5-(4-Fluorophenyl)-2-(1-Methyl-Ethyl)-N,4-Diphenyl-1-[2-[(2R,4R)-Tetrahydro-Hydroxy-6-Oxo-2H-Pyran-2-Yl]Ethyl]-1H-Pyrrole-3-Carboxamide
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HS Code |
519678 |
| Chemical Name | 5-(4-Fluorophenyl)-2-(1-Methyl-Ethyl)-N,4-Diphenyl-1-[2-[(2R,4R)-Tetrahydro-Hydroxy-6-Oxo-2H-Pyran-2-Yl]Ethyl]-1H-Pyrrole-3-Carboxamide |
As an accredited 5-(4-Fluorophenyl)-2-(1-Methyl-Ethyl)-N,4-Diphenyl-1-[2-[(2R,4R)-Tetrahydro-Hydroxy-6-Oxo-2H-Pyran-2-Yl]Ethyl]-1H-Pyrrole-3-Carboxamide factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | 100 - gram pack of 5-(4 - Fluorophenyl)-2-(1 - Methyl - Ethyl)… chemical in sealed container. |
| Shipping | Shipment of 5-(4 - Fluorophenyl)-2-(1 - Methyl - Ethyl)-N,4 - Diphenyl - 1 - [2 - [(2R,4R)-Tetrahydro - Hydroxy - 6 - Oxo - 2H - Pyran - 2 - Yl]Ethyl]-1H - Pyrrole - 3 - Carboxamide is carefully packaged. It follows strict chemical shipping regulations, ensuring safe transit to its destination. |
| Storage | Store the chemical 5-(4 - Fluorophenyl)-2-(1 - Methyl - Ethyl)-N,4 - Diphenyl - 1 - [2 - [(2R,4R)-Tetrahydro - Hydroxy - 6 - Oxo - 2H - Pyran - 2 - Yl]Ethyl]-1H - Pyrrole - 3 - Carboxamide in a cool, dry place away from direct sunlight. Keep it in a tightly sealed container to prevent moisture absorption and protect from oxidizing agents. Avoid storage near heat sources or flammable materials. |
In the commercial synthesis of atorvastatin calcium, the (2R,4R)-lactone—chemically designated as 5-(4-fluorophenyl)-2-(1-methylethyl)-N,4-diphenyl-1-[2-[(2R,4R)-tetrahydro-4-hydroxy-6-oxo-2H-pyran-2-yl]ethyl]-1H-pyrrole-3-carboxamide—serves as the immediate penultimate intermediate prior to ring‑opening hydrolysis and calcium salt formation. The lactone-to‑acid conversion is conducted in aqueous sodium hydroxide at a concentration not exceeding 1.0 M to minimise epimerisation at the C‑3 and C‑5 chiral centres. The resultant (3R,5R)-dihydroxyheptanoic acid derivative is isolated via acidification to pH 4.0–4.5 with dilute hydrochloric acid, extracted into ethyl acetate, and then treated with a stoichiometric amount of calcium acetate monohydrate in a water‑ethanol mixture to precipitate atorvastatin calcium. Process yield from lactone to dried API typically falls within 85–92 % when temperature is maintained at 25 ± 2 °C and the hydrolysis residence time does not exceed 4 hours. In‑process control relies on chiral HPLC using a Chiralpak AD‑H column (250 mm × 4.6 mm, 5 µm) with a mobile phase of n‑hexane‑ethanol‑trifluoroacetic acid (85:15:0.1) at a flow rate of 1.0 mL/min and UV detection at 246 nm. The target enantiomeric excess after hydrolysis is >99.0 %; any excursion above 28 °C or pH 13 triggers an immediate batch hold for re‑analysis. The ring‑opening reaction is exothermic and is carried out in a 2000 L glass‑lined reactor equipped with a retreat‑curve impeller and jacket‑temperature control capable of removing 15 kW of heat. Nitrogen blanketing prevents oxidative discolouration of the pyrrole nucleus. Residual lactone in the final atorvastatin calcium API is controlled to ≤0.15 % by HPLC area, in line with the USP 43‑NF 38 monograph Individual Impurity Table, ensuring that the active pharmaceutical ingredient meets both ICH Q3A(R2) and regional pharmacopoeial acceptance criteria.
Pharmacopoeial Impurity E: System Suitability and Chromatographic QuantitationAtorvastatin lactone is listed as Impurity E in the European Pharmacopoeia (Ph. Eur. 10.0, monograph 2191) and as Atorvastatin Related Compound C in the United States Pharmacopeia (USP 43–NF 38). A certified reference standard of the lactone is prepared at a declared purity of ≥99.5 %, verified by mass balance (HPLC‑UV, Karl Fischer titration, and residual solvent analysis by headspace GC‑FID) and quantitative 1H‑NMR against an internal calibrant. Standard stock solutions are prepared in acetonitrile at 0.1 mg/mL and diluted to 1.0 µg/mL working strength using acetonitrile‑water (50:50 v/v). Storage of solid lactone standard is at −20 °C in a desiccator containing silica gel to prevent lactone hydrolysis from ambient moisture. System suitability test (SST) injections demand a resolution factor between atorvastatin lactone and atorvastatin acid of not less than 2.0 on an octadecylsilane column (150 mm × 4.6 mm, 3 µm) with mobile phase consisting of acetonitrile‑ammonium acetate buffer pH 4.0 (55:45 v/v), column temperature 35 °C, and detection at 246 nm. Retention time of the lactone relative to atorvastatin is typically 1.25–1.35; tailing factor must be ≤1.5. Quantitation uses the external standard method with correlation coefficient r² ≥0.999 over the range 0.5–5.0 µg/mL. Inter‑day precision at the specification limit level (0.15 % of the atorvastatin peak) yields a relative standard deviation below 5.0 %. This monograph-conformant HPLC procedure is employed both for release testing of atorvastatin calcium drug substance and for stability‑indicating assays on finished dosage forms.
When Does Atorvastatin Lactone Outperform the Acid Form in Caco‑2 Transport Assays?The lactone exhibits markedly higher passive permeability across Caco‑2 monolayers compared with the charged carboxylate species of atorvastatin, making it a pivotal tool in in vitro biopharmaceutics classification. In bidirectional transport studies on 21‑day differentiated Caco‑2 cells grown on polycarbonate inserts (0.4 µm pore, 1.12 cm² surface area), the apical‑to‑basolateral apparent permeability (Papp,A–B) of the lactone at 10 µM dosing in Hank’s balanced salt solution (pH 7.4) is routinely measured at 12–18 × 10⁻⁶ cm/s, while the acid form under identical conditions shows Papp,A‑B <3 × 10⁻⁶ cm/s. Efflux ratios (Papp,B–A/Papp,A–B) for the lactone remain 1.5–2.0, confirming modest P‑glycoprotein (P‑gp) interaction, whereas the acid displays ratios >5, consistent with strong active efflux via both P‑gp and breast cancer resistance protein (BCRP). These data, generated on the same donor cell line and quantified by LC‑MS/MS (lower limit of quantification 1.0 ng/mL), allow the lactone to be employed as a high‑permeability internal standard in Bio‑waiver justifications under ICH M9, where a compound’s BCS class boundary can be calibrated against the lactone’s intrinsic permeability. In hepatic uptake transporter studies using cryopreserved human hepatocytes, the lactone is metabolically hydrolysed to the acid within 15–30 min; kinetic assays must therefore include an esterase inhibitor cocktail (e.g., 1 mM phenylmethylsulfonyl fluoride and 0.1 % w/v bovine serum albumin) to stabilise the lactone during the 2‑minute initial uptake phase, otherwise hydrolysis artefacts falsely elevate the apparent acid accumulation.Stability‑indicating HPLC methods mandated under ICH Q1A(R2) require forced degradation studies in which atorvastatin calcium drug product is exposed to oxidative, photolytic, thermal, and pH‑stress conditions to assess lactone formation as a specific degradation product. In acidic hydrolysis experiments (0.1 N HCl, 60 °C, 24 h), titration of the calcium salt yields the open‑ring acid, which then cyclises to the lactone, with peak area percentages typically rising to 2.0–5.0 % of the parent drug peak. Under neutral pH stress (phosphate buffer pH 7.0, 60 °C, 48 h) lactone generation is limited to 0.3–0.7 %, whereas alkaline conditions (0.1 N NaOH, 25 °C, 6 h) cause complete ring opening and no detectable lactone accumulation. Thermal stress of solid dosage form at 80 °C for 14 days in sealed glass vials under nitrogen yields <0.2 % lactone, confirming that intramolecular esterification in the solid state is negligible if moisture content remains below 2.0 % w/w. Photodegradation per ICH Q1B Option 2 (overall illumination ≥1.2 million lux hours, UV energy ≥200 W·h/m²) increases lactone content by 0.5–1.5 %, and the degradation product is confirmed by co‑injection with the certified lactone reference standard as well as by LC‑QTOF‑MS (m/z 540.2 [M+H]⁺). Mass balance across all stress conditions remains between 95 % and 102 % when the lactone is integrated with the acid peak using a relative response factor of 1.1, fulfilling the USP <1225> validation requirements for stability‑indicating specificity.If the Lactone Ring Is Opened with Primary Amines, Amide‑Linked Statin Derivatives EmergeMedicinal chemistry groups exploit the lactone as a versatile chiral scaffold in the design of second‑generation HMG‑CoA reductase inhibitors. The δ‑valerolactone ring, when reacted with a primary amine (1.2 eq) in anhydrous tetrahydrofuran under argon at 0–5 °C for 12–18 h, undergoes nucleophilic acyl substitution to yield a (3R,5R)‑δ‑hydroxy‑amide derivative without racemisation, provided the amine pKₐ is below 10.5 and the reaction is quenched with ammonium chloride. The crude amide is isolated by silica gel flash chromatography (ethyl acetate‑hexane 3:1) and characterised by chiral SFC to confirm enantiomeric excess remains above 98.0 %. A panel of such amide analogues, where the amine component maps to heteroaryl‑methyl or cycloalkyl scaffolds, is screened in a recombinant human HMG‑CoA reductase catalytic domain assay (IC₅₀ measured at 37 °C with substrate HMG‑CoA at 20 µM and NADPH at 100 µM); the lactone‑derived amide series routinely yields IC₅₀ values from 8 nM to 350 nM. Compound solubility for these neutral amides is assessed via dynamic light scattering in fasted‑state simulated intestinal fluid (FaSSIF) before advancing to microsomal stability trials in human liver microsomes (protein concentration 0.5 mg/mL, NADPH‑regenerating system). The lactone itself serves as the starting material for each library due to its well‑documented crystallinity (melting point 158–160 °C) and single‑crystal X‑ray structure determination that defines the absolute configuration at C‑2 and C‑4, thereby obviating the need for chiral resolution late in the synthesis.In the context of biopharmaceutics permeability classification, the lactone form is routinely used as a high‑permeability reference marker in parallel artificial membrane permeability assays (PAMPA) conducted at pH 7.4 with a hexadecane‑based lipid barrier on a 96‑well filter plate. Effective permeability (Pₑ) values for atorvastatin lactone at 25 µM donor concentration average 9.2 × 10⁻⁶ cm/s, setting the borderline between high and low permeability classes per the FDA BCS guidance. This experimental cut‑off is applied to novel atorvastatin combination products where co‑formulated APIs are assessed against the lactone rather than metoprolol or antipyrine, because the lactone’s transport mechanism shares the same passive transcellular route and is not subject to paracellular leakage that plagues marker compounds with molecular weights below 300 Da. The method uses UV‑transparent plates read at 260 nm with a plate reader integration time of 0.2 s, and recovery mass balance across donor, membrane, and acceptor compartments exceeds 90 %. Acceptance criteria for the BCS biowaiver submission, as outlined in the EMA Guideline CPMP/EWP/QWP/1401/98 Rev 1, require the 90 % confidence interval of the geometric mean test/reference ratio for Pₑ to fall within 0.80–1.25 when the lactone is the calibrator, and the cross‑validation protocol is executed in at least three independent replicates on separate days.In‑line process analytical technology (PAT) in atorvastatin calcium manufacturing deploys the lactone both as a calibration standard and as a kinetic probe for real‑time conversion monitoring. An attenuated total reflectance Fourier‑transform infrared (ATR‑FTIR) probe, inserted into the glass‑lined hydrolysis vessel through a 25 mm Ingold port, records spectra every 15 seconds over the range 1800–1550 cm⁻¹. The lactone carbonyl stretch at 1728 cm⁻¹ decreases linearly with conversion, while the carboxylate asymmetric stretch of the ring‑opened acid at 1575 cm⁻¹ increases. A univariate calibration model constructed from 12 standard mixtures of lactone and atorvastatin sodium salt in the process solvent (water‑isopropanol 80:20) achieves a root mean square error of prediction below 0.8 % w/w at lactone fractions from 0.2 % to 100 %. The model is uploaded into the distributed control system; when the lactone peak area drops below the limit of quantification (0.1 %), the program triggers cooling and acidification steps. This closed‑loop approach reduces batch cycle time variability by 22 % compared with offline HPLC and prevents over‑hydrolysis events that would require reprocessing. The same lactone‑enriched standard mixtures are used for annual re‑qualification of the Raman immersion probe in the crystalliser, where the appearance of the lactone solid form (Form I) is discriminated from the amorphous atorvastatin calcium via characteristic bands at 1650 cm⁻¹ and 1004 cm⁻¹. |
Competitive 5-(4-Fluorophenyl)-2-(1-Methyl-Ethyl)-N,4-Diphenyl-1-[2-[(2R,4R)-Tetrahydro-Hydroxy-6-Oxo-2H-Pyran-2-Yl]Ethyl]-1H-Pyrrole-3-Carboxamide prices that fit your budget—flexible terms and customized quotes for every order.
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Cataloged as ATL-101 (Atorvastatin Lactone Reference Standard), the compound 5-(4-Fluorophenyl)-2-(1-Methyl-Ethyl)-N,4-Diphenyl-1-[2-[(2R,4R)-Tetrahydro-Hydroxy-6-Oxo-2H-Pyran-2-Yl]Ethyl]-1H-Pyrrole-3-Carboxamide is produced as a crystalline solid with a certified mass fraction purity of 99.2% ± 0.4% (expanded uncertainty, coverage factor k=2) determined by mass balance following the principles of ISO Guide 35. The substance is the δ-lactone form of the known HMG-CoA reductase inhibitor atorvastatin and serves as a primary impurity marker in pharmacopoeial monographs, including USP 43-NF 38 and Ph. Eur. 10.0. Its molecular formula is C₃₃H₃₃FN₂O₄, with a relative molecular mass of 540.63 g·mol−1. The solid exhibits a melting range of 158.7–160.2 °C (DSC, 10 K·min−1 under nitrogen, onset temperature) and a specific optical rotation of +38.2° (c=1.0, methanol, 20 °C, λ=589 nm), confirming the (2R,4R) configuration at the lactone ring. Residual solvent content is kept below 0.1% (wt/wt) for each Class 2 solvent by headspace GC-FID according to USP 〈467〉 Procedure A, while water content determined by Karl Fischer coulometric titration (USP 〈921〉 Method Ic) is consistently below 0.15%. The material is supplied in amber Type I glass vials under argon in quantities of 25 mg and 100 mg, with an assigned retest date of 24 months when stored at −20 °C ± 3 °C.
During batch certification, a combination of 1H NMR (600 MHz, CDCl₃), 13C NMR, and high-resolution mass spectrometry (ESI-TOF, resolution >30,000 FWHM) is employed. The 1H spectrum displays the characteristic ABX coupling of the lactone ring protons: δ 4.62 (ddd, J=8.3, 5.6, 2.9 Hz, 1H, H-4) and δ 2.73 (dd, J=17.8, 5.8 Hz, 1H, H-3a), δ 2.58 (ddd, J=17.8, 8.5, 2.5 Hz, 1H, H-3b). The pyrrole C-3 carboxamide carbonyl resonates at δ 165.9 in 13C, while the lactone carbonyl appears at δ 170.4. For chiral purity, a Chiralpak AD-H column (4.6 × 250 mm, 5 µm) with a mobile phase of n-hexane/ethanol/0.1% trifluoroacetic acid (85:15 v/v) at 1.0 mL·min−1 and UV detection at 244 nm achieves baseline separation of the (2R,4R) and (2S,4S) enantiomers; the undesired enantiomer is limited to an area-percent specification of ≤0.10%.
Typical lot release data are captured through the following table of validated analytical methods, all applied in a cGMP facility operating under 21 CFR 210/211. Any individual unspecified impurity is controlled at ≤0.10% area by the HPLC purity method (C18 column, 150 × 4.6 mm, 3.5 µm, gradient of acetonitrile and ammonium acetate buffer pH 4.0, detection at 240 nm).
| Test Parameter | Method & Equipment | Acceptance Criterion |
|---|---|---|
| Assay (mass fraction, as is) | Mass balance: HPLC purity × (1 − (water + R.S. + ROI)) per USP 〈35〉 | 98.0–102.0% |
| Water content | Karl Fischer coulometric, Metrohm 851 Titrando | ≤0.20% |
| Residual solvents | HS-GC-FID, Agilent 7890B with DB-624 column, 30 m × 0.32 mm, 1.8 µm film | Methanol ≤100 ppm; dichloromethane ≤60 ppm; toluene ≤80 ppm |
| Enantiomeric purity | Chiral HPLC, Chiralpak AD-H, UV 244 nm | Opposite enantiomer ≤0.10% |
| Elemental impurities | ICP-MS, USP 〈232〉/〈233〉 | Cd ≤0.5 µg/g, Pb ≤1.0 µg/g, As ≤1.5 µg/g, Hg ≤0.3 µg/g |
| Sulfated ash | Ph. Eur. 2.4.14 | ≤0.05% |
Thermogravimetric analysis (TGA) under nitrogen ramp (10 K·min−1 to 300 °C) shows no mass loss prior to decomposition, confirming the absence of significant surface moisture or trapped volatiles beyond the Karl Fischer value. The material is routinely shipped with a certificate of analysis that includes the exact lot-specific assay, chromatogram retention times, and a declaration of BSE/TSE compliance per EMA/410/01 Rev. 3.
One practical boundary encountered on the benchtop is the acid- and base-catalyzed interconversion between the lactone and the open-ring hydroxy acid form. In methanol–water mixtures buffered at pH 7.0 (ammonium acetate 50 mM), equilibrium reaches ~78% lactone within 4 hours at 25 °C; at pH 3.0 the lactone is stable for 24 hours, whereas at pH 9.0 complete hydrolysis occurs in under 15 minutes. Therefore, stock solutions for HPLC system suitability—typically a mixture of atorvastatin calcium and its lactone at a 10:1 ratio—must be prepared in acidified acetonitrile (0.01% v/v formic acid) and used within 8 hours at 4 °C to prevent artifact generation. The European Pharmacopoeia monograph for Atorvastatin Calcium Trihydrate (Ph. Eur. 2191) specifies a resolution factor of at least 2.0 between atorvastatin and the lactone impurity using a C18 column with a gradient of acetonitrile, tetrahydrofuran, and ammonium acetate buffer pH 4.0; typical system suitability injections on a Waters Acquity UPLC H-Class with a 1.7 µm column yield resolution values of 3.2–3.8.
In routine quality control laboratories, the three substances are differentiated by retention behavior, UV spectral purity, and fragmentation pattern. A second table condenses the chromatographic discrimination on a common USP method for Atorvastatin Tablets.
| Compound | RRT (HPLC, USP 43-NF 38 method) | Key MS2 Transition (m/z) | Dominant UV λmax (nm) |
|---|---|---|---|
| Atorvastatin calcium (acid form) | 1.00 | 559.3 → 440.2 | 245 |
| 5-(4-Fluorophenyl)-2-(1-Methyl-Ethyl)-N,4-Diphenyl- 1-[2-[(2R,4R)-Tetrahydro-Hydroxy-6-Oxo-2H-Pyran-2-Yl]Ethyl]-1H-Pyrrole-3-Carboxamide (Lactone) |
1.18 | 541.3 → 448.2 | 247 |
| Atorvastatin epoxide (3,5-diol, oxidized pyrrole) | 0.85 | 575.3 → 456.2 | 238 |
The lactone’s relative retention time of 1.18 is consistent across multiple C18 phases (Phenomenex Luna, Waters Symmetry, YMC-Pack Pro) at a column temperature of 30 °C ± 0.5 °C, while the epoxide elutes earlier due to the increased polarity of the diol function. Atorvastatin calcium, a dihydrate/trihydrate mixture, presents an additional operational difference: its hygroscopicity demands storage in tightly closed containers, whereas the lactone standard remains stable for months at −20 °C without desiccation. Furthermore, the lactone is not a direct intermediate in the final salt formation step of the API but arises predominantly as a degradation product under acidic stress; its limit in drug substance is harmonized at 0.15% area by ICH Q3A(R2). Published data on the conversion kinetics of atorvastatin acid to lactone under forced degradation (40 °C/75% RH, open dish, 7 days) indicate a formation rate of approximately 0.02% per day, meaning that the impurity is a sensitive marker of improper drying or packaging.
When the compound is employed as a reference marker in LC-MS/MS quantitation of atorvastatin in plasma, ion suppression from matrix components requires a deuterated internal standard such as atorvastatin-d5 calcium. The lactone, though structurally analogous, cannot serve as an internal standard due to the differential ionization efficiency (~30% reduction in positive mode ESI) and the variable lactone-hydroxy acid equilibrium in biological samples. This practical limitation is often noted in method development reports referencing bioanalytical method validation guidelines (EMA/CHMP/EWP/192217/2009 Rev. 2).
Groundwork in a cGMP-regulated environment includes a documented weighing procedure on a five-place analytical balance (Mettler Toledo XPR205) with a minimum sample mass of 10.0 mg to stay above the uncertainty threshold of the balance’s USP 〈41〉 repeatability requirement. A stock solution at 0.200 mg·mL−1 in acetonitrile is diluted to a working concentration of 2.0 µg·mL−1. The injection precision (RSD of peak area from six consecutive injections) must be below 1.0% for the standard to be acceptable. On a Shimadzu LC-20AD system with a photodiode array detector, the lactone peak asymmetry factor (Tailing factor per USP) is typically 1.05–1.12, indicating good column packing and no secondary interactions.
Acceptance criteria for a system suitability test include resolution between atorvastatin and lactone of ≥2.0, signal-to-noise ratio for the lactone peak at the reporting threshold of 0.05% of the API concentration exceeding 10:1, and a maximum allowed area% of the lactone in the standard blank below 0.03%. When the lactone is used to spike a placebo matrix for recovery studies in tablet assay, typical recovery at 0.15% spike level ranges between 92–105% (n=3) provided that the extraction solvent contains 0.005% (v/v) formic acid to suppress hydrolysis.
