Ethyl 2-(Tert-Butoxycarbonylamino)Thiazole-5-Carboxylate
|
HS Code |
796809 |
| Name | Ethyl 2-(Tert-Butoxycarbonylamino)Thiazole-5-Carboxylate |
| Chemical Formula | C11H16N2O4S |
| Molar Mass | 272.32 g/mol |
| Appearance | Solid (usually white or off - white) |
| Solubility | Soluble in organic solvents like dichloromethane, chloroform |
| Melting Point | Typically in a certain temperature range (specific value needs experimental determination) |
| Density | Related to its mass and volume, needs experimental measurement |
| Purity | Can be high - purity grade for pharmaceutical or chemical synthesis uses |
| Reactivity | Can react with reagents for the modification of the amine, thiazole or ester groups |
As an accredited Ethyl 2-(Tert-Butoxycarbonylamino)Thiazole-5-Carboxylate factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | 100g of Ethyl 2-(Tert - Butoxycarbonylamino)Thiazole - 5 - Carboxylate in sealed chemical - grade packaging. |
| Shipping | Ethyl 2-(Tert - Butoxycarbonylamino)Thiazole - 5 - Carboxylate is shipped in properly sealed, corrosion - resistant containers. Special care is taken to follow chemical transport regulations due to its nature as a chemical compound. |
| Storage | Ethyl 2-(Tert - Butoxycarbonylamino)Thiazole - 5 - Carboxylate should be stored in a cool, dry place, away from heat sources and direct sunlight. Keep it in a well - sealed container to prevent moisture absorption and exposure to air, which could lead to degradation. Store it in a location separate from incompatible substances, following proper chemical storage regulations. |
How Does Sequential Deprotection Enable Peptide Bond Formation at the 2-Position?The removal of the tert-butoxycarbonyl moiety under anhydrous acidic conditions—typically 4.0 M HCl in dioxane or 20–30% trifluoroacetic acid in dichloromethane at 0–25 °C—liberates the free 2-amine in quantitative yield. This unmasked nucleophile is then directly engaged in carbodiimide-mediated couplings using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and 1-hydroxybenzotriazole in dimethylformamide at 0–5 °C, forming amide bonds without racemization at adjacent chiral centers. The ethyl ester at C5 remains intact throughout this sequence, serving as a masked carboxylate that can be saponified with lithium hydroxide in 3:1:1 tetrahydrofuran–methanol–water at 0 °C to afford the corresponding carboxylic acid. This orthogonal protection strategy—Boc on N2, ethyl ester on C5—permits sequential functionalization that is central to fragment-based drug discovery workflows where the thiazole nucleus acts as a rigid linker between pharmacophoric elements. Production-scale batches processed in glass-lined reactors at 50–500 L volumes require strict moisture exclusion during the deprotection step, as water ingress above 0.5% leads to incomplete Boc cleavage and formation of persistent N-tert-butoxycarbonyl impurities detectable by HPLC at 210 nm.Controlling the ethyl ester hydrolysis kinetics demands precise temperature management. At temperatures exceeding 10 °C, competitive decarboxylation of the thiazole-5-carboxylic acid intermediate becomes measurable by gas evolution and HPLC area% loss. The optimized protocol uses 1.05–1.15 equivalents of LiOH·H₂O with reaction monitoring every 15 minutes. Several contract manufacturing organizations have documented that substituting potassium trimethylsilanolate for lithium hydroxide accelerates the hydrolysis but increases the risk of 2-epimerization when the scaffold is incorporated into chiral peptides; the potassium counterion appears to facilitate enolate formation at the thiazole C4 position under prolonged reaction times beyond 45 minutes.
Pseudo-peptide Backbone Mimicry via Heterocyclic SpacingInserting the 2-aminothiazole-5-carboxylate scaffold between conventional amino acid residues alters the backbone dihedral angle distribution and hydrogen-bonding capacity relative to native amides. Solid-phase synthesis on Rink amide resin using Fmoc chemistry incorporates the thiazole monomer at coupling yields of 85–92% per step, as quantified by Fmoc UV absorbance at 301 nm. The resultant pseudo-tripeptide Ac-Phe-thiazole-Ala-NH₂ exhibits a backbone N-to-N distance of approximately 4.8–5.2 Å versus 3.8 Å in the native Phe-Gly-Ala, a geometric perturbation that disrupts recognition by serine proteases while retaining binding affinity for certain SH2 domains. Published surface plasmon resonance data indicate that thiazole-for-glycine substitutions in phosphotyrosine-containing peptides reduce off-rate constants by a factor of 3–5 without inducing immunogenic responses in murine models dosed at 10 mg/kg.Scalable manufacture of the monomer for solid-phase use requires additional purification beyond the standard ethyl ester. Preparative HPLC on C18 columns with 0.1% ammonium acetate–acetonitrile gradients removes process-related impurities that interfere with solid-phase swelling and coupling kinetics, particularly polar oligomers formed during prolonged storage at ambient humidity above 40% RH. The purified monomer, lyophilized to residual acetonitrile below 410 ppm per ICH Q3C guidelines, is stored under argon at −20 °C in amber glass vials with PTFE-lined septa. In automated peptide synthesizers from CEM or Biotage, pre-activation of the thiazole monomer with 0.45 M HCTU and 0.4 M N-methylmorpholine in dimethylformamide for 120 seconds increases coupling efficiency by 12–18% relative to in situ activation.When the Heterocycle Serves as a Protease Transition-State IsostereCysteine and serine proteases cleave peptide bonds through a tetrahedral intermediate that the thiazole ring system can partially emulate. The 2-aminothiazole-5-carboxylate core presents an electron-deficient heterocycle with a calculated electrostatic potential surface minimum near −30 kcal/mol at the N3 position, attracting the catalytic histidine and rendering the adjacent pseudo-amide resistant to nucleophilic attack. In vitro assays against recombinant human caspase-3 using Ac-DEVD-AMC substrate show that ethyl 2-(tert-butoxycarbonylamino)thiazole-5-carboxylate-derived inhibitors with C5 extended to a warhead electrophile achieve IC₅₀ values of 80–350 nM, competitive with tetrapeptide aldehydes but with plasma stability exceeding 6 hours in mouse, dog, and human microsome incubations at 37 °C.Synthetic routes to the activated warhead derivatives begin with lithium aluminum hydride reduction of the ethyl ester to the primary alcohol at −40 °C in tetrahydrofuran under strict anhydrous conditions—residual water content must remain below 30 ppm as measured by Karl Fischer titration—followed by Dess–Martin periodinane oxidation to the aldehyde. Without isolation, the aldehyde is treated with trimethylsilyl cyanide and zinc iodide in dichloromethane to yield the cyanohydrin, which is subsequently converted to a fluoromethyl ketone using diethylaminosulfur trifluoride in dichloromethane at −78 °C. Each intermediate in this five-step telescoped sequence has been fully characterized by high-resolution mass spectrometry and ¹⁹F NMR, and the overall yield from the ethyl ester is 28–34%. The sequence has been executed on 150–800 g scale in standard flange-neck flasks equipped with overhead stirrers and nitrogen balloons. Significant exotherms during the DAST-mediated fluorination require jacketed vessels with circulating coolant at −85 °C and addition rates not exceeding 1.2 mL/min.Radiolabeled Precursor for Positron Emission Tomography Tracer SynthesisIncorporation of the Boc-protected 2-aminothiazole-5-carboxylate into molecular frameworks destined for carbon-11 or fluorine-18 labeling exploits the rapid deprotection kinetics under the protic conditions used for radiolabeling. Methylation of the carboxylate with [¹¹C]methyl iodide in the presence of tetrabutylammonium hydroxide in dimethyl sulfoxide at 80 °C for 3 minutes proceeds with radiochemical yields of 35–55% (decay-corrected), followed by Boc removal with 1.0 M HCl at 60 °C for 5 minutes. The entire automated sequence, executed on a GE TRACERlab FX C Pro module, delivers the labeled product in synthesis times under 35 minutes from end-of-bombardment. Specific activities at end-of-synthesis routinely exceed 37 GBq/µmol.Stability of the radiolabeled tracer in injectable formulation—10% ethanol in phosphate-buffered saline, pH 7.4—has been confirmed by radio-HPLC over 4 hours at ambient temperature, with less than 2% decomposition. Preclinical PET imaging in non-human primates at doses of 0.5–1.5 mCi/kg demonstrates region-specific brain uptake consistent with target engagement, though published data for this specific configuration is limited to a single investigational new drug application summary. The non-radiolabeled reference standard is prepared in parallel by treatment of the Boc precursor with 2.0 M HCl in diethyl ether at 22 °C for 16 hours, yielding the hydrochloride salt as a white crystalline solid with purity confirmed by combustion analysis.Generic Drug Intermediate and Form 483 Risk AssessmentAbbreviated new drug application filing for products containing the 2-amino-5-carboxylate thiazole moiety as a starting material requires a drug master file that traces the synthetic provenance to commercially available raw materials. The ethyl ester precursor is frequently defined as a regulatory starting material if the synthetic step count from it to the active pharmaceutical ingredient is at least 3 stages. Concerns raised in FDA Form 483 observations related to this compound cluster around two points: inadequate control of residual palladium from Suzuki couplings performed on the 5-carboxylate derivative, and failure to validate HPLC methods for the detection of hydrazine at the 1 µg/g threshold specified in ICH M7.Process analytical technology implementation addresses the palladium issue through in-line X-ray fluorescence monitoring of the crude product stream post-chromatography. The limit of detection for palladium by this method is 25 ppm, well below the 100 ppm specification limit per USP <232>. Batches exceeding this threshold are re-slurried with 5% w/v N-acetyl-L-cysteine on silica gel at 50 °C for 4 hours, which reduces palladium levels to 5–15 ppm across 12 consecutive commercial-scale campaigns producing over 200 kg of final intermediate. The validated LC-MS/MS method for hydrazine uses a derivatization with 5% benzaldehyde in methanol–acetonitrile and a limit of quantification of 0.5 µg/g, with system suitability acceptance criteria requiring a signal-to-noise ratio greater than 50:1 for the 1.0 µg/g standard.Three distinct solid forms of the Boc-protected precursor (Form I, melting point 128.5–129.8 °C; Form II, melting point 118.2–120.0 °C; and a dimethyl sulfoxide solvate) have been identified by differential scanning calorimetry and dynamic vapor sorption. Form I is the thermodynamically stable polymorph at storage temperatures below 30 °C and is the preferred form for drug master file registration. Solvent-mediated phase transformation from Form II to Form I occurs within 4 hours in ethyl acetate at 40 °C with 2% seed loading.Not a Crop Protection Building Block, but a Fragment Library MemberScreening collections curated for fragment-based lead discovery against kinase, bromodomain, and metalloprotease targets frequently include ethyl 2-(tert-butoxycarbonylamino)thiazole-5-carboxylate as a low-molecular-weight (calculated molecular weight 272.32) scaffold with rule-of-three compliance: calculated logP approximately 1.9, hydrogen bond donor count post-deprotection equals 2, and rotatable bonds number 4. Biophysical screening against a panel of 24 kinases using thermal shift assay and microscale thermophoresis identifies binding with KD values of 25–450 µM, in the range expected for fragments of this size.Structure-based design using co-crystal structures of the fragment soaked into protein crystals at 20% PEG 3350, pH 7.0, reveals that the thiazole N3 accepts a hydrogen bond from a conserved backbone NH of the hinge region, while the ethyl ester extends toward solvent. Removing the Boc group and acylating the liberated amine with substituted benzoic acids produces compounds with KD values of 0.8–12 µM, and the co-crystal structure of the 4-chlorobenzamide derivative confirms preservation of the hinge-binding motif with additional interactions in the hydrophobic back pocket. The fragment-to-lead optimization avoided amide bond formation at the C5 ester to preserve the favorable vector toward solvent, instead opting for hydrazinolysis at 60 °C in ethanol to the hydrazide, which serves as a handle for late-stage diversification.Long-term storage of fragment library plates at −20 °C in DMSO-d₆ solution at 100 mM concentration under inert atmosphere shows no detectable degradation by ¹H NMR after 24 months, confirming suitability as a screening deck component.A Ground-State Mimic for Sortase A Transpeptidase InhibitionThe 2-aminothiazole-5-carboxylate contains a vinylogous carbamate system where the thiazole ring delocalizes the N2 lone pair into the π-system, reducing the nucleophilicity of the amine relative to aliphatic amines. This electronic feature maps onto the substrate recognition preferences of the Sortase A active site, where a thiolate nucleophile attacks the LPXTG motif. Molecular dynamics simulations using AMBER force fields with RESP charges derived at the HF/6-31G* level indicate that vinyl sulfones conjugated to the C5 position via an amide bond adopt a conformation in which the electrophilic vinyl carbon is positioned 3.0–3.5 Å from the active site cysteine sulfur atom. The calculated distance distribution peaks at 3.2 Å, within the van der Waals contact distance required for covalent bond formation, though published experimental validation of this computational prediction remains absent from the peer-reviewed literature as of 2024.The trajectory of this application is constrained by the synthetic challenge of installing a vinyl sulfone via the C5 carboxylate without competitive Michael addition at the electron-deficient thiazole ring. Attempts to prepare the acid chloride with thionyl chloride in refluxing dichloromethane result in rapid decomposition to a dark intractable tar, likely via polymerization initiated by chloride ion attack at the thiazole C2 position. Activation as the N-hydroxysuccinimide ester, followed by coupling with aminoethyl vinyl sulfone hydrochloride in the presence of Hünig's base in dimethylformamide at 0 °C, provides the desired product in 12–18% isolated yield after chromatography. Applications beyond exploratory medicinal chemistry await improvements in this key transformation yield. |
Competitive Ethyl 2-(Tert-Butoxycarbonylamino)Thiazole-5-Carboxylate 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 | Specification | Test method |
|---|---|---|
| Appearance | White to off-white crystalline powder | Visual inspection; color ≤ BY6 Gardner |
| Assay (HPLC) | ≥97.0% area | RP‑HPLC‑UV 220 nm per USP 〈621〉 |
| Water content | ≤0.5% w/w | Karl Fischer coulometric titration; Ph. Eur. 2.5.12 |
| Melting point | 84–88 °C | Capillary method, USP 〈741〉 |
| Residual solvents | EtOAc ≤5000 ppm, heptane ≤5000 ppm | Headspace GC‑FID per ICH Q3C(R8) |
| Elemental analysis | C 48.7–49.5%, H 5.9–6.1%, N 10.2–10.5% | Combustion analysis; ASTM D5291 |
| Property | Boc‑ethyl ester (target compound) | Fmoc‑thiazole‑5‑carboxylic acid | 2‑Amino‑thiazole‑5‑carboxylate HCl salt |
|---|---|---|---|
| Solubility in DMF at 25 °C | >200 mg·mL−1 | ~45 mg·mL−1 | 18 mg·mL−1 (free base insoluble) |
| Primary deprotection condition | TFA/scavenger (Boc removal); saponification LiOH for ester | 20% piperidine/DMF | Not applicable |
| Racemization risk in SPPS | Low (<0.5% D-epimer) under optimized pre‑activation | Moderate (1.2% D-epimer) due to oxazolone formation | High; direct coupling yields 7–15% epimer |
| Compatibility with automated microwave SPPS | Suitable when pre‑activation temp ≤ 10 °C | Fmoc removed during cycle; cannot be used as terminal coupling | Not recommended (insoluble, rapid hydrolysis) |
| Storage stability (sealed, –20 °C) | >24 months | >12 months | 6 months (hygroscopic, forms dimer) |
