Palladium-catalyzed cross-coupling of various phosphorus pronucleophiles with chloropyrazines: synthesis of novel Am(III)-selective extractants.

Palladium-catalyzed cross-coupling of (di)chloropyrazines with phosphorus pronucleophiles in the presence of a base gave the phosphorylated pyrazines in 81-95% yields. Based on this methodology a series of appropriately functionalized pyrazines was prepared as potential extractants of trivalent cations from highly acidic nuclear waste. A few hydrophilic derivatives exhibited a very good selectivity for Am(3+) over Eu(3+) with separation factors up to 40 at pH 1 at 0.01 mol L(-1) ligand concentration.