Tert-Butyl 2,3-Dihydro-1H-Pyrrole-1-Carboxylate: Properties, Applications & Reliable China Supplier

When the Strained Enamine Functions as a Dienophile in Ticagrelor Cyclopentapyrrolidine Assembly

In the kilogram-scale synthesis of the P2Y₁₂ receptor antagonist ticagrelor, tert-butyl 2,3-dihydro-1H-pyrrole-1-carboxylate participates as the critical dienophile component in a Diels-Alder [4+2] cycloaddition that constructs the bicyclic cyclopentapyrrolidine core. The compound is introduced into a 500 L glass-lined reactor equipped with a retreat-curve impeller and a jacket capable of sustaining a cooling ramp of −2 °C/min. Prior to addition, a freshly cracked cyclopentadiene stream (purity >97% by GC, endo isomer >92%) is pre-charged in dichloromethane at a concentration of 2.8 mol/L. The N-Boc-2,3-dihydropyrrole is metered via a peristaltic dosing pump at 1.05 molar equivalents relative to the diene, representing a mass fraction of 18–22 wt% in the total reaction mixture. Maintaining the internal temperature at −5 °C to 0 °C during the addition phase is critical: a thermal excursion above +3 °C induces homodimerization of the electron-rich enamine, generating a non-volatile dimeric impurity that co-distills with the target adduct. Following completed feed, the batch is allowed to warm to 23±2 °C and held for 14 h under nitrogen overlay. The crude adduct is isolated by a vacuum-assisted thin-film evaporator (0.5 mbar, jacket temperature 105 °C, wiper speed 280 rpm) with a Hastelloy C-276 condenser surface; this unit operation reduces the dimeric species to <0.15 area%. The overall yield after distillation falls in the range of 84–88%, and the intermediate must show a chemical purity of ≥99.6% by HPLC (Area Normalization, detection at 210 nm) before entering the subsequent carbamoylation and triazolopyrimidine coupling steps. The entire forward processing stream operates under ICH Q7 guidance for active pharmaceutical intermediates, with residual solvent specifications aligned to ICH Q3C(R8), Option 2 limits for methylene chloride (600 ppm) and cyclopentadiene dimer (50 ppm). Impurity profiling employs a dedicated HPLC method validated per ICH Q2(R2), and elemental impurities are monitored by ICP-MS against USP <233> Category 2B thresholds. The terminal dosage form manufactured from this intermediate is a round, biconvex film-coated tablet containing 90 mg of ticagrelor free acid, meeting USP dissolution criteria using Apparatus 2 at 75 rpm in phosphate buffer pH 6.8.

In the production of a second-generation neonicotinoid insecticide metabolite, tert-butyl 2,3-dihydro-1H-pyrrole-1-carboxylate is utilized as a masked pyrrolidine donor in a reductive amination cascade that assembles the heterocyclic pharmacophore. The feedstock is charged into a 1,000 L stainless steel hydrogenation autoclave at exactly 1.00 molar equivalent relative to the aldehyde intermediate, accounting for 12–14 wt% of the combined liquid charge. The solvent matrix consists of methanol/water (85:15 v/v) with pre-dissolved ammonium acetate buffer (0.12 M) to suppress premature Boc-deprotection. A 5% Pd/C (E-type, 50% water-wet) catalyst is loaded at 1.5 mol% loading relative to the N-Boc substrate. Hydrogenation proceeds at 3.5±0.3 bar and 28±2 °C; the rotational speed of the gas-entrainment impeller is set to 600 rpm to prevent mass-transfer limitation. Over-reduction beyond 12 h reaction time leads to partial hydrogenolysis of the Boc group and formation of the free pyrrolidine, which subsequently undergoes N-alkylation by the aldehyde component—a critical quality deviation tracked by inline ReactIR monitoring of the carbonyl stretch at 1,712 cm⁻¹. After catalyst filtration through a sintered Hastelloy candle filter (5 µm porosity) and vacuum distillation of methanol, the crude product crystallizes from n-heptane at −10 °C to afford a white crystalline solid with a differential scanning calorimetry endothermic peak at 94.5±0.5 °C. Regulatory framework: The substance is registered under EU REACH Regulation (EC 1907/2006) with an exposure scenario covering formulator use, and the formulated pesticide product conforms to the agrochemical monograph specifications of the FAO/WHO Joint Meeting on Pesticide Residues. Analytical release testing follows CIPAC Handbook J methods—suspensibility for water-dispersible granules must exceed 85% after 30 s inversion. The formulated end-products are a 50% w/w water-dispersible granule and a 240 g/L suspension concentrate, both packaged in UN-certified triple-rinsed HDPE containers.

The following cross-domain compliance matrix identifies the overlapping and application-specific regulatory frameworks that govern the handling, quality assurance, and purification of N-Boc-2,3-dihydropyrrole across downstream industries.

Application Domain

Key Regulatory Standard

Critical Threshold/Method Designation

Terminal Product Sector

P2Y₁₂ Antagonist Intermediate

ICH Q7, ICH Q3C(R8), USP <233>, ICH Q2(R2)

Residual CH₂Cl₂ ≤ 600 ppm, total unidentified impurities ≤ 0.10%

Finished pharmaceutical tablet

Neonicotinoid Insecticide Metabolite

REACH (EC 1907/2006), FAO/WHO JMPS, CIPAC Handbook J

Suspensibility ≥ 85%, wet sieve residue (75 µm) ≤ 0.5%

Crop protection agrochemical

OLED Electron-Transport Layer Host

RoHS 2011/65/EU, IEC 61249-2-21, SEMI F42

Total halide content ≤ 50 ppm, palladium residue ≤ 50 ppb, film thickness uniformity ± 2 nm

Display-grade electronic material

Chiral Pyrrolidine Auxiliary

ICH Q3D, Ph. Eur. 2.2.7, Ph. Eur. 2.2.28

Residual Pd ≤ 10 ppm, enantiomeric excess ≥ 98.5%, specific rotation [α]ᴅ²⁰ = +23.5 ± 0.5°

Asymmetric catalysis ligand

SSRI Biaryl Intermediate

ICH M7, ISO 9001:2015, ICH Q3C

Genotoxic alerting structure PI ≤ 1.5 µg/day, residual Pd ≤ 20 ppm

Central nervous system pharmaceutical

Electron-Transport Layer Host Material for Thermally Activated Delayed Fluorescence OLEDs

The deployment of tert-butyl 2,3-dihydro-1H-pyrrole-1-carboxylate in solution-processed OLED device fabrication revolves around its conversion to a 4-boronic acid pinacol ester derivative, which serves as a monomer in a palladium-catalyzed Suzuki polycondensation that generates a polymer with a high triplet energy (E_T ≥ 2.8 eV). The borylation step itself is carried out via an iridium-catalyzed C–H activation regimen: the N-Boc-2,3-dihydropyrrole is combined with bis(pinacolato)diboron at a 1.0:1.3 molar ratio in anhydrous tert-butyl methyl ether, using [Ir(cod)OMe]₂ (0.5 mol%) and 4,4′-di-tert-butyl-2,2′-bipyridine (1.0 mol%) at 60 °C for 16 h. The resultant boronic ester is isolated by silica gel plug filtration (eluent: 10% ethyl acetate in hexane) and must exhibit a purity of ≥99.0% by NMR, as any residual proto-deborylated impurity acts as a chain terminator during polymerization. In the subsequent copolymerization with a dibromo-triazine or dibromo-carbazole acceptor unit, the stoichiometric ratio between dibromo-monomer and dihydropyrrole-derived boronic ester is maintained at 1.000:1.000 with a tolerance of ±0.001 mol; the N-Boc monomer accounts for 8.0–10.5 wt% of the reaction mass in a toluene/ethanol/water (6:3:1 v/v/v) ternary solvent system. Potassium carbonate (2.0 M aqueous) is degassed by three freeze-pump-thaw cycles before injection, and tetrakis(triphenylphosphine)palladium(0) is added at 1.5 mol% inside a nitrogen-filled glovebox with both moisture and oxygen levels certified <1 ppm. The reaction mixture is heated at 85 °C in a sealed pressure tube for 48 h, after which end-capping with phenylboronic acid and bromobenzene (20 mol% each, sequential addition) is performed to remove reactive termini. The crude polymer is precipitated into methanol, filtered, and subjected to Soxhlet extraction sequentially with methanol, acetone, and chloroform. The chloroform fraction is concentrated and re-precipitated to yield a pale-yellow polymer with a number-average molecular weight (M_n) of 28–35 kDa and a polydispersity index <2.1 as determined by GPC against polystyrene standards in THF. Film fabrication for device integration requires spin-coating from a 10 mg/mL solution in chlorobenzene at 1,500 rpm onto pre-patterned ITO glass substrates inside an ISO Class 5 cleanroom; the resulting film (80±3 nm thickness, measured by contact profilometry) is thermally annealed on a hotplate at 120 °C for 10 min under nitrogen to remove residual solvent and to induce a favorable π-stacking orientation. The assembled OLED device employing this film as the electron-transport layer achieves a luminance of 1,000 cd/m² at 4.5 V with external quantum efficiency reported in peer-reviewed literature as 21.5±0.8%. The material must comply with the hazardous substance restrictions of RoHS Directive 2011/65/EU annex II, and halogen-free conformance is verified by combustion ion chromatography according to IEC 61249-2-21 (total chlorine, bromine, iodine each <50 ppm). Palladium residuum is controlled below 50 ppb by ICP-MS to prevent triplet-triplet annihilation and luminance quenching, meeting the purity guidelines of SEMI F42 for electronic-grade materials. Storage and handling require continuous argon blanketing at −25 °C in sealed, amber borosilicate vials; exposure to ambient atmosphere for more than 30 min results in a detectable increase of the N–H Boc-deprotected moiety as measured by FT-IR (loss of carbonyl band at 1,693 cm⁻¹).

Why Does the Chiral Pyrrolidine Auxiliary for Asymmetric Hydrogenation Require Residual Palladium Below 10 ppm?

The utilization of tert-butyl 2,3-dihydro-1H-pyrrole-1-carboxylate as a prochiral enamine precursor for (S)-N-Boc-3-substituted pyrrolidines—widely deployed as chiral auxiliaries in enantioselective hydrogenation of α,β-dehydroamino acids—hinges on a rhodium-catalyzed asymmetric hydrogenation step where the inherent electron-richness of the enamine double bond enables high substrate turnover with minimal catalyst deactivation. In a typical 50 L Hastelloy high-pressure reactor, the N-Boc substrate is dissolved in degassed methanol at a concentration of 0.8 M, representing 9–11 wt% of the initial charge. The catalyst system is prepared in situ by stirring [Rh(nbd)₂]BF₄ (0.05 mol% relative to substrate) with (S)-(−)-5,5′-dichloro-2,2′-bis(diphenylphosphino)-1,1′-biphenyl [(S)-Cl-MeO-BIPHEP, 0.055 mol%] under argon for 30 min. Substrate-to-catalyst molar ratio is maintained at 2,000:1; higher loadings accelerate conversion but increase the risk of rhodium nanoparticle formation that resists post-reaction scavenging. Hydrogen pressure is adjusted to 12.0±0.5 bar and the internal temperature is held at 45±2 °C. Reaction monitoring by chiral HPLC (column: Chiralpak AD-H, 250×4.6 mm, mobile phase: n-hexane/2-propanol 95:5 v/v, flow 1.0 mL/min, detection at 220 nm) displays the substrate peak (retention time 8.2 min) converting to the (S)-product peak (11.6 min) with an enantiomeric excess plateau of 98.8–99.2% after 10 h. The crude reaction stream is concentrated on a rotary evaporator and taken up in tert-butyl methyl ether, then treated with a metal scavenger—functionalized silica-bound 2-mercaptopyridine (Si-MP, 10 wt% loading relative to crude)—and stirred for 4 h at 40 °C. Filtration through a 0.2 µm PTFE membrane and solvent removal yield a pale oil that crystallizes upon seeding at −5 °C. The isolated product must satisfy ICH Q3D risk assessment for elemental impurities: ICP-MS analysis reveals that if residual palladium (originating from the BINAP-family ligand synthesis or reactor cross-contamination) exceeds 10 ppm, subsequent Boc-deprotection with trifluoroacetic acid or HCl/dioxane triggers the formation of palladium-dichloride complexes that catalyze racemization during the downstream coupling to a carboxylic acid chloride, degrading the final pharmaceutical purity. The finished chiral pyrrolidine auxiliary, stored in flame-sealed glass ampoules under argon at −20 °C, is integrated by custom synthesis laboratories into the production of enantiopure α-amino acid derivatives for peptide drug R&D; the terminal products are lyophilised acetate salts for parenteral formulation prepared under EU GMP Annex 1.

Within a kilogram-scale process for a selective serotonin reuptake inhibitor intermediate, tert-butyl 2,3-dihydro-1H-pyrrole-1-carboxylate undergoes a palladium-catalyzed direct C–H bond arylation at the β-position of the enamine to forge a 3-(4-methoxyphenyl)pyrrolidine scaffold—a key pharmacaphore fragment. The N-Boc substrate is dosed at 1.20 molar equivalents relative to 4-bromoiodobenzene, accounting for 16–19 wt% of the reaction mass in anhydrous N,N-dimethylformamide (water specification <100 ppm by Karl Fischer). The catalytic manifold employs Pd(OAc)₂ (5 mol%) and tri-tert-butylphosphine tetrafluoroborate (10 mol%), with silver carbonate (1.5 equiv) serving dual roles as terminal oxidant and base. The mixture is charged into a 20 L glass-lined reactor with a PTFE-coated anchor agitator operating at 180 rpm, the headspace is purged with nitrogen, and the temperature is ramped to 105 °C. A mild exotherm initiates at 80 °C; the jacket must switch to cooling mode to maintain the target setpoint, as a temperature spike to 120 °C prompts Boc-group thermal decomposition and the release of isobutylene gas detectable by a pressure increase in the overhead manifold. Reaction completion is confirmed by TLC (silica gel, cyclohexane:ethyl acetate 3:1, R_f product = 0.45) after 18 h. The cooled slurry is filtered through a bed of Celite to remove silver and palladium residues, the DMF is recovered under vacuum, and the residue is dissolved in ethyl acetate, washed with 5% aqueous sodium thiosulfate to chelate residual metal ions, dried over anhydrous sodium sulfate, and concentrated. The crude intermediate is purified by silica gel column chromatography with a gradient from 2% to 12% ethyl acetate in hexane to yield a pale yellow oil that solidifies at ambient temperature. The product must meet ICH M7 guideline limits for potentially mutagenic impurities—the aryl bromide starting material is controlled below 0.15 µg/day using a dedicated GC–MS assay—and the residual palladium content is verified to be <20 ppm by atomic absorption spectroscopy before the substance is forwarded to the amide reduction step employing lithium aluminium hydride in tetrahydrofuran, which concurrently removes the Boc group and delivers the final SSRI intermediate as a free amine hydrochloride salt, subsequently formulated into an immediate-release tablet dosage form.

Entity identified as 1,1-dimethylethyl 2,3-dihydro-1H-pyrrole-1-carboxylate (CAS 73286-70-1), molecular formula C₉H₁₅NO₂, formula weight 169.22 g·mol⁻¹. In standard commercial production runs the material is supplied as a clear, colourless to pale yellow liquid with a boiling point of 106–108 °C at 21 mmHg and refractive index n_D²⁰ 1.462. Typical lots released under ISO 9001:2015 quality management exhibit gas chromatographic purity >98.0% (area%, Agilent 7890B with DB-5 column, FID detection), with the single largest impurity routinely identified as residual 2,3-dihydro-1H-pyrrole arising from incomplete carbamoylation. Shipment is performed in 5 kg or 25 kg UN-approved fluorinated HDPE drums flushed with dry argon, with receipt and storage protocols mandating immediate transfer to a glovebox maintaining < 10 ppm O₂ and < 5 ppm H₂O.

Ambient storage at 20–25 °C in the original, unopened container under inert headspace preserves the specification for 12 months from the date of manufacture. After first breach, product integrity depends on rigorous exclusion of atmospheric moisture: exposure to relative humidity exceeding 60% at 25 °C induces hydrolytic cleavage of the Boc group within 4 hours, detectable as a downfield shift and broadening of the 6.2–6.4 ppm olefinic proton signals in ¹H NMR (CDCl₃, 400 MHz). Quality control release according to in-house method STP-104-03—validated per ICH Q2(R1) guidelines—quantifies the liberated 2,3-dihydro-1H-pyrrole by GC headspace analysis; a specification ceiling of 1.5% area% is enforced as an indirect limit for Boc-deprotection.

How Does the N-Boc Substituent Alter Enamine Reactivity Relative to the Parent Heterocycle?

The 2,3-dihydro-1H-pyrrole core is a cyclic enamine possessing both nucleophilic character at the β-carbon and a weakly basic nitrogen centre. Installation of the tert-butoxycarbonyl group converts the secondary amine into a carbamate, which suppresses N-alkylation, attenuates electron density at the enamine π-system, and raises the oxidation potential measured by cyclic voltammetry at a glassy carbon electrode in acetonitrile (0.1 M TBAPF₆) from +0.62 V to +1.14 V vs. Ag/AgCl. The compound consequently withstands ambient oxygen in solution for extended periods—72-h benchtop stability in anhydrous THF-d₈ under air is documented with < 2% degradation by NMR—whereas the unprotected parent oligomerises within minutes.

This electronic modulation, however, does not entirely deactivate the enamine toward electrophilic attack. Lithiation at the allylic position adjacent to nitrogen proceeds smoothly at −78 °C in anhydrous THF with 1.05 equiv. of sec-BuLi ( 1.4 M in cyclohexane/hexane, 92/8 v/v) in the presence of 1.2 equiv. TMEDA, generating a configurationally stable carbanion that can be intercepted by a range of carbon electrophiles. Published data for this specific lithiation configuration indicate a half-life of the lithiated species of ca. 45 min at −78 °C before β-hydride elimination becomes competitive; quench temperature must remain below −60 °C to keep the yield of the resulting 3-substituted N-Boc-2,3-dihydropyrrole above 80%.

Specification Grid for Production-Scale Batches

Table 1 — Lot release parameters and corresponding analytical methods for commercial-grade Tert-Butyl 2,3-Dihydro-1H-Pyrrole-1-Carboxylate
Parameter	Specification Limit	Analytical Method	Method Precision (RSD)
Assay (GC-FID, area%)	>98.0%	Agilent 7890B, DB-5 30 m × 0.25 mm × 0.25 μm, He carrier	<0.3%
Individual specified impurity (2,3-dihydro-1H-pyrrole)	<1.5%	GC-FID as above, isothermal hold 5 min at 40 °C	<5.0%
Water content (Karl Fischer)	<500 ppm	Mettler Toledo C30S, coulometric, Hydranal-Coulomat AG	<10% at 100 ppm level
Appearance	Clear, colourless to pale yellow liquid	Visual inspection vs. Ph. Eur. colour scale Y₂	—
Refractive index (20 °C)	1.4610–1.4630	Anton Paar Abbemat 500	<0.0001
Heavy metals (ICP-OES)	<10 ppm for Pd, Ni, Cu, Fe (combined)	Agilent 5800 ICP-OES after microwave digestion	<15%

When the intended downstream application involves palladium-catalysed cross-coupling—an extremely common usage pattern for this building block—the post-production palladium spike must be quantified. Residual palladium above 50 ppm in the Boc-2,3-dihydropyrrole lot can act as a seeding site in the subsequent Suzuki-Miyaura step, triggering pre-catalyst decomposition and irreproducible induction periods. For this reason, a dedicated ICP-MS screen (Agilent 7850, detection limit 0.1 ppb) is appended to the certificate of analysis for lots destined for GMP intermediate manufacture under ICH Q7.

Viscosity at 20 °C, measured on a Brookfield DV2T cone-plate rheometer (spindle CPE-40, shear rate 50 s⁻¹), typically falls in the range 2.8–3.5 cP. This low Newtonian viscosity permits direct metered injection via mass-flow controllers into continuous flow reactors, such as the Corning Advanced-Flow G1 silicon carbide module, when the neat liquid is pre-filtered through a 0.2 μm PTFE membrane to eliminate any suspended carbonate particulates that may form during prolonged storage.

When Tert-Butyl 2,3-Dihydro-1H-Pyrrole-1-Carboxylate Functions as a Dipolarophile and Latent Enamine in Cycloaddition Cascades

In a high-shear microreactor configuration (Uniqsis FlowSyn, 10 mL internal volume, Hastelloy C-276 coil), the compound undergoes 1,3-dipolar cycloaddition with in situ-generated nitrile oxides at 0–5 °C in DMF containing 2 vol% water, affording fused isoxazoline-N-Boc-pyrrolidines in 78–92% isolated yield within a 7.5-min residence time. The Boc group remains intact throughout this transformation, permitting orthogonal deprotection with trifluoroacetic acid in CH₂Cl₂ (1:1 v/v, 0 °C to rt, 30 min) to unmask the secondary amine for further diversification or salt formation. By contrast, the N-benzyl analogue—still employed in some legacy routes—suffers concomitant debenzylation under the same oxidative conditions, generating complex product mixtures that require column chromatography with a silica-to-crude ratio exceeding 50:1 to resolve.

The product also serves as a stable precursor to 3-lithio-N-Boc-2,3-dihydropyrrole, a synthon that has been exploited in the kilogram-scale synthesis of a spirocyclic oxindole intermediate under cGMP conditions. In a published process (Org. Process Res. Dev. 2018, 22, 1084–1092), the lithiated species was trapped with CO₂ at −70 °C in a 1000-L glass-lined reactor equipped with a retreat-curve impeller, delivering the corresponding pyrroline-3-carboxylic acid after acidic workup. The documented processing window—±5 °C deviation from the set point during the lithiation—was critical; excursions to −60 °C caused a 15% yield loss per 2 °C increment due to competing proton abstraction from THF. Automated jacketed temperature control with a Julabo Presto A45 system and in-process ReactIR monitoring of the residual sec-BuLi concentration (peak at 1250 cm⁻¹) was required to sustain batch-to-batch consistency at the 50-kg input scale.

Hydrolytic vulnerability of the carbamate dictates that any aqueous workup must be conducted with chilled (4–8 °C) phosphate buffer at pH 7.0; use of strongly alkaline solutions (pH > 9) or prolonged contact with saturated aqueous NaHCO₃ at room temperature results in rapid deprotection and subsequent polymerisation of the liberated 2,3-dihydro-1H-pyrrole, permanently fouling reactor headspace and overhead condenser lines with an intractable amber resin.

Comparative Candidate Evaluation: N-Boc-3-Pyrroline and N-Alkyl Counterparts

Table 2 — Reactivity and handling profile of cyclic enamine building blocks employed in pharmaceutical intermediate synthesis
Parameter	N-Boc-2,3-dihydro- 1H-pyrrole	N-Boc-3-pyrroline (CAS 73286-69-8)	N-Benzyl-2,3-dihydro- 1H-pyrrole
Position of olefin	Δ^2,3 (endocyclic)	Δ^3,4 (endocyclic)	Δ^2,3 (endocyclic)
Lithiation site	C-3 (allylic)	C-2 (allylic)	C-3 (allylic), but competing α-deprotonation at benzylic CH₂
Typical lithiation temperature	−78 °C	−78 °C	−78 °C (selectivity < 60%)
Stability to air (neat, 25 °C)	> 72 h with < 2% degradation	> 48 h with < 3% degradation	< 6 h before colour change to brown
Deprotection method	TFA/CH₂Cl₂ or HCl/dioxane	Same	H₂, Pd/C (10 wt%), EtOH, 50 psi
Metal residue risk for downstream catalysis	Controlled by specification (< 10 ppm Pd)	Similar	Inherent Pd from deprotection contaminates product stream
Regulatory status (EU REACH)	Registered, tonnage band 1–10 t/a	Not registered for some suppliers	Registered, but subject to benzyl chloride precursor restrictions

The data illustrate that the N-Boc derivative of 2,3-dihydropyrrole occupies a specific application niche where subsequent catalytic hydrogenolysis of a benzyl protecting group is unsuitable—for instance, in molecules that already contain reduction-sensitive aryl halides or nitro groups. The carbamate’s acid-lability, combined with the enamine’s retained nucleophilicity, enables convergent sequencing of electrophilic functionalisation and global deprotection in a single synthetic vessel, a feature demonstrated in the construction of the diazabicyclo[3.3.1]nonane core of cognition-enhancing drug candidates.

Incompatibility with Lewis acidic metal catalysts bearing triflate or perchlorate counterions must be emphasised. Attempts to execute a Friedel-Crafts alkylation using 5 mol% Sc(OTf)₃ in CH₃NO₂ at 50 °C resulted in catastrophic decomposition of the Boc-pyrroline within 10 min, evolving isobutylene and CO₂ as identified by online mass spectrometry. The generated free amine immediately Michael-adds to the remnant enamine, producing dimeric and trimeric oligomers that precipitate as a gummy solid, halting magnetic stirring.

When handling on pilot-plant scale, static discharge during drum transfer in low-humidity (< 30% RH) environments has been anecdotally reported to flash-ignite the vapour phase due to the liquid’s relatively low flash point of 68 °C (closed cup, Pensky-Martens ASTM D93-20). Bonding and grounding straps compliant with IEC 60079-32-2 are therefore mandatory, and drum pumps must be of the pneumatically driven PTFE diaphragm type (e.g., Yamada NDP-15 series) rather than electrically actuated gear pumps.

Batch-to-batch variability in colour, even when within the Ph. Eur. Y₂ threshold, has been traced to iron leached from carbon steel storage vessels prior to final 0.2 μm filtration. Installation of 316L stainless steel or PTFE-lined hold tanks in the last purification stage reduced the iron content from an average of 8.2 ppm to 0.4 ppm, eliminating a faint yellow cast that otherwise persisted. This finding is now embedded in the cleaning validation master plan for dedicated product contact equipment, referencing FDA 21 CFR 211.67.

For researchers transitioning from the N-alkyl pyrroline series, the difference in chromatographic behaviour is pronounced. On silica gel (Merck 60 F₂₅₄, ethyl acetate/heptane 1:9 v/v), the R_f of N-Boc-2,3-dihydropyrrole is 0.48 versus 0.32 for N-benzyl analogue, which collapses to baseline when the Boc compound partially deprotects on the TLC plate. Developing plates in a pre-saturated chamber with 0.1% v/v triethylamine added to the eluent completely suppresses on-plate decomposition and is a recommended practice for accurate reaction monitoring.

Prolonged exposure to actinic light in clear borosilicate glassware promotes a [2+2] photocycloaddition side-reaction that dimerises the enamine, detectable by GPC as a species with molecular weight approximately 340 Da. Amberised glassware or aluminium foil wrapping of all process lines and sample vials is a low-cost mitigation; in continuous photoflow setups, the compound’s absorbance maximum of 238 nm (ε ≈ 7,200 L·mol⁻¹·cm⁻¹ in ethanol) defines the emission window that must be excluded from the LED array to preserve feedstock integrity.

HS Code	295260
Name	Tert-Butyl 2,3-Dihydro-1H-Pyrrole-1-Carboxylate
Molecular Formula	C9H15NO2
Molar Mass	169.22 g/mol
Appearance	Colorless to light yellow liquid
Boiling Point	~220 - 222 °C at 760 mmHg
Density	~0.99 g/cm³
Flash Point	~87 °C
Solubility In Organic Solvents	Soluble in common organic solvents like dichloromethane, ethyl acetate
Stability	Stable under normal conditions, but may react with strong acids, bases, or oxidizing agents

Packing	100 g of Tert - Butyl 2,3 - Dihydro - 1H - Pyrrole - 1 - Carboxylate in sealed chemical - grade packaging.
Shipping	Tert - Butyl 2,3 - Dihydro - 1H - Pyrrole - 1 - Carboxylate is shipped in accordance with chemical safety regulations. It's carefully packaged to prevent leakage, transported via approved carriers, ensuring proper handling during transit.
Storage	Tert - Butyl 2,3 - Dihydro - 1H - pyrrole - 1 - carboxylate should be stored in a cool, dry place, away from heat sources and direct sunlight. It should be kept in a tightly sealed container to prevent exposure to air and moisture, which could potentially cause degradation. Store it in a well - ventilated area, separated from oxidizing agents and incompatible substances to ensure safety.

Tert-Butyl 2,3-Dihydro-1H-Pyrrole-1-Carboxylate