5-Bromo-2-Piperidin-1-Yl-1,3-Thiazole

In the multi-kilogram production of a third-generation EGFR tyrosine kinase inhibitor designed to override the T790M gatekeeper mutation, 5-bromo-2-piperidin-1-yl-1,3-thiazole is deployed as the electrophilic coupling partner in a Suzuki-Miyaura cross-coupling step that installs a 4-fluoro-2-methoxyphenyl motif onto the thiazole C5 position. Reaction calorimetry data gathered on a Mettler Toledo RC1mx in 1.2 L reaction volume reveals an adiabatic temperature rise of 38°C at 100% conversion if the dosing of the arylboronic acid solution is not temporally distributed, a finding that directly dictates the selection of a semi-batch protocol with controlled metering over 45 minutes to maintain the internal temperature at 78±2°C. The formulation addition ratio is locked at 1.00 equivalent of 5-bromo-2-piperidin-1-yl-1,3-thiazole to 1.05 equivalent of the boronate ester, with 0.3 mol% Pd(dppf)Cl₂·CH₂Cl₂ and 2.5 equivalent of tribasic potassium phosphate in a degassed dioxane-water mixture; any deviation beyond 1.08 equivalent of the boronate leads to a detectable homocoupling impurity at retention time 11.23 min on a C18 column (USP <621> method) that co-elutes with the desired API precursor during isocratic elution, forcing a rework by preparative HPLC. On the manufacturing floor, a 630 L Hastelloy C-22 reactor equipped with a retreat-curve impeller and a rupture disc rated at 4.2 barg is employed, and failure to initiate jacket cooling within 90 seconds of boronate dosing has been documented to produce a temperature overshoot that increases the 5-desbromo thiazole impurity from 0.4 area% to 2.7 area%, rendering the batch non-conformant to the in-process specification of ≤0.8 area% before charcoal treatment. Industry compliance for this intermediate falls under ICH Q7 Active Pharmaceutical Ingredient GMP guidance, with particular attention to elemental impurity limits per ICH Q3D Table A.2.1 (Class 1 element Pd must be ≤10 ppm) and solvent residues per ICH Q3C (1,4-dioxane capped at 380 ppm). The terminal dosage form is a film-coated immediate-release tablet containing the besylate salt of the kinase inhibitor, manufactured under 21 CFR 211.110 sampling and testing requirements and packaged in Alu-Alu blisters.

Process analytical technology integration during the Suzuki-Miyaura stage has transitioned from offline HPLC to an in-line ReactIR 15 probe with a diamond ATR sensor inserted into the recycle loop of a micro-packed bed reactor. In a Corning Advanced-Flow G1 SiC module, the reaction proceeds with a mean residence time of 47 seconds at 145°C and 5.5 bar back pressure, achieving full conversion with a palladium inventory reduced to 0.08 mol% when the aqueous phosphate base is preheated to 80°C before merging with the organic stream. The microchannel configuration suppresses the thermal runaway scenario by maintaining a volumetric heat transfer coefficient consistently above 1,800 W/m²·K, compared to 320 W/m²·K in a jacketed batch vessel, thereby eliminating the hot spots that previously triggered debromination. Scale-up from the G1 to the G4 module with 250 mL internal volume sustains a throughput of 13.2 kg/day of the thiazole intermediate, verified by LC-MS quantification at m/z 274.9/276.9 [M+H]+. During a technology transfer to a CDMO in Visakhapatnam, India, a batch-to-batch variance of less than 1.2% in isolated yield over seventeen consecutive campaigns was realized only after replacing the atmospheric nitrogen inerting with a sparging regime of 0.2 vvm argon to eliminate oxidative phosphine ligand degradation that had previously caused Pd black precipitation and reactor fouling on the heat-exchange surfaces.

What necessitates a cryogenic lithiation strategy for Buchwald-Hartwig sequences on the thiazole scaffold?

When 5-bromo-2-piperidin-1-yl-1,3-thiazole is utilized to introduce a 3-chloro-4-(pyridin-2-ylmethoxy)aniline fragment en route to a D2/D3 receptor partial agonist antipsychotic candidate, the inherent reactivity of the C-Br bond demands a non-conventional halogen-metal exchange prior to amination to circumvent direct C-N bond formation at the 2-piperidinyl position. The addition ratio applied in the discovery synthesis calls for 0.98 equivalent of n-butyllithium at -78°C in anhydrous THF under a rigorously maintained Karl Fischer titration limit of ≤50 ppm water, generating the lithiated thiazole species which is then transmetalated with ZnCl₂ (1.2 equivalent) to form an organozinc intermediate suitable for Pd₂(dba)₃ (0.5 mol%) / XPhos (1.2 mol%) catalyzed coupling with the aryl bromide. Downstream manufacturing in a 160 L pilot-plant cryogenic reactor equipped with a liquid nitrogen jacket and a Fauske & Associates calorimeter verified that the lithium-halogen exchange exhibits a heat flow rate of 85 W/kg at the point of addition, necessitating a dosing rate of 3.2 kg/h of BuLi solution to keep the internal temperature below -72°C. Industry compliance for this intermediate stage adheres to ICH M7 (R1) for mutagenic impurity control, requiring Ames testing data for the 2-piperidinyl thiazole aldehyde oxidative impurity that forms if the lithiated intermediate is quenched with trace oxygen; batches intended for Phase III clinical material are subjected to a confirmatory LC-HRMS screen with a reporting threshold of 15 ppm for the aldehyde. The terminal product is formulated as an orodispersible tablet meeting Ph. Eur. 10.0 monograph 0478 disintegration criteria, with the API particle size d90 controlled below 30 µm by jet milling to ensure mouthfeel acceptability.

For an agrochemical fungicide active against QoI-resistant strains of Zymoseptoria tritici, the thiazole intermediate is transformed into a pyrazole-4-carboxamide via a carbonylative amidation sequence using 1.05 equivalent of 5-bromo-2-piperidin-1-yl-1,3-thiazole, molybdenum hexacarbonyl as a solid CO source, and a Pd(dppf)Cl₂ catalyst system in a pressure vessel rated at 12 bar. The addition ratio must be precisely maintained because transcarbonylative coupling side products, identifiable by their characteristic 1745 cm⁻¹ IR band, exceed 0.5 area% when the thiazole to molybdenum reagent molar ratio falls below 1.00:0.95. Crystallization of the final technical-grade active ingredient from a 2-propanol/water (75:25 v/v) mixture under controlled cooling from 65°C to 5°C at 0.2°C/min is critical to obtain the thermodynamically stable Form I polymorph, as the metastable Form II that precipitates at cooling rates exceeding 0.5°C/min is prone to Ostwald ripening during suspension concentrate storage, leading to crystal growth beyond the 5 µm D50 specification which compromises nozzle sprayability. Regulatory compliance for this supply chain is governed by the OECD GLP Principles as recognized under EC 1107/2009 Annex II, requiring a five-batch analysis for the technical active with impurity profiling performed according to SANCO/10597/2003 rev. 10.1; residual palladium is limited to ≤5 ppm in the purified active, and 1,4-dioxane is restricted to ≤50 ppm by GC-FID headspace per CIPAC MT 184. The formulated end product is a 500 g/L suspension concentrate containing a tristyrylphenol ethoxylate surfactant system, a negatively charged polycarboxylate dispersant to achieve a yield stress value of 0.8 Pa, and a xanthan gum rheology modifier providing a high-shear viscosity of 55 mPa·s at 10,000 s⁻¹, compatibilized for tank-mix use with triazole fungicides.

In a parallel agrochemical supply stream targeting two-spotted spider mite (Tetranychus urticae) populations resistant to METI acaricides, the thiazole scaffold participates in a copper-mediated ulmann-type C-S bond formation where 5-bromo-2-piperidin-1-yl-1,3-thiazole is reacted with a 4-tert-butylbenzenethiol at a molar ratio of 1.00:1.15 in the presence of CuI (12 mol%) and 1,10-phenanthroline (15 mol%) in dimethylacetamide at 110°C. The thiolate coupling process must be executed under a nitrogen-purged environment because oxygen ingress above 0.5% in the headspace accelerates disulfide formation, which partitions into the product stream and requires an additional charcoal treatment that reduces isolated yield by 9-11%. Compliance for this early-stage intermediate destined for non-food uses follows the FAO/WHO Manual on development and use of pesticide specifications (March 2022 revision), with emphasis on the batch-to-batch identity confirmation by external standard ¹H NMR integration of the piperidine axial proton resonance at δ 3.42 ppm referenced to 1,3,5-trimethoxybenzene internal standard. The terminal product is an emulsifiable concentrate (EC) formulation containing 180 g/L of the active diaryl sulfide derivative, dissolved in a mixture of Solvesso 200 ND and γ-butyrolactone with an anionic-nonionic emulsifier blend providing an emulsion stability score of ≥4 mL cream phase after 24 h in CIPAC Standard Water A.

Thiazole–piperidine donor–acceptor motifs for non-fullerene acceptors—purity thresholds for bulk-heterojunction inks

In the synthesis of a narrow-bandgap non-fullerene acceptor featuring an indacenodithiophene core end-capped with 2-(piperidin-1-yl)thiazole electron-withdrawing groups, 5-bromo-2-piperidin-1-yl-1,3-thiazole is subjected to a direct arylation polymerization-compatible coupling with a dibromo-indacenodithiophene monomer using a Herrmann-Beller palladacycle catalyst (2 mol%) and pivalic acid additive (30 mol%) in toluene at 105°C. The stoichiometric ratio of the thiazole monomer to the core monomer is set at 1.000:1.005 to ensure bromine-terminated chain ends, as observed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry showing an end-group mass series of [M+H]+ at m/z 1,875.4 through 2,347.8 for the trimer and tetramer species. Fabrication of the active layer utilizing a slot-die coater at 3 m/min web speed required that the acceptor fraction be additionally purified by temperature-gradient sublimation at 240°C and 6.2×10⁻⁶ mbar to reduce non-volatile residue below 0.03 wt%, a purity metric that directly correlates with a reduction in the dark leakage current from 1.8×10⁻⁷ A/cm² to 3.2×10⁻⁹ A/cm² at -1 V in a ITO/PEDOT:PSS/active layer/LiF/Al inverted device architecture. The material supplier qualification follows certified testing aligned with IEC 62930:2017 clauses 5.2 and 6.3 for insulating substrate photovoltaics, while the halogen content is verified by combustion ion chromatography against an external Br⁻ standard traceable to NIST SRM 3183. The terminal product is a flexible organic photovoltaic module encapsulated with a multilayer barrier film having a water vapor transmission rate below 10⁻⁴ g/m²/day and a fill factor maintained at 0.72 after 1,000 h of damp-heat aging at 85°C/85% RH.

When the Sonogashira cross-coupling protocol is employed to attach a cyclopropylacetylene moiety generating a non-nucleoside reverse transcriptase inhibitor (NNRTI) active against the K103N mutant variant, the reaction stoichiometry is maintained at 1.00 equivalent of 5-bromo-2-piperidin-1-yl-1,3-thiazole and 1.10 equivalent of the terminal alkyne using 3 mol% Pd(PPh₃)₄ and 5 mol% CuI in triethylamine at 55°C. The downstream workup includes an aqueous ammonium chloride quench followed by extraction with methyl tert-butyl ether and a silica plug filtration through a 10 µm porosity frit to scavenge residual copper; a multi-client contract manufacturing organization in Lonza’s Visp facility has implemented an inline ExtractionTek LLE unit that reduces the aqueous/organic phase separation time from 45 minutes to 6 minutes by maintaining a 0.3 MPa pressure differential across a fluoropolymer membrane. The formulated drug product is an opaque hard gelatin capsule containing a spray-dried dispersion of the NNRTI with copovidone VA64 (30% w/w drug loading) exhibiting a glass transition temperature of 108°C by modulated DSC, stored per ICH Q1A (R2) stability conditions at 25°C/60% RH with a 24-month retest period.