Triethylamine → 5-Bromo-3-(2-triethylsilylethynyl)pyrazin-2-amine

Participants

Reaction Steps

Triethyl(ethynyl)silane (6.102 g, 7.793 mL, 43.49 mmol) followed by triethylamine (5.201 g, 7.164 mL, 51.40 mmol) was added to a thoroughly degassed suspension of 3,5-dibromopyrazin-2-amine (10 g, 39.54 mmol), copper(I) iodide (753.0 mg, 3.954 mmol) and Pd(PPh3)2Cl2 (2.775 g, 3.954 mmol) in tetrahydrofuran (200.0 mL) and the resulting solution stirred at ambient temperature over 18 hours. (On addition reaction mixture changes colour rapidly from yellow to orange to red to dark red and brown and then orange). Reaction mixture is cooled to ambient temperature and then diluted with EtOAc and 10% solution of NH4OH (100 mL) added and the layers separated. EtOAc layer washed once more with 10% NH4OH. Aqueous layer extracted further with EtOAc (×3) and combined organics dried over (MgSO4), filtered and concentrated in vacuo to a brown oil. Purified on Companion using a 330 g pre-packed silica column loading with DCM and eluting with 0-100% Petrol/DCM. Relevant fractions combined and concentrated in vacuo to give a brown oil (11.24 g, 91%). 1H NMR (400.0 MHz, DMSO) δ 0.67-0.74 (m, 6H), 0.99-1.03 (m, 9H), 6.72 (s, 2H) and 8.14 (s, 1H) ppm; MS (ES+) 314.06.

Provenance & Evidence