3-Ethynylpyridine-2,6-diamine - ≥95% , CAS No.936342-42-6

CAS: 936342-42-6 Cat. No.: E963659 Formula: C₇H₇N₃ Peso molecolare: 133.150

GRADE & PURITY ≥95%

Storage

Room temperature

Specifications

Specifiche e purezza

≥95%

Condizioni di conservazione di stoccaggio

Room temperature

Purezza

≥95%

Nomi e identificatori

• Sorrisi canonici: C#CC1=C(N=C(C=C1)N)N
• IUPAC Name: 3-ethynylpyridine-2,6-diamine
• InChIKey: AAJLWBCLZSGCPA-UHFFFAOYSA-N
• INCHI: 1S/C7H7N3/c1-2-5-3-4-6(8)10-7(5)9/h1,3-4H,(H4,8,9,10)
• Peso molecolare: 133.150

Taxonomic Classification

Taxonomy Tree

• Kingdom Organic compounds
  • Superclass Organoheterocyclic compounds
    • Classe Pyridines and derivatives
      • Subclass Aminopyridines and derivatives

• Kingdom: Organic compounds
• Superclass: Organoheterocyclic compounds
• Classe: Pyridines and derivatives
• Subclass: Aminopyridines and derivatives
• Intermediate Tree Nodes: Not available
• Direct Parent: Aminopyridines and derivatives
• Alternative Parents: Imidolactams Heteroaromatic compounds Azacyclic compounds Acetylides Primary amines Hydrocarbon derivatives
• Molecular Framework: Aromatic heteromonocyclic compounds
• Substituents: Aminopyridine - Imidolactam - Heteroaromatic compound - Acetylide - Azacycle - Organic nitrogen compound - Hydrocarbon derivative - Primary amine - Organonitrogen compound - Amine - Aromatic heteromonocyclic compound
• Descrizione: This compound belongs to the class of organic compounds known as aminopyridines and derivatives. These are organic heterocyclic compounds containing an amino group attached to a pyridine ring.
• External Descriptors: Not available

Data sources

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.

DOI: 10.1186/s13321-016-0174-y

Proprietà chimiche e fisiche

• Peso molecolare: 133.150 g/mol
• XLogP3: 0.400
• Hydrogen Bond Donor Count: 2
• Hydrogen Bond Acceptor Count: 3
• Rotatable Bond Count: 1
• Exact Mass: 133.064 Da
• Monoisotopic Mass: 133.064 Da
• Topological Polar Surface Area: 64.900 Ų
• Heavy Atom Count: 10
• Formal Charge: 0
• Complexity: 157.000
• Isotope Atom Count: 0
• Defined Atom Stereocenter Count: 0
• Undefined Atom Stereocenter Count: 0
• Defined Bond Stereocenter Count: 0
• Undefined Bond Stereocenter Count: 0
• The total count of all stereochemical bonds: 0
• Covalently-Bonded Unit Count: 1

Application Protocols

No vendor-validated application protocols are provided for this item.

General laboratory usage examples (literature-informed; not product-specific):

• CuAAC bioconjugation: Dissolve the compound (e.g., 10–50 mM) in DMSO. To a solution of azide-tagged partner in tBuOH/H2O (1:1) add CuSO4 (1–2 mol%), sodium ascorbate (2–4 equiv vs Cu), and TBTA ligand (2–4 mol%). Add the alkyne solution dropwise, stir at 25–40 °C until LC–MS shows completion, then quench with EDTA and purify.
• Selective mono-acylation: Protect one amine as Boc, then couple the free amine with an acid (HATU/DIPEA, DMF, rt). Deprotect Boc with TFA/DCM at 0–25 °C and proceed to second diversification.

For step-by-step, product-specific SOPs, consult your internal method development or literature precedents targeting similar pyridine-diamine alkynes.

Biological Roles

Item-specific biological roles are not assigned; this product is for research use only.

General context (literature, not product-specific):

• Heteroaromatic diamines and pyridine-containing scaffolds frequently serve as ligands for metalloenzymes in biochemical studies or as recognition elements in synthetic receptors due to multiple basic sites (pyridine N and –NH2 groups).
• The terminal alkyne enables bioconjugation via CuAAC to attach the pyridyl-diamine motif to biomolecules (e.g., azide-labeled peptides, glycans), facilitating probe synthesis or surface functionalization in chemical biology workflows.
• Protonation states strongly influence binding and solubility in aqueous buffers; under acidic conditions, pyridinium/arylaminium forms increase water compatibility but may reduce membrane permeability.

No endogenous metabolic or signaling role is known for this specific compound.

Buffer Applications

This compound is not a conventional biological buffer. However, its basic nitrogens allow pH-dependent solubility control for handling in aqueous systems.

Practical notes (general):

• To dissolve for bioconjugation (e.g., CuAAC), prepare a stock in DMSO and dilute into a buffered aqueous medium (phosphate, HEPES) containing a small percentage of co-solvent. Alternatively, pre-form the hydrochloride salt to enhance water solubility.
• Avoid strong basic buffers in copper-catalyzed reactions as polyamines can chelate copper; add appropriate ligands and adjust pH (often 7–8) to balance reactivity and metal speciation.

If a true buffering system is required, use established buffers (PBS, HEPES, MOPS); do not rely on this compound for buffering capacity.

Green Alternatives

Greener practice focuses on solvent and reagent selection around this multifunctional scaffold rather than replacing the scaffold itself.

• Greener solvent choices (literature guidance):

  • Replace DMF/DMSO with 2-MeTHF, CPME, or bio-ethanol where solubility and reactivity permit.
  • Use water/ethanol or tBuOH/H2O mixtures for CuAAC; many click reactions proceed efficiently in aqueous media.

• Catalysis and bases:

  • Employ ligand-enabled, low-Pd Sonogashira conditions or copper-free variants to reduce metal load. Explore nickel catalysis where appropriate.
  • Use organic bases (e.g., DBU, DIPEA) in greener solvents to avoid inorganic salt waste.

• Workup/waste minimization:

  • Capitalize on acid/base switching to avoid silica-intensive chromatography (crystallize as salts or free base).
  • Implement metal scavengers and aqueous chelation to reduce residual metal.

Comparison (typical, literature-based):

• CuAAC in tBuOH/H2O: High atom economy, mild, minimal solvent hazard.
• Sonogashira in 2-MeTHF with Et3N: Lower solvent toxicity vs DMF; simpler removal.
• Polar aprotics (DMF/NMP): Excellent solubility but EHS concerns and difficult removal.

Trade-offs: Greener media may reduce substrate solubility; modest heating or co-solvents (EtOH/H2O + small DMSO) can balance EHS and performance.

Pharmaceutical Uses

No pharmacopeial or excipient status is indicated for this item. Not for human or veterinary use.

R&D context (general, not product-specific):

• As a heteroaromatic, polybasic scaffold, 3-ethynylpyridine-2,6-diamine may serve as a synthetic intermediate or fragment in medicinal chemistry programs. The terminal alkyne offers an efficient handle for SAR diversification (e.g., triazole formation via CuAAC), while the diamine can be derivatized to amides, sulfonamides, or carbamates to modulate physicochemical properties.
• For preclinical formulation studies, salt screening (e.g., HCl, mesylate) may be explored to improve solubility and solid-state properties of derivatives; such activities are outside the scope of this catalog listing.

All uses are confined to laboratory research and process development.

Physical Properties

• Item-specific specifications: Not specified for this item; refer to CoA/Spec Sheet.

• Literature/computed (general guidance; not item specifications):

  • Aggregate physical data for this exact compound are limited in open literature. As a small heteroaromatic diamine with a terminal alkyne, it is expected to be a low–to–moderate melting solid with modest volatility.
  • Acid–base properties: The ring nitrogen and two –NH2 groups confer basicity; protonation can enhance aqueous solubility under acidic conditions. Typical pKa values for related 2,6-diaminopyridines: conjugate acid of ring N ca. 5–6; anilinium-type –NH2 groups often pKaH 3–5 (literature, family values). Exact pKa for this compound is not well-documented.
  • Solubility tendencies (literature/experience with similar scaffolds):
    • Likely soluble in polar aprotic solvents (DMF, DMSO, NMP) and alcohols.
    • Limited solubility expected in nonpolar hydrocarbons; solubility may improve upon salt formation in aqueous media (e.g., HCl salt).
  • LogP: Not widely reported; related 2,6-diaminopyridines are moderately polar (cLogP typically <1). Terminal alkyne contributes slight hydrophobicity.
  • Refractive index, density, UV cutoffs: Not widely reported for this exact solid; aromatic absorption expected in near-UV due to pyridine and alkyne chromophores.

Note: For definitive values (mp, elemental analysis, water, metals, UV profile), consult the item’s CoA/Spec Sheet.

Quality and Grades

• Item-specific grade/purity: Not specified for this item; refer to CoA/Spec Sheet.
• Appearance: Not specified for this item; refer to CoA/Spec Sheet.

Context for professionals:

• Research grade heteroaromatic building blocks are typically qualified by NMR (1H/13C), HRMS, and HPLC/GC purity. If low-metal content or residual solvent limits are critical (e.g., for catalysis or analytical applications), request detailed CoA.
• UV profile/low-UV grades (for chromatographic uses) and trace-metal specifications may be available upon request for certain catalogs; absent explicit statements, do not assume such specifications.
• Stabilizers: None indicated. If stabilizers or salt forms are used to improve handling (e.g., HCl salt for diamines), this will be declared on the Spec Sheet. In their absence, assume the free base.

Recommendation: Use the CoA to confirm assay, residual solvents, water content (Karl Fischer), and any trace impurities for your regulatory or process needs.

Reaction and Applications

As a multifunctional building block, 3-ethynylpyridine-2,6-diamine offers three orthogonal handles: a terminal alkyne, two primary amines, and a ring nitrogen.

• Terminal alkyne chemistry:

  • CuAAC “click” to 1,2,3-triazoles with organic azides (Cu(I) catalysts; amines/pyridine may chelate Cu—use excess ligand or protect amines if needed).
  • Hydrofunctionalizations: Hydrosilylation, hydroboration (to vinyl boronates), haloboration, and electrophilic additions to give halo- or haloalkenyl derivatives (literature precedents for terminal alkynes).
  • Oxidations and couplings: Glaser–Hay homocoupling to diynes (Cu, O2); Sonogashira-type C(sp)–C(sp2) couplings post-deprotonation to form internal alkynes.

• Amine-site transformations:

  • Selective acylation/sulfonylation/carbamoylation to tune electronics and block coordination.
  • Reductive amination and urea/thiourea formation for library synthesis.
  • Diazotization is not applicable to –NH2 on a pyridine ring; instead, use Sandmeyer-type strategies on anilines of benzenes. For pyridines, N-oxidation (to N-oxide) or directed lithiation may be leveraged.

• Ring nitrogen utility:

  • Acts as a ligand/anchoring site (e.g., for metal templated assembly) or site for N-oxide formation to direct ortho-functionalization (Chichibabin-type amination on pyridines is a classical context; adapt conditions carefully with existing –NH2 groups).

Applications:

• Fragment/linker for heteroaryl triazoles, peptidomimetics, and chelating scaffolds.
• Precursor to conjugated materials (diynes, enynes) while modulating basicity via amide protection.

Reaction Conditions

General literature guidance (not product-specific specifications):

• CuAAC (alkyne + azide → 1,2,3-triazole):

  • Catalyst: CuSO4·5H2O (1–5 mol%) + sodium ascorbate (reducing agent) or pre-formed Cu(I) complexes; TBTA or THPTA ligands mitigate amine/pyridine chelation.
  • Solvent: tBuOH/H2O (1:1), EtOH/H2O, or DMSO/H2O; 20–60 °C; 0.5–12 h, typically high conversions.

• Sonogashira-type coupling (from terminal alkyne to internal alkyne):

  • Catalyst: Pd(PPh3)2Cl2 (1–3 mol%); CuI (0–10 mol%) optional; base: Et3N, iPr2NEt, or K2CO3.
  • Solvent: DMF, 2-MeTHF, dioxane, or toluene/Et3N; 25–80 °C, 2–16 h. Copper-free variants reduce Glaser homocoupling.

• Hydroboration of terminal alkyne:

  • Reagents: Catecholborane or pinacolborane; catalysts: Rh, Ir, or Cu (NHC) systems; 0–50 °C; subsequent protodeboronation/Suzuki feasible.

• Amide formation on –NH2 groups:

  • Coupling reagents: HATU, HBTU, EDCI/HOBt (or OxymaPure); base: DIPEA.
  • Solvent: DMF, NMP, DCM/DMF mixtures; 0–25 °C initial, then to rt; 1–6 h. Protect one –NH2 for selectivity when needed.

• Protection strategies:

  • Boc protection: Boc2O, DMAP catalytic, base (Et3N), DCM or THF, 0–25 °C.
  • Cbz: Cbz–Cl, aqueous base biphasic or DMF with base.

Notes:

• The two –NH2 groups and pyridine N coordinate metals; add ancillary ligands (e.g., SPhos, XPhos, TBTA) to maintain catalyst activity.
• Exclude oxygen and copper if avoiding Glaser homocoupling; use degassed solvents and copper-free Pd catalysis.

Safety and Handling

• Item-specific GHS information: Not specified for this item; refer to SDS.
• Signal word / H-statements / pictograms: Not specified for this item; refer to SDS.

General safety considerations for heteroaromatic diamines and terminal alkynes (literature-based; not product-specific):

• Hazards: Aromatic diamines can cause skin/eye irritation and may be harmful if swallowed or inhaled; some may cause sensitization. Terminal alkynes can be flammable, particularly as vapors or solutions. Avoid dust formation and ignition sources.
• PPE: Use appropriate lab PPE—lab coat, nitrile gloves, safety goggles. Handle inside a fume hood to avoid inhalation of dust or vapors.
• Incompatibilities: Strong oxidizers (risk of exotherm/oxidation), acyl/alkylating agents (react with –NH2 groups), strong acids/bases (may cause salt formation or decomposition under forcing conditions). Copper salts catalyze Glaser homocoupling of terminal alkynes in air; exclude copper/oxygen if homocoupling is undesirable.
• First aid (overview; defer to SDS):
  • Inhalation: Move to fresh air; seek medical attention if symptoms persist.
  • Skin/eye contact: Rinse thoroughly with water for several minutes; remove contaminated clothing; obtain medical advice if irritation continues.
  • Ingestion: Rinse mouth; seek medical attention.
• Fire-fighting: Use CO2, dry chemical, or foam. Combustion may produce NOx and CO.
• SDS: Always consult the Safety Data Sheet for authoritative, product-specific guidance.

Solvent Selection

This compound is a polar, basic heteroaromatic with two –NH2 groups and a terminal alkyne.

• Polarity/miscibility (literature-based expectations):

  • Readily soluble: DMSO, DMF, NMP, MeOH, EtOH.
  • Moderately soluble: Acetonitrile, acetone, ethyl acetate (variable).
  • Poorly soluble: Aliphatic hydrocarbons (hexanes, heptane); toluene often limited unless warmed or with base.
  • Aqueous: Solubility increases upon protonation (e.g., HCl, H2SO4), forming water-soluble salts.

• Choosing solvents by application:

  • Cross-coupling on the alkyne (CuAAC, Sonogashira-type couplings of terminal alkynes): DMF, DMSO, dioxane, or alcohol/water mixtures; add base (e.g., DIPEA, Et3N) and consider copper scavengers post-reaction due to chelating amines.
  • Amide coupling on –NH2: Polar aprotics (DMF, NMP) or green alternatives (Me-THF, 2-MeTHF with co-solvent) to dissolve both coupling partners.
  • Salt-handling/purification: Use aqueous acid/base partitioning to switch between free base (organic-soluble) and protonated salt (water-soluble) forms.

• Comparison (typical):

  • DMSO/DMF: Maximum solubilization, but challenging removal.
  • Alcohols: Easier workup, but may participate in H-bonding and affect coupling reagents.
  • MeCN: Cleaner evaporation; verify solubility.

Always confirm solubility experimentally at your working concentration.

Storage and Reconstitution

• Storage conditions (from Product Data): Room temperature.
• Shipped in: Not specified for this item; refer to CoA/Spec Sheet.
• Appearance: Not specified for this item; refer to CoA/Spec Sheet.

Best practices (general):

• Keep container tightly closed in a dry, well-ventilated place. Protect from prolonged exposure to air and moisture to prevent gradual oxidation or adventitious salt formation.
• If forming salts (e.g., HCl) for handling, store accordingly in sealed containers with desiccant.
• For solution stocks: Prepare concentrated solutions in dry DMSO or DMF under inert gas; store aliquots at 2–8 °C for short term or −20 °C for longer term to limit degradation. Avoid repeated freeze–thaw cycles.
• Label solutions with solvent, concentration, date, and any stabilizers used.

Always refer to the product’s CoA/Spec Sheet and SDS for definitive storage and handling guidance.

Structure and Identity

A heteroaromatic diamine bearing a terminal alkyne on a pyridine ring. The parent ring is pyridine; amino groups are at the 2- and 6-positions, and an ethynyl (–C≡CH) substituent is at the 3-position.

• Item-specific identifiers (from Product Data):

  • SKU: E963659
  • Product Name: 3-Ethynylpyridine-2,6-diamine
  • CAS: 936342-42-6
  • InChIKey: Not specified for this item; refer to CoA/Spec Sheet.
  • SMILES: Not specified for this item; refer to CoA/Spec Sheet.

• Computed/literature (general, not item-specific specifications):

  • Typical molecular formula (based on the named structure): C7H7N3 (literature/computed)
  • Approx. molecular weight: ~133.15 g/mol (literature/computed)
  • Functional groups: pyridine nitrogen (sp2), two primary anilino-type amines (–NH2) at C2 and C6, terminal alkyne (–C≡CH) at C3.
  • Structural description (2D): A six-membered aromatic ring containing one ring nitrogen (position 1). Adjacent ortho positions (2 and 6) each bear –NH2 substituents. The meta position (3) carries a linear ethynyl substituent terminating in a hydrogen.

• Stereochemistry: None (achiral, no stereogenic centers).

Synthetic Utility

Multiple orthogonal reactive sites enable convergent synthesis and late-stage diversification:

• Alkyne handle:

  • CuAAC to 1,4-disubstituted triazoles (Cu(I)/ligand, aqueous or mixed media).
  • Sonogashira-type couplings from the terminal alkyne via deprotonation/activation to form C(sp)–C(sp2) bonds (or Glaser–Hay to diynes when desired).
  • Hydroboration to vinyl boronates, enabling subsequent Suzuki–Miyaura coupling.
  • Electrophilic additions (I2, NBS with catalysts) to access haloalkenes.

• Diamine handles (2,6-positions):

  • Selective protection strategies: Boc, Cbz, Fmoc to control reactivity and metal coordination.
  • Sequential acylation/sulfonylation to tune electronics and solubility; intramolecular cyclizations to benzimidazole-like or dihydropyrimidinone analogs are accessible with appropriate partners (literature on pyridine diamine condensations).

• Ring nitrogen:

  • N-oxide formation as a directing group for ortho-functionalization, followed by deoxygenation (Me3SiCl/PCl3 or PCl3-based protocols, literature).
  • Metal coordination for catalyst/ligand discovery.

Strategic value: The combination of a click-ready alkyne and two orthogonal amino groups supports parallel library synthesis and rapid vector exploration from a compact core.

Target Specificity

Not applicable. This product is a small-molecule building block, not a biological macromolecule or affinity reagent. No antigen/epitope or species reactivity applies.