Trimethylsilylacetylene → 2-Bromo-5-trimethylsilanylethynyl-pyrazine

Participants

Reaction Steps

A mixture of 2-bromo-5-iodo-pyrazine (1.14 g, 4.0 mmol) and copper (I) iodide (80 mg, 0.42 mmol) in DMF/Et3N (2:1, 24 ml) was deoxygenated by evacuate/refill with nitrogen (×3). Ethynyl-trimethyl-silane (680 μl, 4.8 mmol) followed by Pd(PPh3)4 (230 mg, 0.2 mmol) were added and the mixture was deoxygenated again (×1). The reaction was stirred at RT for 16 hours, then partitioned between Et2O/H2O. The organic layer was washed with water (×1), brine (×1), then dried (MgSO4), filtered and evaporated. The residue was purified by chromatography on silica (2∝34% Et2O/Petrol) to give the title compound (850 mg, waxy solid) as ˜3:1 mixture of mono coupled product to bis coupled. 1H NMR (400 MHz, CDCl3): 8.63 (1H, d), 8.43 (1H, d), 0.25 (9H, s), [Bis coupled product: 8.60 (s), 0.25 (s)] This material was used without further purification.

Provenance & Evidence