7-Ethynyl-1H-indole - ≥95% , CAS No.1057670-22-0

CAS: 1057670-22-0 Cat. No.: E993244 Formula: C₁₀H₇N Peso molecolare: 141.170

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=CC=CC2=C1NC=C2
• IUPAC Name: 7-ethynyl-1H-indole
• InChIKey: ISZUMLLSBKWXNH-UHFFFAOYSA-N
• INCHI: 1S/C10H7N/c1-2-8-4-3-5-9-6-7-11-10(8)9/h1,3-7,11H
• Peso molecolare: 141.170

Taxonomic Classification

Taxonomy Tree

• Kingdom Organic compounds
  • Superclass Organoheterocyclic compounds
    • Classe Indoles and derivatives
      • Subclass Indoles

• Kingdom: Organic compounds
• Superclass: Organoheterocyclic compounds
• Classe: Indoles and derivatives
• Subclass: Indoles
• Intermediate Tree Nodes: Not available
• Direct Parent: Indoles
• Alternative Parents: Benzenoids Pyrroles Heteroaromatic compounds Azacyclic compounds Acetylides Organopnictogen compounds Organonitrogen compounds Hydrocarbon derivatives
• Molecular Framework: Aromatic heteropolycyclic compounds
• Substituents: Indole - Benzenoid - Heteroaromatic compound - Pyrrole - Acetylide - Azacycle - Organic nitrogen compound - Organopnictogen compound - Hydrocarbon derivative - Organonitrogen compound - Aromatic heteropolycyclic compound
• Descrizione: This compound belongs to the class of organic compounds known as indoles. These are compounds containing an indole moiety, which consists of pyrrole ring fused to benzene to form 2,3-benzopyrrole.
• 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: 141.170 g/mol
• XLogP3: 2.400
• Hydrogen Bond Donor Count: 1
• Hydrogen Bond Acceptor Count: 0
• Rotatable Bond Count: 1
• Exact Mass: 141.058 Da
• Monoisotopic Mass: 141.058 Da
• Topological Polar Surface Area: 15.800 Ų
• Heavy Atom Count: 11
• Formal Charge: 0
• Complexity: 188.000
• 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 validated bioassay or analytical application protocols are provided for this item. Typical laboratory uses are synthetic and will follow reaction‑specific procedures (e.g., CuAAC, Sonogashira, Glaser couplings) as outlined under Reaction Conditions.

General handling for stock solutions (common practice, not a specification)

• Prepare concentrated stocks in dry DMSO or DMF (e.g., 10–50 mM). Filter if necessary. Store aliquots to avoid repeated freeze–thaw.
• For bioconjugation, combine with azides under CuAAC conditions using appropriate copper sources, reductants, and ligands; remove copper post‑reaction for biological compatibility.

Refer to primary literature or internal SOPs for experiment‑specific details.

Biological Roles

This product is a synthetic small‑molecule building block and is supplied for research use only. It is not intended for biological administration. The notes below describe general roles of the indole motif in biochemistry (literature) and do not pertain to any clinical use.

• Indole core: Found in the amino acid tryptophan and numerous natural products; engages in π–π stacking, cation–π interactions, and hydrogen bonding via the indolic N–H.
• Terminal alkyne handle: Enables installation of bio‑orthogonal linkers via CuAAC to prepare triazole‑linked probes, affinity tags, or fluorophore conjugates on indole‑containing frameworks.
• Photophysics: Indole chromophores exhibit characteristic UV fluorescence that can be modulated by conjugation through an ethynyl substituent; useful in designing reporter systems (literature concept).
• Enabling chemistry: The indole’s C3 reactivity allows late‑stage diversification for SAR studies, while the alkyne serves as an orthogonal coupling point—valuable for fragment‑based design and probe assembly.

Note: Any biological testing must be conducted according to institutional safety protocols. No pharmacological, toxicological, or clinical properties are claimed or implied for this catalog item.

Buffer Applications

Not typically applicable. 7‑Ethynyl‑1H‑indole is a hydrophobic organic building block and does not function as a buffering agent. For aqueous work, it is commonly dissolved first in a water‑miscible organic co‑solvent (e.g., DMSO) and then diluted into buffer, ensuring final co‑solvent levels are compatible with the assay.

For buffer selection relevant to bioconjugation (CuAAC), choose systems that maintain copper speciation and reductant stability (e.g., phosphate or tris buffers at neutral pH with sodium ascorbate), but the compound itself does not set buffer pH.

Green Alternatives

Opportunities to improve the sustainability profile when working with 7‑ethynyl‑1H‑indole focus on solvent and catalyst choices rather than changing the substrate.

Greener solvent choices (literature)

• Replace DMF/DMSO with bio‑derived or lower‑toxicity media where possible: 2‑MeTHF, CPME, toluene, or EtOH/H2O mixtures for couplings; PEG‑400 or glycerol as unconventional media.
• Purification: Favor heptane/EtOAc over hexane/CH2Cl2 systems; employ reverse‑phase chromatography with water/MeCN to reduce chlorinated waste.

Catalyst/condition optimizations

• Sonogashira: Use Pd at ppm levels with robust ligands; explore Cu‑free protocols to minimize copper waste and Glaser byproducts. Aqueous micellar catalysis (e.g., TPGS‑750‑M) can enable room‑temperature couplings in water.
• CuAAC: Perform in water/tert‑BuOH or PEG‑400 with sodium ascorbate to generate Cu(I) in situ, minimizing organic solvent and harsh reagents.

Comparison snapshot (general)

• DMF vs 2‑MeTHF: 2‑MeTHF is bio‑based and easier to remove; DMF offers higher polarity/solvency but is a reproductive toxin and problematic waste stream.
• CH2Cl2 vs toluene: Toluene reduces chlorinated waste and often supports high‑temperature couplings; DCM offers low‑temperature control but has higher environmental concerns.

Note: No green specifications are set for this item; the suggestions are literature best practices to reduce E‑factor and hazard.

Pharmaceutical Uses

This item is a research chemical building block and is not an excipient or an active pharmaceutical ingredient in this catalog context.

• Pharmacopeia status: Not specified for this item; no compendial monograph is indicated.
• Typical formulation roles: None. As a synthetic intermediate, it may be used to prepare investigational compounds or materials during discovery, but it is not itself formulated for administration.
• Process considerations (general): If used in route scouting, evaluate purge of metal catalysts from downstream steps and establish impurity fate maps for indole/alkyne‑derived impurities.

No medical or clinical claims are made. For any regulated application, verify identity, purity, and residuals against internal specifications and applicable guidelines.

Physical Properties

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.

Literature/general values for the compound class (indole alkynes; for planning only)

• Molecular formula (literature): C10H7N
• Molecular weight (literature): ~141.17 g/mol
• State: Typically a crystalline solid or low‑melting solid for many aryl‑ethynyl indoles; exact MP/BP not specified for this item.
• Solubility (qualitative, literature): Low in water; good to excellent in polar aprotic organic solvents (DMSO, DMF, NMP) and chlorinated solvents (CH2Cl2, CHCl3); moderate in ethyl acetate and aromatics (toluene). Actual solubility can vary by batch/form.
• UV–Vis: Indole chromophore typically absorbs in the near‑UV (e.g., 210–290 nm); exact λmax not specified for this item.
• pKa: Indole N–H is weakly acidic (pKa ~16–17 in DMSO, literature). Terminal alkyne C–H pKa ~25 (DMSO, literature). Actual values depend on medium.
• LogP: Indole alkynes are generally moderately lipophilic; specific logP not specified for this item.

Notes

• Do not treat literature values as product specifications. For release specifications (e.g., melting range, residual solvents, water), consult the CoA/Spec Sheet.

Quality and Grades

Item-specific grade/purity

• Grade/Purity: Not specified for this item; refer to CoA/Spec Sheet for assay, residual solvents, and analytical release tests.

Guidance on typical quality attributes for heteroaromatic building blocks

• Identity: Commonly confirmed by 1H/13C NMR, HRMS, and sometimes IR (alkyne C≡C stretch) and HPLC/GC purity. Indole N–H and alkyne proton provide diagnostic NMR signals.
• Purity reporting: May be reported as area% by HPLC/GC or weight% by qNMR. For photonics/materials work, confirm metal content if used post‑coupling.
• Stabilizers: None are typically added to indole alkynes; this item lists none. If a stabilizer is present on your CoA, consider its impact on downstream chemistry (e.g., BHT in radical reactions).
• UV cutoffs/LC compatibility: If planning UV‑based detection, verify background absorbance in your specific mobile phase (not specified for this item).

What the grades mean (general)

• “Research grade”/catalog grade: Suitable for general synthesis and screening.
• “HPLC grade solvents” or “spectrophotometric grade” do not apply here; for reaction solvents choose grades appropriate to your application.

Recommendation

• For sensitive applications (photophysics, trace catalysis), request CoA with impurity profile, water content, and, if relevant, residual metal analysis. Always verify specifications lot‑by‑lot.

Reaction and Applications

7‑Ethynyl‑1H‑indole is a dual‑functional building block combining an electrophile‑resistant indole core with a nucleophilic/acidic terminal alkyne. This enables diverse bond‑forming strategies:

• Click chemistry (CuAAC, literature): The terminal alkyne undergoes Cu(I)‑catalyzed azide–alkyne cycloaddition to give 1,4‑disubstituted triazoles, enabling bioconjugation, linker installation, and library synthesis on an indole scaffold.
• Cross‑coupling extensions: Via Sonogashira coupling of the terminal alkyne with aryl/vinyl halides (Pd/Cu or Cu‑free systems), accessing di‑ or tri‑aryl ethynyl architectures and push–pull chromophores.
• Oxidative homocoupling: Glaser–Hay coupling to symmetrical diynes; Eglinton (CuII) as an alternative when amines are undesirable.
• N‑functionalization: The indolic N–H can be protected (e.g., Boc, SEM) or directly alkylated/acylated under mild base. N‑protection often improves regioselectivity in C‑H functionalization at C2/C3.
• Electrophilic substitution at C3 (literature hallmark of indoles): Formylation (Vilsmeier), acylation, or Friedel–Crafts additions can be performed orthogonal to the alkyne, enabling multiplexed diversification.
• Metalation chemistry: Deprotonation of the alkyne (e.g., n‑BuLi, NaNH2) forms acetylides for nucleophilic additions to carbonyls or transmetalation into Cu/Ag for further coupling.

Practical tips

• Protect the indole N–H if using strong base or if competitive N‑metalation reduces coupling efficiency.
• Terminal alkynes can bind Pd/Cu; adjust ligand/base to suppress Glaser side reactions during Sonogashira.
• Degas solvents for Pd‑catalyzed transformations; oxygen promotes oxidative dimerization of alkynes.

Note: The above are literature‑based application concepts; adapt conditions to your system.

Reaction Conditions

General literature conditions for common transformations of 7‑ethynyl‑1H‑indole (guidance only; optimize per system):

• CuAAC (azide–alkyne cycloaddition): CuSO4·5H2O (1–10 mol%) + sodium ascorbate (5–20 mol%) in t‑BuOH/H2O (1:1) or DMF/H2O at rt to 50 °C, 1–16 h. Ligands (TBTA/THPTA) improve kinetics in water. Typically affords triazoles in high yields.
• Sonogashira coupling (extend alkyne): Pd(PPh3)2Cl2 (0.5–2 mol%) + CuI (1–5 mol%), base iPr2NH, Et3N, or K2CO3, solvent THF, DMF, or toluene, 25–80 °C, 2–12 h. For Cu‑free: Pd(P(tBu)3)2 or XPhos‑type systems; add molecular sieves to suppress Glaser coupling.
• Glaser–Hay dimerization: CuCl (5–10 mol%), TMEDA (10–20 mol%), O2 or air, toluene or pyridine, 25–60 °C, 2–24 h to form 1,3‑diynes. Control oxygen carefully to limit over‑oxidation.
• Alkyne deprotonation/acetylide formation: n‑BuLi (1.0–1.1 equiv) in THF or Et2O at −78 to 0 °C, then trap with electrophiles (R–X, carbonyls). N‑protection of indole recommended to avoid competing N‑lithiation.
• Indole C3 formylation (Vilsmeier): POCl3/DMF (excess) at 0–25 °C then warm to 60–80 °C, quench to deliver 3‑formyl derivatives; protect alkyne if sensitive substrates are present.

Workup and purification

• Chelate or scavenge residual Cu/Pd (e.g., EDTA washes, metal scavenger resins). Silica gel can catalyze alkyne hydration—minimize residence time if sensitive.

Note: No specific reaction performance data are provided for this item; conditions are literature norms.

Safety and Handling

Authoritative safety data are provided in the product SDS. The following points are general guidance for indole alkynes and do not substitute for the SDS.

Item-specific hazard information

• GHS classification, pictograms, signal word, and H‑statements: Not specified for this item; refer to SDS.

General precautions for 7‑ethynyl‑1H‑indole and related aryl‑alkynes

• Likely hazards: Many indole derivatives and terminal alkynes can cause irritation to skin/eyes/respiratory tract. Avoid inhalation of dust and contact with skin/eyes.
• PPE: Wear lab coat, safety glasses, and appropriate disposable gloves (e.g., nitrile). Handle powders in a fume hood.
• Handling: Avoid strong bases unless intentional (deprotonates alkyne). Minimize exposure to strong oxidants. Prevent static/dust generation.
• Incompatibilities: Strong oxidizers; strong bases will form metal acetylides with Cu/Ag salts. Avoid azides plus heavy‑metal catalysts unless performing controlled click chemistry.
• First aid (overview): If inhaled—fresh air; if on skin—wash with soap and water; if in eyes—rinse cautiously with water for several minutes; if ingested—rinse mouth. Seek medical attention as needed.
• Fire: Many aryl heterocycles are combustible. Use CO2, dry chemical, or foam. Combustion may release NOx and CO; self‑contained breathing apparatus recommended for large fires.
• Waste: Collect organic waste according to local regulations. Residual metal catalysts from couplings should be disposed of as hazardous waste.

Storage

• Store tightly closed at room temperature as provided in Product Data. Protect from light and moisture for best stability. Refer to SDS for detailed storage classes.

Solvent Selection

Solubility and polarity profile (general guidance for indole alkynes)

• Water: Practically insoluble.
• Polar aprotic: Typically highly soluble in DMSO, DMF, NMP, and DMAc—preferred for stock solutions and polar couplings.
• Moderately polar organics: Good solubility in CH2Cl2/CHCl3 and EtOAc; variable in MeCN and acetone.
• Nonpolar/aromatic: Often soluble in toluene and THF; solubility may improve with mild heating.

Selection tips by application

• Stock solutions for biology/assays: DMSO is commonly used; filter sterilize if needed. Prepare concentrated stocks (e.g., 10–50 mM) and dilute into assay buffers with vigorous mixing to avoid precipitation.
• Cross-coupling/click chemistry: Choose solvent based on catalyst system—DMF/DMAc, DMSO, dioxane, toluene, or mixed iPr2NH/THF for Sonogashira; t‑BuOH/H2O or DMF/H2O for CuAAC.
• Purification: Normal‑phase flash with hexanes/EtOAc or DCM/MeOH systems works for many indoles. Reverse‑phase prep HPLC may be preferable for closely related analogs.

Comparison (general)

• DMSO vs DMF: DMSO offers higher solvency and lower volatility; DMF is easier to remove. Both can coordinate metals—adjust catalyst loadings accordingly.
• CH2Cl2 vs toluene: DCM enables lower‑temperature control; toluene suits higher‑temperature couplings and is more environmentally favorable than chlorinated solvents.

Note: Exact solubility and solvent compatibility are not specified for this item; verify experimentally.

Storage and Reconstitution

Item-specific storage

• Storage conditions: Room temperature (per Product Data). Keep container tightly closed.

Best practices (general guidance for indole alkynes)

• Protect from light and moisture to minimize discoloration or slow oxidation/polymerization of the alkyne.
• If prolonged storage is anticipated, consider inert‑atmosphere storage (argon) and inclusion of a desiccant.
• Avoid contact with copper/air during storage to limit Glaser‑type dimerization.

Reconstitution/solution preparation

• Solvents: DMSO, DMF, CH2Cl2, or toluene typically dissolve indole alkynes well. Actual solubility for this item is not specified; verify experimentally.
• Stock preparation: Make fresh, anhydrous solutions for moisture‑sensitive reactions. For assay use, prepare DMSO stocks and dilute into buffer with vigorous mixing to avoid precipitation.
• Freeze–thaw: If storing solutions, aliquot to minimize freeze–thaw cycles; inspect for precipitate or color changes before use.

For definitive storage limits, retest intervals, and solution stability, consult the CoA/SDS. Research use only.

Structure and Identity

Overview: 7‑Ethynyl‑1H‑indole is an indole heteroaromatic bearing a terminal alkyne at the 7‑position of the benzene ring and a free indolic N–H (1H tautomer). It is a versatile building block for conjugated materials and late‑stage diversification via alkyne chemistry.

Item-specific (from Product Data)

• Product name: 7‑Ethynyl‑1H‑indole
• CAS: 1057670-22-0
• CID: 53434688
• InChIKey: 149789 (as provided)
• Storage: Room temperature

Literature/Computed identifiers and features (for general reference; not item specifications)

• Typical molecular formula (literature): C10H7N
• Typical molecular weight (literature): ~141.17 g/mol
• Core scaffold: Indole (benzannulated pyrrole)
• Functional groups: Terminal alkyne (–C≡CH), secondary amine (indolic N–H), polyaromatic system
• Structural description (2D): A bicyclic indole ring (five‑membered pyrrolic ring fused to a benzene ring). The terminal alkyne substituent is attached at the benzene ring’s 7‑position; the pyrrolic nitrogen is unsubstituted (1H).

Notes

• SMILES and full standardized InChI were not specified for this item; refer to CoA/Spec Sheet.
• Always confirm exact regiochemistry and identifiers on the CoA prior to use in regulated workflows.

Synthetic Utility

Functional group leverage

• Terminal alkyne (–C≡CH): Serves as a linchpin for CuAAC click reactions, Sonogashira extensions, hydrofunctionalizations (hydroboration‑oxidation to aldehydes/ketones after homologation), and metal acetylide additions to electrophiles.
• Indolic N–H: Enables N‑protection (Boc, Cbz, SEM) to direct reactivity; N‑alkylation/acylation installs solubilizing groups or handles for further coupling.
• Indole ring: Predisposed to electrophilic substitution at C3; C–H activation at C2/C7 under Pd/Ir/Rh catalysis provides complementary entry points.

Retrosynthetic value

• The ethynyl group provides a convergent handle to append the indole onto azide‑bearing fragments via triazoles, or to extend π‑systems for optoelectronic materials.
• Orthogonality: Alkyne chemistry can proceed under conditions that spare the indole core; conversely, indole‑directed transformations can proceed with the alkyne masked (e.g., TMS‑protection) if necessary.

Named transformations (literature)

• CuAAC (Huisgen, Cu‑catalyzed), Sonogashira, Glaser–Hay/Eglinton, Vilsmeier formylation at C3, Fischer indole chemistry for analog preparation, and Boger‑type cycloadditions on activated indoles.

Practical guidance

• Consider TMS protection of the terminal alkyne to suppress oxidative dimerization during storage or harsh steps; deprotect with K2CO3/MeOH.
• When pursuing Pd‑catalyzed routes, N‑protection can improve yields by reducing catalyst poisoning by the indolic N–H.

Target Specificity

Not applicable. This catalog item is a small‑molecule building block, not a biological macromolecule or antibody. No target, epitope, clone, or species reactivity information applies.