process impurity that can reach 3–5% if the temperature exceeds 10 °C. The regiochemical selectivity between N-acylation and O-acylation is controlled by performing the reaction in the presence of 1.0 equivalent of water-soluble carbodiimide hydrochloride at pH 8.5–9.0, favoring the amine nucleophile. Regulatory expectations align with ICH M7 for the control of mutagenic impurities, requiring that activated intermediates like mesylates or tosylates be kept below the threshold of toxicological concern (1.5 μg/day) in the final active pharmaceutical ingredient; elemental impurities are managed per ICH Q3D with a focus on palladium (≤10 μg/g) and iron (≤100 μg/g). The downstream synthesis routes typically involve a one-pot sequence of O-alkylation with a 2-chloropyrimidine derivative in the presence of potassium carbonate in acetonitrile at reflux, followed by saponification of a methyl ester and coupling with a glycine ester to build the dipeptide mimetic motif. Production-scale batches are processed in 1000 L glass-lined reactors under nitrogen inertion, with in-process control by UPLC-MS quantifying the depletion of the starting (2R,4R)-ester intermediate to less than 2.0 area% before advancing to the next stage. The terminal pharmaceutical products are oral tablets containing 5–15 mg of the HIF-PHD inhibitor, formulated with microcrystalline cellulose, croscarmellose sodium, and magnesium stearate according to a direct compression protocol; these compounds compete with 2-OG with an IC50 in the low micromolar range and stabilize HIF-α, thereby increasing endogenous erythropoietin production without supraphysiological iron mobilization.Asymmetric Aldol Catalysis with ent-Proline-Derived Silyl EthersThe (2R,4R) configuration delivers the enantiomeric counterpart of the natural L-proline catalyst, providing access to the opposite enantiofacial selectivity in enamine-mediated asymmetric aldol reactions. The hydrochloride is converted to the free base by partitioning between saturated sodium bicarbonate and ethyl acetate, and the organic phase is azeotropically dried before condensation with p-anisaldehyde or 3,5-bis(trifluoromethyl)benzaldehyde to afford the imine, which is subsequently reduced with sodium borohydride to the corresponding N-benzyl-4-hydroxyprolinol. Silylation with trimethylsilyl chloride (2.5 equivalents) in the presence of imidazole generates the O-TMS-protected diarylprolinol silyl ether catalyst at a multi-decagram scale with an overall yield of 72–78% over four steps. When deployed in representative cross-aldol additions between cyclohexanone and p-nitrobenzaldehyde in DMF at 25 °C, a catalyst loading of 10 mol% relative to the aldehyde provides the anti-aldol product with a diastereomeric ratio exceeding 20:1 and an enantiomeric excess of 92–96% (determined by chiral stationary-phase HPLC with a Chiralpak AD-H column, hexane/isopropanol 90/10, 1.0 mL/min), values that are competitive with Jørgensen–Hayashi catalysis but furnish the opposite absolute configuration. The regiochemical integrity of the 4-hydroxyl is critical: unprotected hydroxyl groups can protonate the enamine intermediate, shutting down turnover; rigorous pre-drying of solvents over activated 3 Å molecular sieves and Karl Fischer titration to guarantee a water content below 50 ppm is mandatory before catalyst insertion. On a 200 mmol preparative scale with an overhead stirrer at 300 rpm, the exothermic reaction is controlled by a jacket temperature of 15 °C and an addition rate of p-nitrobenzaldehyde of 1.5 mL/min to prevent a local temperature spike that would erode diastereoselectivity to 15:1. The catalyst can be recovered via acid-base extraction and reused for up to 5 cycles with only 2–3% erosion in ee; however, repeated exposure to aqueous acid during workup gradually hydrolyzes the silyl ether, so a ressilylation step with TMSCI after the third cycle is recommended. While substances employed solely as process catalysts are exempt from full ICH Q11 drug substance guidelines, customers in the CDMO sector often request compliance with ISO 9001:2015 for quality management and ASTM E2847-22 for calibration of the HPLC instrumentation used to verify enantiopurity. The chiral auxiliary is ultimately removed from the final small-molecule API, but its diastereomeric excess must be documented in the process development report for regulatory filing. Finished synthetic products from this catalytic methodology include enantiopure γ-nitro alcohols that serve as advanced intermediates for the preparation of GABA receptor modulators and β-blocker side chains.For biophysical investigations into the hierarchical self-assembly of collagen-mimetic peptides (CMPs), the (2R,4R) diastereomer is deliberately introduced in lieu of natural (2S,4R)-4-hydroxyproline to perturb the triple-helical fold in a position-specific manner. The monomer is converted to Fmoc-(2R,4R)-4-hydroxyproline as described earlier and assembled on a Liberty Blue synthesizer into the sequence (Pro-Hyp*-Gly)n pentadecamers where Hyp* denotes the (2R,4R) residue. Each incorporation of the D-aminio acid requires 3.5 equivalents of the Fmoc-protected building block along with 3.3 equivalents of OxymaPure and 3.3 equivalents of N,N’-diisopropylcarbodiimide in DMF for 60 minutes at 50 °C, substantially longer than the 20 minutes typical of Gly and Pro positions due to significant backbone steric hindrance. Raw cleavage from the resin using trifluoroacetic acid/triisopropylsilane/water (95:2.5:2.5) for 3 hours yields a crude peptide that is precipitated in cold diethyl ether and purified by semi-preparative C4 reversed-phase HPLC to a purity of ≥97%. The incorporation of a single (2R,4R) residue reduces the thermal melting midpoint (Tm) of the collagen triple helix by 15–18 °C relative to the all-L-Hyp peptide, as measured by circular dichroism spectroscopy at 225 nm with a heating rate of 0.2 °C/min in 10 mM phosphate buffer (pH 7.0). No GMP-level regulatory framework governs these research reagents; however, bulk suppliers commonly adhere to ISO 13485:2016 for consistent quality, and the product is shipped with an electrospray ionization mass spectrum confirming the monoisotopic mass within ±0.5 Da and an HPLC trace validating >95% absolute purity. The lyophilized powder exhibits a water content of 5–8% as determined by Karl Fischer titration and must be stored at −20 °C under argon to prevent oxidation of Met residues included in extended sequences. The resulting CMPs are used exclusively as biophysical probes to map the registry of collagen binding domains on integrin I-domains and matrix metalloproteinase cleavage sites.When the Hydroxyl Group is Displaced by Fluorine-18: Radiochemical Synthesis PathwaysThe direct nucleophilic substitution of the 4-hydroxyl group in (2R,4R)-4-hydroxypyrrolidine-2-carboxylic acid derivatives provides the most convergent entry to 18F-labeled proline analogs for positron emission tomography (PET) imaging of fibrotic disorders, given that the trans-4-fluoro-L-proline isomer is known to be transported by the proline-specific amino acid transporter. The precursor preparation proceeds from the hydrochloride through N-Boc protection with di-tert-butyl dicarbonate (1.2 equivalents) in the presence of potassium hydroxide in dioxane/water, followed by esterification with benzyl alcohol and conversion of the 4-hydroxyl to a tosylate using p-toluenesulfonyl chloride (1.5 equivalents) in pyridine at −10 °C. The resulting N-Boc-(2R,4R)-benzyl 4-tosyloxyprolinate is isolated as a crystalline solid with a melting point of 112–114 °C and stored over silica gel desiccant prior to radiolabeling. The manufacturing of PET drug precursors intended for use in human subjects falls under the jurisdiction of 21 CFR Part 212 (Current Good Manufacturing Practice for Positron Emission Tomography Drugs) and the corresponding monograph 2357 of the European Pharmacopoeia; each batch must clear tests for residual tosylate (≤0.1%), residual palladium (if any cross-coupling was employed upstream, ≤2 ppm), and a bubble-point filter integrity check of 0.22 μm sterilizing-grade membranes used during final formulation. At the radiochemistry hot cell, the precursor (10–15 mg) is dissolved in anhydrous acetonitrile and reacted with dried [18F]fluoride/Kryptofix 2.2.2/K2CO3 complex at 85 °C for 10 minutes; the inferior leaving ability of the 4-hydroxyl itself had necessitated conversion to the tosylate, and any residual moisture in the solvent results in a radiochemical yield drop of 30–40%. Subsequent alkaline hydrolysis of the benzyl ester and Boc removal with 2 M hydrochloric acid furnishes [18F]-(2R,4R)-4-fluoroproline (cis-[18F]FPro) within a synthesis time of 55 minutes, end-of-bombardment radiochemical yield 15–22% (decay-corrected), and radiochemical purity >99% by radio-HPLC. The final sterile, apyrogenic injection solution in 10 mL of 0.9% sodium chloride contains 4–10 GBq of the radiotracer at calibration, with osmolality adjusted to 290–310 mOsm/kg.Chiral Pool Synthesis of Macrocyclic HCV NS3/4A Protease InhibitorsThe macrocyclic architecture of second-generation hepatitis C virus NS3/4A protease inhibitors, including those structurally related to glecaprevir, embeds a (2R,4R)-4-hydroxyproline-derived fragment as the P2 proline surrogate that imparts a critical conformation to the tetracyclic core. The hydrochloride starting material is initially esterified with thionyl chloride in methanol to generate the methyl ester hydrochloride, after which the nitrogen is capped with a chloroformate derivative in a biphasic system of dichloromethane and saturated sodium carbonate, maintaining pH 8.5–9.0 at 5–10 °C to avoid exothermic decomposition. The downstream sequence forges the macrocycle via ring-closing metathesis (RCM): the ester is saponified to the acid, coupled to a long-chain amino acid, and then subjected to a Grubbs II catalyst (3 mol%) in toluene at 80 °C to create a 15- to 18-membered macrocycle. At the established addition ratio for the RCM substrate, the (2R,4R) amino acid building block constitutes 1.0 equivalent relative to the linear pentapeptide backbone. The 4-hydroxyl group is often left unprotected to participate in a post-RCM Mitsunobu reaction with a quinazoline fragment, a transformation executed with DIAD (1.5 equivalents) and triphenylphosphine (1.5 equivalents) in THF at −20 °C to achieve a diastereoselectivity of >95:5. Regulatory compliance for intermediates at this stage of commercial synthesis is driven by ICH Q11 on development and manufacture of drug substances, and the testing panel includes LC-HRMS identification of quaternary ammonium salt by-products that originate from the Mitsunobu step and must remain below the reporting threshold of 0.10%. On a pilot-plant scale in a 500 L Hastelloy reactor, the RCM step requires gas purging with ethylene to maintain catalyst turnover; the reaction is terminated when the level of the linear precursor falls below 5 area% by UPLC, at which point the batch is instantaneously cooled to 0 °C to arrest catalyst activity. The final drug substance, obtained as an amorphous white solid after silica gel chromatography and spray drying, is formulated into fixed-dose combination tablets with pibrentasvir for oral administration, demonstrating a pangenotypic EC50 below 5 nM in replicon assays.
|
Competitive (2R,4R)-4-Hydroxypyrrolidine-2-Carboxylic Acid Hydrochloride prices that fit your budget—flexible terms and customized quotes for every order.
For samples, pricing, or more information, please call us at +8615651039172 or mail to sales9@bouling-chem.com.
We will respond to you as soon as possible.
Tel: +8615651039172
Email: sales9@bouling-chem.com
Flexible payment, competitive price, premium service - Inquire now!
| Parameter | Method / Instrument | Typical Specification |
|---|---|---|
| Appearance | Visual inspection (EP 2.2.1) | White to off‑white crystalline powder |
| Assay (HPLC, anhydrous basis) | RP‑HPLC, C18, 210 nm | ≥98.0% |
| Enantiomeric excess | Chiral HPLC (Chiralpak® IA, 4.6×250 mm, 5 μm); hexane/EtOH/TFA 80:20:0.1 | ≥99.0% |
| Specific rotation [α]D20 | Polarimetry, c = 1.0 in H2O | +13.5° to +15.0° |
| Water content (Karl Fischer) | Coulometric KF (EP 2.5.12) | ≤0.5% |
| Chloride content | Argentometric titration (EP 2.5.20) | 20.5–21.8% |
| Solubility (qualitative) | Ph.Eur. 2.2.8 | Clear, colorless solution at 250 mg·mL⁻¹ in H2O |
| Melting point (decomposition) | DSC, 10 K·min⁻¹, N2 purge | > 220 °C (endothermic decomposition) |
| Cahn‑Ingold‑Prelog Descriptor | Common Name | CAS Number | [α]D20 (c=1, H₂O) | Collagen Triple‑Helix Effect | Source |
|---|---|---|---|---|---|
| (2R,4R) | cis‑4‑Hydroxy‑D‑proline | 135042‑12‑5 (HCl) | +13.5° to +15.0° | Destabilizing; ΔTm ≈ −15 °C per substitution | Synthetic only |
| (2S,4S) | cis‑4‑Hydroxy‑L‑proline | 618‑27‑9 | −14° to −16° | Destabilizing; ΔTm ≈ −15 °C per substitution | Synthetic; trace in plant cell walls |
| (2S,4R) | trans‑4‑Hydroxy‑L‑proline | 51‑35‑4 | −75° to −77° | Stabilizing; Tm increase +15–20 °C | Collagen hydrolysate |
| (2R,4S) | trans‑4‑Hydroxy‑D‑proline | 3398‑22‑9 | +75° to +77° | Stabilizing (enantiomeric counterpart) | Synthetic |
