2-Chloro-5-iodopyrazine

2-Chloro-5-iodopyrazine (CAS 1057216-55-3) is a strategically bifunctional halogenated pyrazine scaffold engineered for highly chemoselective cross-coupling reactions, pharmaceutical intermediate synthesis, and materials science development. This molecule integrates an electron-deficient pyrazine core—a six-membered aromatic diazine ring with nitrogen atoms at para positions (1,4)—with a chlorine substituent at the C2 position and an iodine atom at the C5 position. The dual halogen architecture with significantly differentiated reactivity (I >> Cl) enables precise sequential functionalization, allowing researchers to introduce distinct substituents at each position through controlled Pd-catalyzed cross-coupling. The iodine handle offers rapid oxidative addition kinetics, while the chlorine site remains inert under mild conditions, providing superior orthogonality compared to bromo/iodo analogs. The 2,5-substitution pattern creates a symmetric geometry across the ring center, making this intermediate particularly valuable for constructing asymmetric ligands, fused heterocycles (pyrazino-fused systems), kinase inhibitor cores, and conjugated materials where stepwise derivatization with high selectivity is critical. Manufactured with purity ≥98% under controlled conditions, it supports drug discovery programs requiring modular access to differentially halogenated electron-deficient heterocycles with enhanced control over reaction sequences.