Safety and Pre-Use Precautions

Before handling 2-(5-Bromopyridin-3-yl)-5-propyl-1,3,4-oxadiazole (B179918), review the current Safety Data Sheet (SDS) supplied by Aladdin Scientific. As a brominated heterocyclic compound, standard precautions for organic research reagents apply:

• Wear appropriate personal protective equipment (PPE): nitrile gloves, lab coat, and safety goggles.
• Handle in a well-ventilated fume hood to minimise inhalation exposure to fine particulates or vapours.
• Avoid contact with skin, eyes, and mucous membranes.
• In the event of skin contact, wash thoroughly with soap and water; for eye contact, irrigate immediately with copious water and seek medical attention.
• Organic bromides may be irritants; treat all exposures seriously and consult the SDS for first-aid measures.

Note: Specific toxicological data for this compound have not been confirmed in the source material; consult the product SDS and exercise standard laboratory caution.

Dissolution and Solution Preparation

2-(5-Bromopyridin-3-yl)-5-propyl-1,3,4-oxadiazole contains both a polar oxadiazole ring and a lipophilic propyl chain, which together confer moderate polarity. The following guidance is based on the general solubility behaviour of analogous oxadiazole-pyridine compounds:

1. Solvent selection: Dimethyl sulfoxide (DMSO) and N,N-dimethylformamide (DMF) are typically suitable primary solvents for initial stock solution preparation. Dichloromethane (DCM) and ethyl acetate may be used for synthetic applications.
2. Stock solution preparation: Weigh the required mass accurately using an analytical balance. Dissolve in DMSO to prepare a concentrated stock (e.g. 10–100 mM), vortexing or sonicating gently until fully dissolved.
3. Dilution: For biological assays, dilute the DMSO stock into aqueous buffer immediately before use; keep the final DMSO concentration ≤0.1% v/v unless validated otherwise for the assay system.
4. Clarity check: Inspect the solution visually for cloudiness or precipitation before use; if precipitation is observed, warm gently or add a small volume of co-solvent.

Review flag: Specific solubility values (mg/mL) for B179918 were not provided in the source material and should be verified experimentally or confirmed with Aladdin Scientific technical support.

Synthetic Applications and Cross-Coupling Protocol

The aryl bromide functionality on the pyridine ring of 2-(5-Bromopyridin-3-yl)-5-propyl-1,3,4-oxadiazole makes it a versatile electrophilic partner in palladium- and nickel-catalysed cross-coupling reactions. Representative applications include:

• Suzuki–Miyaura coupling: React with aryl- or heteroarylboronic acids in the presence of a Pd catalyst (e.g. Pd(PPh₃)₄ or Pd(dppf)Cl₂) and a base (K₂CO₃ or Cs₂CO₃) in a mixed aqueous/organic solvent (e.g. DMF/H₂O or dioxane/H₂O) at 80–100 °C.
• Buchwald–Hartwig amination: Couple with primary or secondary amines using Pd₂(dba)₃ with a bulky phosphine ligand (e.g. BINAP or XPhos) and a base such as Cs₂CO₃ in toluene or dioxane at elevated temperature.
• Negishi coupling: React with organozinc reagents under Pd catalysis for C–C bond formation.

General Suzuki coupling procedure (representative):

1. Charge a Schlenk flask with B179918 (1.0 equiv.), boronic acid (1.2 equiv.), Pd(PPh₃)₄ (2–5 mol%), and K₂CO₃ (2.0 equiv.).
2. Add degassed DMF/H₂O (4:1 v/v) under nitrogen.
3. Stir at 90 °C for 12–16 h.
4. Cool, dilute with ethyl acetate, wash with brine, dry over Na₂SO₄, filter, and concentrate.
5. Purify by column chromatography (silica gel) or recrystallisation.

Review flag: Specific reaction conditions, yields, and literature precedents for B179918 in cross-coupling have not been confirmed in the source material. Conditions above are general guidance for aryl bromide substrates bearing oxadiazole groups.

Storage, Stability, and Waste Disposal

Storage: Store 2-(5-Bromopyridin-3-yl)-5-propyl-1,3,4-oxadiazole in a tightly sealed container in a cool, dry, well-ventilated area away from direct light and ignition sources. After opening, consider re-sealing under inert gas (nitrogen or argon) to prevent moisture uptake and potential hydrolysis of the oxadiazole ring over time.

Stability: The 1,3,4-oxadiazole ring is generally stable under ambient conditions when kept dry. Prolonged exposure to strong acids, strong bases, or high humidity may cause degradation. Store away from oxidising agents and strong nucleophiles that could react with the aryl bromide.

Recommended storage temperature: Room temperature to 4 °C (consult the product label for the specific recommendation for B179918).

Waste disposal: Dispose of this compound and contaminated materials in accordance with local, national, and institutional regulations for organic chemical waste. Do not pour into drains or waterways. Use appropriate labelled waste containers.

Review flag: Specific stability data, shelf-life, and recommended storage temperature for B179918 were not confirmed in the source material and should be verified with Aladdin Scientific or from the product certificate of analysis.