4,4'-Di-tert-butyl-2,2'-bipyridyl (HPMC encapsulated)

• 2-Bromopyridine [B0650]
• Indole [I0021]
• Cesium Carbonate [C2160]
• Cupper Iodide (HPMC encapsulated) [R0314]
• 4,4'-Di-tert-butyl-2,2'-bipyridyl (= dtbpy) (HPMC encapsulated) [R0320]
• DMSO

Copper(I) iodide (HPMC encapsulated) (one capsule) and dtbpy (HPMC encapsulated) (one capsule) were added to a solution of indole (93.7 mg, 800 µmol), 2-bromopyridine (190 mg, 1.20 mmol, 1.5 eq.) and cesium carbonate (521 mg, 1.60 mmol, 2.0 eq.) in DMSO (2.5 mL) at room temperature and the reaction mixture was stirred at 120 °C for 2 hours. After cooling to room temperature the solution was diluted with ethyl acetate (10 mL) and sat. Na₂SO₄ aq. (10 mL), and filtered through Celite pad and washed by ethyl acetate (50mL). Water (10 mL) was added to the filtrate and extracted with ethyl acetate (10 mL x 2). The organic layer was dried over sodium sulfate and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography (ethyl acetate:hexane = 1:10 - 1:5) to afford N-(2-pyridyl)indole (120 mg, 70% yield) as a pale-yellow oil.

The reaction mixture was monitored by GC.
The material of the capsule is water-soluble HPMC (hydroxypropyl methylcellulose).
The shape of the capsule is like the image below and copper(I) iodide (ca. 800 μmol) and dtbpy (ca. 200 μmol) are encapsulated in each capsule, respectively.

The capsule disintegrates as shown in the image below when stirred in the solvent for about 15 minutes, releasing its content.

N-(2-Pyridyl)-indole

¹H NMR (400 MHz, CDCl₃); δ 8.21 (d, J = 8.0 Hz, 1H), 7.85-7.81 (m, 1H), 7.37 (d, J = 4.0 Hz, 1H), 7.67 (d, J = 8.0 Hz, 1H), 7.51 (d, J = 8.0 Hz, 1H), 7.30(t, J = 8.0 Hz, 1H), 7.23-7.16 (m, 2H).

• Reagent and Catalyst Capsules: A Chemical Delivery System for Reaction Screening and Parallel Synthesis
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• HPMC: A Biomass-Based Semisynthetic Sustainable Additive Enabling Clean and Fast Chemistry in Water
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