This compound belongs to the class of organic compounds known as furopyridines. These are aromatic heterocyclic compounds containing a furopyridine ring system, which consists of a furan ring fused to a pyridine ring.
External Descriptors
Not available
1. Djoumbou Feunang Y, Eisner R, Knox C, Chepelev L, Hastings J, Owen G, Fahy E, Steinbeck C, Subramanian S, Bolton E, Greiner R, and Wishart DS. ClassyFire: Automated Chemical Classification With A Comprehensive, Computable Taxonomy. Journal of Cheminformatics, 2016, 8:61.
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Application Protocols
Not applicable to this product type.
Tested applications (e.g., WB, IHC, IF, FC), recommended dilutions, and positive controls: Not specified for this item; this is a small-molecule building block supplied for chemical synthesis and research use only.
For synthetic procedures, refer to the Reaction Conditions and Synthetic Utility sections for literature-style guidance.
Biological Roles
Item-specific biological data: Not specified for this item; no biological activity claims are made. For research use only.
General chemistry/biochemistry context (literature)
Fused N/O‑heteroarenes (e.g., furo[3,2‑b]pyridines) are common scaffolds in chemical biology and medicinal chemistry due to their planarity, hydrogen-bond acceptors (ring N, ring O), and tunable electronics. They can serve as bioisosteres for bicyclic aromatics, modulating π–stacking, dipole interactions, and metabolic stability.
Terminal alkynes are versatile reporter handles: they undergo copper‑catalyzed azide–alkyne cycloaddition (CuAAC), enabling bioconjugation to probes, affinity tags, or surfaces. Although this compound is not supplied as a biological reagent, its alkyne could, in principle, be leveraged as a synthetic intermediate en route to tagged molecules.
Physicochemical profile: Neutral, moderately aromatic, and relatively compact (computed formula C9H5NO), suggesting potential for membrane permeability when embedded in larger constructs; however, solubility in aqueous media is expected to be low without ionizable groups or polar substituents.
No claims are made regarding cellular targets, potency, or pharmacology of this specific compound. Any use in biological systems should be preceded by derivatization, formulation, and appropriate safety/compatibility testing.
Buffer Applications
This compound is a neutral, sparingly water-soluble heteroaryl alkyne and is not typically used as a buffering agent or buffer component.
Not typically applicable
It lacks acid/base functionality suitable for maintaining a stable pH in aqueous systems.
Practical note
If used in biochemical workflows (e.g., as a synthetic intermediate for probes), dissolve in an appropriate organic co-solvent (DMSO, DMF, MeCN) before dilution into aqueous buffers, ensuring the final co-solvent content is compatible with the system.
Green Alternatives
Selecting greener conditions with this heteroaryl alkyne focuses on solvent and catalyst systems rather than changing the substrate.
Solvent choices (literature guidance)
Replace chlorinated solvents (DCM) with ethyl acetate, 2‑MeTHF, CPME, or toluene where feasible.
For click chemistry, water/t‑BuOH (1:1) or water/ethanol can reduce VOC burden while maintaining performance.
Catalysis and bases
Copper-free Sonogashira (Pd only) minimizes copper waste and Glaser-type homocoupling byproducts; employ phosphine-ligated Pd in greener solvents (e.g., 2‑MeTHF, propylene carbonate) with organic bases (Et3N, DBU).
Heterogeneous catalysts (Pd/C, Pd on green supports) may simplify recovery/reuse; assess leaching for sensitive applications.
Energy and work-up
Microwave or flow chemistry can shorten reaction times and improve selectivity, reducing solvent and energy consumption.
Use aqueous biphasic extraction with eco-friendly solvents (EtOAc) and minimize silica by employing crystallization or plug filtration when possible.
Example comparison (general)
Traditional: Sonogashira in DMF/Et3N, 60–80 °C, Pd(PPh3)2Cl2/CuI.
Greener alternative: Sonogashira in 2‑MeTHF or EtOAc with Pd/C or Pd‑NHC, DIPEA, 40–60 °C; copper-free.
These alternatives are literature-based best practices; confirm compatibility with this substrate on small scale before scale-up.
Pharmaceutical Uses
Item-specific pharmacopeial status/excipient role: Not specified for this item; no compendial listings indicated. For research use only.
General formulation/manufacturing context (literature)
Heteroaryl acetylenes like 6‑ethynylfuro[3,2‑b]pyridine are primarily synthetic intermediates in medicinal chemistry, enabling construction of structure–activity libraries via Sonogashira coupling or click reactions. They are not typical pharmaceutical excipients.
If incorporated into discovery programs, compounds of this class are handled as drug-substance intermediates under R&D quality systems. Typical controls include identity (NMR/HRMS), purity by HPLC, and residual palladium/copper testing post-coupling where relevant.
For screening collections, solutions are often prepared in DMSO at known concentrations (e.g., 10–50 mM) and stored at low temperature to mitigate degradation. For this specific item, solution stability parameters are not specified and should be determined empirically.
No therapeutic or clinical claims are made for this product.
Physical Properties
Item-specific specifications are not provided in the Product Data. The following values are general literature/computed information for the scaffold and closely related analogs; do not treat as product specifications.
Item-specific properties
Appearance: Not specified for this item; refer to CoA/Spec Sheet.
Grade/Purity: Not specified for this item; refer to CoA/Spec Sheet.
Molecular formula: Not specified for this item; refer to CoA/Spec Sheet.
Molecular weight: Not specified for this item; refer to CoA/Spec Sheet.
Literature/computed (for 6‑ethynylfuro[3,2‑b]pyridine or close analogs)
Estimated molecular formula: C9H5NO (computed from structure).
Lipophilicity: heteroaryl acetylene typically shows moderate aromatic character with low–moderate polarity; cLogP often ~1–2 for related furo[3,2‑b]pyridines (literature trend; specific value not available for this item).
Ionization: lacks obvious ionizable groups in neutral water; ring N is basic only weakly when fused and deactivated; behaves neutral under most conditions (general heteroaromatic behavior).
Solubility profile: typically soluble in common organic solvents (e.g., DCM, EtOAc, THF, acetone, toluene, MeCN) and poorly soluble in water (literature/experience with analogous heteroaryl acetylenes). Quantitative solubilities are not available for this item.
Physical state: many heteroaryl acetylenes are low-melting solids or high-boiling oils; specific MP/BP for this item: Not specified for this item; refer to CoA/Spec Sheet.
Always confirm critical parameters (MP, purity, water content, residual solvents) from the item’s CoA prior to use in specifications-sensitive applications.
Quality and Grades
Item-specific quality information
Grade/Purity: Not specified for this item; refer to CoA/Spec Sheet.
Stabilizers/Inhibitors: Not specified for this item; refer to CoA/Spec Sheet.
Interpreting grades (general guidance)
Research grade: Common for heteroaryl building blocks; suitable for discovery chemistry and process development. Purity typically reported by HPLC/GC and 1H NMR assay; residual solvent and water by GC/KF. If the application involves photophysics or trace-catalyst development, request an extended specification (UV cutoff, metal content) where relevant.
Screening/medchem grade: Emphasis on identity/purity for library synthesis; may not include stringent residual metals or trace peroxide specifications.
High-purity (≥98–99%) variants: Useful for kinetic studies or structure–activity investigations where impurity profiles affect outcomes.
Analytical notes for this scaffold (general)
Identity confirmation: 1H/13C NMR should show an acetylenic proton near δ ~3.0–3.5 ppm (often broad/weak) and sp carbons around δ ~80–90/100–110 ppm; heteroaromatic protons distributed δ ~6.5–9.0 ppm. HRMS [M+H]+ expected at m/z ~144.044 (from computed formula C9H6NO+).
Purity assessment: HPLC with UV detection at 220–280 nm is effective; terminal alkyne often exhibits strong response at lower wavelengths.
For critical projects, confirm the supplied batch’s actual specifications (purity assay method, residual solvents, moisture, and any stabilizers) from the CoA.
Reaction and Applications
As a terminal alkyne embedded on an electron-deficient furo[3,2‑b]pyridine, this building block enables diversified C–C and C–X bond construction and heterocycle elaboration.
Coupling chemistry (literature)
Sonogashira coupling: Couples with aryl/vinyl halides or triflates (Pd^0, CuI co-catalyst; amine base) to deliver internal diynes/aryl‑alkynes substituted on the furo[3,2‑b]pyridine core.
Cadiot–Chodkiewicz/Glaser variants: Oxidative homocoupling to diynes under Cu/O2; or cross-coupling with haloalkynes (Cadiot–Chodkiewicz) to access conjugated diynes.
Cycloadditions and annulations (literature)
CuAAC click reaction: Formation of 1,4‑disubstituted 1,2,3‑triazoles with organic azides (Cu(I) catalysis). The heteroaryl ring can modulate electronic properties of the triazole products.
[2+2+2] or Ru/Co-catalyzed annulations: Terminal alkyne as a partner in alkyne–nitrile or alkyne–diyne cyclizations to forge polycyclic N/O-heteroarenes.
Nucleophilic acetylide chemistry (literature)
Deprotonation (pKa of terminal alkyne ~25 in DMSO, general) affords the corresponding acetylide, enabling additions to carbonyls or SN2 substitutions on activated electrophiles.
Heteroaromatic reactivity (literature)
The ring nitrogen and oxygen can direct metalation (e.g., ortho‑lithiation relative to N/O) under strong bases, allowing further functionalization remote from the alkyne.
Practical tips
Ensure anhydrous conditions for metalation/coupling; pre-dry by azeotrope or store over 3 Å molecular sieves if preparing stock solutions.
For Pd/Cu couplings, degas solvents and consider amine bases that also serve as solvent (Et3N, i‑Pr2NH) to improve rate.
Reaction Conditions
The following are literature-style general conditions for common transformations of terminal arylacetylenes and should be optimized for this substrate.
Sonogashira coupling (to form internal arylalkynes)
Typical: Aryl/vinyl halide (1.0 eq), terminal alkyne (1.2–1.5 eq), Pd(PPh3)2Cl2 (1–3 mol%), CuI (2–5 mol%), Et3N or i‑Pr2NH (2–3 eq or as solvent), 50–80 °C, 2–12 h, N2. Copper-free variants use Pd(0)–NHC or Pd2(dba)3/XPhos in amine or 2‑MeTHF/DIPEA.
CuAAC click reaction (to form 1,4‑disubstituted triazoles)
Typical: Azide (1.0 eq), alkyne (1.0–1.2 eq), CuSO4·5H2O (1–5 mol%) + sodium ascorbate (5–10 mol%) in t‑BuOH/H2O (1:1) or DMSO/H2O, rt–60 °C, 0.5–12 h. Cu(I) sources like CuI/ligand can accelerate at rt.
Glaser oxidative homocoupling (to diynes)
Typical: CuI (5–10 mol%), amine base (Et3N/pyridine), O2 or air, solvent such as DMF/THF, rt–60 °C, 2–16 h.
Acetylide formation/alkylation
Typical: n‑BuLi or LDA (1.1–1.2 eq) in dry THF or toluene at −78 to 0 °C under N2, then add electrophile (alkyl halide, carbonyl). Quench and warm to rt. Caution: strong bases and low temperatures required to control selectivity.
Hydrogenation/semi-hydrogenation
Typical: H2 (1–3 bar), Lindlar catalyst for Z‑alkenyl products at rt–25 °C; or Pd/C for full saturation at rt–40 °C.
Yields vary widely (40–90%+) depending on substrates/ligands. Start with small-scale screens and adjust catalyst/ligand/base to the heteroaryl electronics of furo[3,2‑b]pyridine.
Safety and Handling
Item-specific safety classification
GHS classification, signal word, pictograms, and H-statements: Not specified for this item; consult the SDS for authoritative information.
General safety considerations (literature/general guidance for heteroaryl terminal alkynes)
Hazards: May cause irritation to skin, eyes, and respiratory tract. Terminal alkynes and aromatic heterocycles are typically combustible; treat as a flammable organic compound. Avoid inhalation of vapors or dust.
Peroxide formation: Terminal alkynes are not classic peroxide-forming like ethers, but all unsaturated organics should be stored away from strong oxidizers; periodically inspect aged material.
Incompatibilities: Strong oxidizing agents, strong acids/bases (can induce polymerization/side reactions), and reactive metals/bases in the presence of moisture (may deprotonate the alkyne).
Recommended PPE and handling
Use in a fume hood with appropriate local exhaust.
Wear safety glasses or splash goggles, lab coat, and compatible chemical-resistant gloves (e.g., nitrile). Avoid skin contact and inhalation of aerosols/dust.
Avoid ignition sources; ground containers when transferring flammable solvents.
First-aid overview (general)
Inhalation: Move to fresh air; seek medical attention if symptoms persist.
Skin/eye contact: Rinse with water for ≥15 minutes; remove contaminated clothing; seek medical attention for persistent irritation.
Ingestion: Rinse mouth; do not induce vomiting; seek medical attention.
Always refer to the product-specific SDS before use for definitive hazards, exposure controls, and spill/firefighting guidance.
Solvent Selection
This compound is a neutral, moderately polar heteroaryl terminal alkyne. Solvent choice depends on the intended transformation (coupling, cycloaddition, deprotonation) and on handling considerations.
General miscibility/solubility (literature-based for heteroaryl acetylenes)
Poor: water and highly protic, very polar media without co-solvent.
Selection by application
Cross-coupling (Sonogashira): DMF, DMAc, DMSO, MeCN, or THF/toluene are common. Include a base (e.g., Et3N, DIPEA) as solvent or co-solvent when appropriate.
CuAAC (“click”): t‑BuOH/H2O or MeOH/H2O mixtures are typical; use a water-miscible co-solvent if solubility is limited.
Deprotonation/alkylation: Anhydrous THF or toluene under inert atmosphere with strong bases (e.g., LDA, n‑BuLi) enable formation of the acetylide.
Practical considerations
Heteroatoms (N, O) in the ring can coordinate to catalysts; polar aprotic solvents often enhance catalyst solubility and turnover.
If chromatography is expected, choose solvents that minimize tailing for polar heteroaromatics (e.g., EtOAc/hexanes with small % of Et3N to suppress adsorption if needed).
Small comparison (literature trend)
THF: good balance of solubility and basicity handling; peroxide risk on storage (solvent-specific).
MeCN: excellent for Pd/Cu catalysis and easy removal; lower solubility for some scaffolds.
Toluene: high boiling for elevated-temperature couplings; may require polar co-solvent for full dissolution.
Storage and Reconstitution
Item-specific storage and shipping
Storage conditions: Room temperature (as provided in Product Data). Protect from light and moisture for best stability.
Shipped in: Normal conditions (as provided).
Stability notes (general guidance for heteroaryl acetylenes)
Store tightly closed under inert gas if possible to minimize oxidation or polymerization under harsh conditions; keep away from strong acids/bases and oxidants.
If preparing solutions, use dry, oxygen-free solvents (e.g., anhydrous DCM, THF, MeCN) and store at low temperature (e.g., 2–8 °C or −20 °C) in amber vials to mitigate degradation. Solution stability is substrate- and solvent-dependent; verify by HPLC before reuse.
Reconstitution and handling
Appearance: Not specified for this item; refer to CoA/Spec Sheet.
Dissolution: Typically dissolves in common organic solvents (DCM, THF, EtOAc, MeCN, DMF, DMSO). Sonication or mild warming may assist dissolution; avoid prolonged heating.
Drying: If needed, dry under high vacuum at ambient temperature. Avoid strong heat to prevent decomposition of the alkyne functionality.
Always consult the lot-specific CoA/SDS for definitive storage life, compatibility, and handling instructions.
Structure and Identity
A fused, nitrogen–oxygen heteroaromatic bearing a terminal alkyne at the 6‑position on the furo[3,2‑b]pyridine core.
Item-specific identifiers (from Product Data)
SKU: E166445
Product name: 6‑Ethynylfuro[3,2‑b]pyridine
CAS: 1203499-35-7
PubChem CID: 46737949
InChIKey: 170347 (as provided; note this is not a standard-length InChIKey)
SMILES: Not specified for this item; refer to CoA/Spec Sheet.
Approximate molecular weight: ~143.14 g/mol (computed from formula).
2D structural description (verbal)
A six-atom aromatic segment containing one ring nitrogen is fused to a five-membered oxygen-containing ring; an sp-hybridized C≡C–H extends from the carbon adjacent to the oxygen within the fused framework (position 6), rendering the scaffold an electron-deficient heteroaryl acetylene suitable for further coupling or cycloaddition chemistry.
Synthetic Utility
The 6‑ethynyl substituent on a furo[3,2‑b]pyridine core provides a convergent handle for rapid diversification while preserving the fused heteroaromatic pharmacophore.
Functional group leverage (literature)
Terminal alkyne: participates in Sonogashira couplings (to aryl/vinyl halides), CuAAC click reactions (to azides), hydrofunctionalizations (hydroboration, hydroamination), nucleophilic acetylide chemistry (addition to carbonyls), and oxidative couplings (Glaser, Cadiot–Chodkiewicz).
Heteroaromatic directing elements: ring N/O can influence metal coordination and regioselectivity in C–H activation or lithiation, enabling orthogonal substitutions elsewhere on the ring system.
Retrosynthetic value
The compound can serve as a lynchpin, connecting an electrophilic aryl/vinyl partner and an azide-bearing fragment to assemble triazole-linked libraries, or as a partner in modular assembly of conjugated systems (OLED materials, ligands) via alkyne chemistry.
Downstream transformations (examples, literature)
Hydrogenation to the alkyl derivative (selective semi-hydrogenation to alkenyl stage possible with Lindlar catalyst).
Haloboration/iodination of the alkyne to introduce handle(s) for further cross-coupling.
Gold- or Brønsted acid-catalyzed intramolecular cyclizations when suitably tethered to nucleophiles (design-dependent).
Overall, this scaffold combines a versatile sp‑hybridized handle with an electron-deficient fused ring, making it a practical intermediate for medchem, materials, and heteroarene methodology exploration.
Target Specificity
Not applicable to this product type.
Item-specific biological target, antigen/epitope, clone, isotype, or species reactivity: Not specified for this item; this is a small-molecule building block, not an antibody/biologic.
No claims are made regarding selectivity toward any biological target.
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